Notice! It is a violation of U.S. Federal law to remove, modify or disable emission control devices. Some states, like California, have laws above and beyond Federal regulations.
Fiero has very little in the way of emission control hardware. There is only the catalytic converter, EGR valve and a fuel vapor recovery canister. None of which require rocket science to fix. (In California nearly all parts of the engine are regulated. Make sure any aftermarket parts you install meet CARB requirements.) There’s also the PCV system. Almost forgot that one.

Catalytic Converter

The catalyst is used to burn off excess fuel and oil that escapes normal combustion. The catalyst usually fails in one of 2 ways. It either disintegrates or gets plugged up with soot. In extreme cases the guts can melt. (Usually if it disintegrates it blocks up the exit port.) The catalyst needs to be replaced when it fails. You can’t fix it.
You want to know which way it failed. If it fell apart then you can likely just replace it but if it’s blocked up with carbon or melted then try to find out why before you install a new one. If the motor is running rich, burning oil, or leaking coolant then these problems must be fixed before the new catalyst is installed otherwise you’ll wreck the new one in short order.
A quick way to test the catalyst is to measure backpressure at the O2 sensor port. According the June 2001 issue of Motor…
With the engine idling, the pressure will usually be below 1 psi on a good system.
Backpressure reading over 1.5 psi is cause for concern. Next, bring the rpm to 2000 and check the pressure again. A good system will usually show less than 2 psi. If the pressure is over 3 psi, the catalyst is most likely going south.
Of course most people don’t have the fancy commercial one of these lying around, but they can be made. You’ll want to use some metal or high temperature flexible tubing to keep the gauge away from the worst heat. You also want a gauge made for low pressure, something with a 5-10psi top end.
You can use an old O2 sensor or spark plug to fabricate the exhaust fitting.
If the catalyst croaks… Once the catalyst is off make sure it hasn’t blown its cookies down the exhaust pipe. With Fiero’s exhaust setup, you can probably suck the stuff back out of the muffler with a shop vac. (Empty the vacuum before starting so you can tell what came out of the exhaust.) If you don’t check for this you could fry the new catalyst. At the very least the exhaust will still be restricted and likely hurt performance.
Many people think the catalyst does nothing but rob performance. Once upon a time this may have been true but today’s high flow catalyst units present very little restriction of exhaust flow. In the vast majority of cases you gain nearly the same performance increase with a new catalyst as having a straight pipe.
·     A straight pipe may give a HP increase but can reduce low-end torque in many engines.
· A straight pipe on an engine with backpressure EGR may also cause odd problems. These engines must have some backpressure to operate properly.
It is illegal in some places to put used catalysts in the trash. Even when it isn’t illegal try to dispose of it at a muffler repair shop or some other place that will send them to be recycled. (They recycle both the metal and the catalyst material.)

EGR

Note! An altered or defective exhaust system can screw up operation of the EGR valve on the L4. How much depends on the specific alteration or defect.
The EGR, Exhaust Gas Recirculation, valve is used to limit emissions and to prevent engine knock. On V6 the valve is ECM controlled but on the L4 it is operated by a combination of engine vacuum and exhaust back pressure.
There’s not much to go wrong with the valve. It can jam or leak which is usually caused by carbon and rust in the valve base. The diaphragm that moves the valve can deteriorate and leak. That’s about it. (In one odd case, I had the return spring or something in the vacuum chamber broke.)
You have to watch that the valve is connected to the right vacuum source. That information is on the VECI, Vehicle Emission Control Information, label on the deck lid. Hooking it up wrong can make it open at the wrong time or not at all.
The main problems with this valve on the V6 are that the valve plumbing likes to crack and the ECM control solenoid likes to get trash in it. The cracks of course hurt engine performance, if the car even runs with these vacuum leaks.
The control solenoid can sometimes be cleaned but you have to watch what you clean it with. You want a plastic friendly solvent that leaves no residue or lubricant behind to collect more dirt.
If you suspect EGR valve problems, take it off and inspect it. The gasket for the L4 valve is only about $1.00. I imagine the V6 one is about the same. (FelPro gaskets…) Always install a new gasket if you remove the EGR. A small exhaust or vacuum leak can cause major hair pulling…
Carbon or corrosion on the valve can hang the valve open or shut. You may be able to clean carbon off with EFI system or Carburetor cleaner. Corrosion will usually mean valve replacement.
Shake the valve. Noise is bad… Nothing in it should rattle.
Push the diaphragm up. You may have to carefully use a tool of some type. (A stick of Plastic or Wood is probably safer than metal.) Does it move smoothly and return to the closed position by itself? If not the valve probably needs replacement.

When does EGR open?

That depends on the EGR in question. I can tell you when it should definitely NOT open. It should not be open at idle or at WOT. Otherwise… On the ECM controlled ones it will open whenever the ECM is programmed to open it.
On backpressure ones, like the Fiero stock 4 cyl, it will open at certain combinations of vacuum and exhaust pressure. Exactly when those conditions will be met is hard to say. It will vary based on the condition and configuration of your car and you driving habits.

Service Warning!

THIS APPLIES TO ALL VEHICLES FITTED WITH THE UNIVERSAL EGR VALVES.
Many replacement EGR valves are of the universal type and come with metering washers that are affixed to the valve prior to installation on the car.
These washers MUST be staked in place. Do not depend on the gasket to hold them. If the washer comes loose it will screw up the metering allowing more exhaust gas flow than it’s supposed to. The washer could even fall into the motor and cause major damage.
To stake them down place a punch or the corner of a chisel in the base of the EGR valve next to the washer seat. Hit the punch to dent the valve base and force metal toward the washer. Do this in at least 3 locations around the washer.
Record the number of the original valve to both the sticker included with the valve and a permanent location on the vehicle or in some other place you can find it again. The label often fades. You’ll need the number if you ever have to replace it again.
To select the correct washer you need the code stamped into the OE EGR shell…

Fuel Vapor Canister

The Fuel Vapor can is a little confusing for many people. It is simply a can of charcoal with a vacuum controlled air vent stuck on it. The emission control purpose of the canister is of course to prevent fuel vapor from leaving the gas tank but it also saves you money if it works right. Fuel that evaporates from your tank costs money and gives nothing in return. The canister catches this fuel and lets the car use it. It’s a small amount at any one time but over the life of a car it can really add up especially in hot climates. A canister that is working right will not hurt performance and will add ever so slightly to your MPG.
The Canister Purge uses two vacuum lines. The large one goes to manifold vacuum and carries the fuel vapor into the engine to be burned. The small one is the control line and goes to a port on the throttle body that opens upstream of the throttle butterfly. When the throttle opens beyond a certain range the purge control valve opens and allows manifold vacuum to draw the vapor from the can.
The only maintenance the canister needs is periodic checking of the vacuum lines and filter. There is a floss filter on the bottom to trap large dirt from entering the can and plugging it up. That filter needs to be kept clear of major trash and should be replaced once in awhile or when damaged. (The filter costs
about a dollar at Wal-Mart.)
There are only a couple things that can go wrong with the canister. It can be damaged by cracking the thing or by over filling the gas tank. “Topping off” the gas tank can force fuel up the vent line into the can and ruin it. While the fuel pump nozzle is supposed to shut off when the tank is full, they are often bad and can pressurize the fuel tank enough to force fuel up the vent. Certain types of “Vapor Recovery” nozzles are great for this.
The purge control valve can fail or its line can be connected to the engine wrong. Either can cause problems. The routing of these lines is also on the VECI label.
The fastest way to test for drivability problems caused by the vapor can is to disconnect and block both vacuum lines. If the problem stops, the vapor can is bad.

How does the canister work?

This explanation is based on an article from Motor Magazine or Motor Age that I can’t find anymore…
The canister is filled with high-grade charcoal similar to a gas mask. When fuel vapors expand out of the fuel tank, they cling to the surface of the charcoal.
The important thing here is that fumes don’t soak into the charcoal grains like most people think. This “small” fact is what makes the whole canister possible.
When the canister is purged fresh air is sucked thru the canister, which knocks the fuel molecules off the charcoal and caries them into the engine. Canister purge in older cars, including Fiero, is usually controlled by a ported vacuum signal from the carburetor or throttle body. In many newer vehicles the canister purge is controlled by the ECM/PCM.
If liquid fuel gets into the canister it will soak into the charcoal just like lighter fluid does in your grill. Once that happens the charcoal is ruined. Even if you could dry out the liquid fuel, the carbon won’t recover.

PCV system

The Positive Crankcase Ventilation system is both an emission control and a significant improvement to engine longevity. The job of the PCV system is to remove fumes from the crankcase and burn them. These fumes pollute the air and if not extracted from the engine they promote contamination of the oil and varnish on internal parts.
There are 2 major parts in the system, an air filter, and the PCV valve. Make sure both are clean and that the vacuum line(s) and vent hose are sealed.
The PCV valve should be replaced every couple years at most. There is a spring in the valve that is critical to proper operation. The spring will weaken over time. A bad PCV valve is hard to detect. The obvious test of shaking it only tells you it’s not stuck closed. It won’t tell you the spring is weak.
Make sure you clamp all the joints in the PCV line. The rubber parts can’t be trusted to seal themselves. Don’t over tighten the clamps or you will damage the soft parts.

Emissions Service Parts

Note: Be careful buying PCV parts for the 87-88 4 cylinder motors! Many parts books incorrectly list them as using the same parts as the older 4 cylinder engines. Double-check them against Grand Am or Olds Cutlass Calais of the same years.
I had a heck of a time finding the correct PCV filter for my DIS motor until I looked it up under the Olds line. I’ve noticed some parts catalogs also list ignition parts wrong as well.
This is a quick list of stuff I’ve seen listed and where. I’ve seen AC Delco emissions parts for DIS 4 at Parts America. I imagine they cover other years but I didn’t feel like checking them all. (I think the same vapor can is used in all Fiero.)
The part numbers for the DIS motor parts…

As far as I can tell, the AC EGR is an OE matched unit. (At least that’s the picture they have on their web site.)
GM Parts Direct lists the Vapor Canister for about $25. (Use GM # 17075840)
They don’t have the EGR valve.
No AC Delco part was listed for the one V6 I looked up. (86 GT) Because the V6 valve is ECM controlled it’s not as critical who made it as long as the new part is high quality and provides the correct gas volume.
If you can’t find a stamping number to use for universal EGR’s, try using the information listed with Niehoff Ignition’s parts. Here’s the info they list on Parts America for an 86 GT with their part # FE134A valve. (I’ve never use Niehoff stuff but there catalog info is handy. They are the only one I’ve seen so far that lists data like this.)
[E. G. R. Valve] OE Number 17085897; Orifice Number 11; Use EGR Valve Gasket {FE302}; Use EGR Tube Gasket {FE354}
Notice the OE stamping number above. You could use that bit of info for any universal EGR. (The one you have may use the same metering washer or a different one. Get that info from the chart that comes with the new EGR.)
The V6 EGR solenoid I found listed under “Vacuum Regulator Valve” in the Fuel Injection parts. Parts America says it usually ships in 5 business days.
AC DELCO 214-361 $102.99 [EGR Vacuum Regulator Solenoid Valve] GT, SE Listing
Everyone who’s got them likes Rodney Dickman’s catalyst kit. It has the needed stainless steel adaptors needed for installation.

I broke this out of the coolant fill article hoping more people would be made aware of the Stant catalog error.
Warning! There is an error in Stant listings, which means all catalogs listing Stant parts share the same error. The correct caps for Fiero are Stant part numbers 11230 or 10230 non-vented caps.
You want to use a 15-16psi cap as recommended by OE specs. There are 2 very important reasons for this. (We’ll get to vented vs non-vented in a minute.)
The radiator cap along with the coolant product determines the boiling point of the filled system. A 15psi cap increases boiling point about 45oF vs no cap.
Lower system pressure and the coolant will boil at a lower temperature.
The cap effects water pump efficiency and life by controlling cavitation. When you spin the water pump it forms areas of low pressure around the impeller.
This low pressure makes air dissolved in the coolant, and even the coolant itself, explode into bubbles. These bubbles cause turbulence in the water so it’s harder to pump. Cavitation also damages the water pump by giving the impeller a rough surface that reduces its efficiency permanently. Coolant under pressure is less likely to cavitate and is therefore easier to pump around the system. Life of the water pump is also increased.
There are low pressure, usually 13#, caps out there. They often get installed on old weak systems to prevent popping the radiator tubes, etc. These caps often cause other problems, like easy over heating, and should only be used as a temporary item. Long term use of these caps can cause damage to the water pump impeller. They are only a little better than a bad cap.

GM & AC Delco caps.

Thanks to “Two88GTs,” the current GM and AC Delco cap numbers for Fiero are:
Rad Cap
AC Delco: RC27
GM : 10409635

Thermo Cap
AC Delco: RC40
GM: 6410941

Water Water everywhere but not a drop to drink

Ok, we have a hundred articles about this in the forums. Why yet another one?
The basic procedure is all over the place but there’s a thing or three not in the various books or most of the forum replies. I only recently thought of this because I had to change the heater core this past summer. This modified procedure should help reduce some of the headache of filling a dry system and prevent lack of heat from a new heater core. I’ve also included some other cooling system information many people don’t know.

WARNING!¡! NEVER OPEN A HOT COOLING SYSTEM! Scalding hot water can and often will shoot several feet if you do this.
WARNING!¡! Ethylene Glycol antifreeze is POISON! DO NOT ingest or inhale it. Ethylene Glycol can cause kidney damage and death. If the cooling system has a leak that is producing a cloud of mist or steam leave the area until it dissipates.
NEVER dump coolant into septic systems or cesspools! The coolant can contaminate the entire system to the point it will have to be replaced.

How Toxic is Ethylene Glycol coolant?

• The Babcox article linked at the end of this page says 1 gallon of coolant can render 10,000 gallons of water unfit to drink.
• Accordng to The Sierra Antifreeze FAQ “Two ounces of ethylene glycol antifreeze can kill a dog, one teaspoon can be lethal to a cat, and two tablespoons can be hazardous to children.” (Before someone screams bias… The people who make Sierra also make Peak Ethylene Glycol based antifreeze. Read the links at the end of this page.)
• Propylene Glycol is less toxic than Ethylene Glycol but it still bad for you in large doses.
• Propylene Glycol is actually used in certain food products. (It’s the main ingredient in the coffee flavoring I use.)

What coolant do I use?

Brand doesn’t matter much. Whether you use traditional Ethylene Glycol (EG) based coolant or less toxic Propylene Glycol (PG) is entirely up to you. All of the name branded EG coolant presently on the market meets or exceeds the Fiero’s original requirements.
PG antifreeze does give up a small amount of freeze/boil protection but meets all requirements for corrosion protection and lubrication. The difference in freeze/boil protection would only matter for some cars. Most people will be unaffected by it. (Yes, I have used PG coolant and will likely use it after my next flush.)
The main thing is how it’s installed. Most brands of antifreeze recommend premixing with an equal volume of water, a 50/50 mix. You can go as high as 70/30 in really cold climates. You don’t want it thinner than 50/50 or the additives in the coolant will be too weak to do their job. Thicker than 70/30 and it won’t cool properly. (Too much antifreeze can make the car overheat.)
Read the package instructions to determine just what mix you want to use.
Don’t mix coolant types! Mixing the types won’t do any damage but it makes service a pain in the ass. Mixing Ethylene and Propylene based coolant will leave you with a system you that you can’t easily test later. The 2 coolants need different testing tools. The long life stuff will be degraded by regular coolant. Check the specific coolant maker for details.

DEX-COOL®

Note! For those of you who have vehicles with DEX-COOL in them, read this article at IMCOOL.COM. Also read the Babcox article at the end of this page.
They contain important information about the product.

What is DEX-COOL®

DEX-COOL® is Ethylene Glycol with an Organic Acid Technology (OAT) additive package and not a whole new coolant type. DEX-COOL® is made by Texaco for GM and is available in retail packages as “Havoline® Extended Life Anti-Freeze/Coolant DEX-COOL®.” Similar products using OAT or Hybrid OAT are now available through Ford Chrysler and others. I have no information on these other products and their compatibility with older systems. (DEX-COOL is a registered trademark of GM. Havoline is a registered trademark of Texaco.)

GM’s official position on DEX-COOL®

GM has informed dealers that DEX-COOL® may be used to fill cooling systems of GM vehicles built before the introduction of DEX-COOL®. However, the coolant service interval for those systems is to remain the same as published in the Owner’s Manual, I.E. the same as with traditional green antifreeze.
Source: Several GM TSB’s.
In other words, GM will not authorize the 5 year, 150,000 mile, service interval for older vehicles. Dealers are to continue using the 2 year, 30,000 mile, service interval.

Using DEX-COOL®

If you use DEX-COOL®, then heed the warnings in the IMCOOL article. Use only the Stant non-vented cap or equivalent. Before using DEX-COOL®, the system must be flushed thoroughly, including cleaning out the recovery tank. GM has decals and different lids for the recovery tank to indicate DEX-COOL® is being used. I do not know if there is a lid that fits the Fiero tank.
Make sure the DEX-COOL® is never allowed to become weak. Low coolant concentrations are known to form sludge in the system. Presently, no one seems to know why this happens. GM recommends DEX-COOL be kept in the 50% to 65% range for proper operation.
DEX-COOL® should not be mixed with other antifreeze products! Mixing regular antifreeze won’t cause damage but will cut the service interval to 2 years, 30,000 miles.

Would Ogre use DEX-COOL®?

Probably not. I don’t think it’s a bad product. I’m just not interested in the hassles involved with converting and maintaining it.
One issue is the Fiero coolant tank can collect allot of trash. According to the IMCOOL article, that trash will cause problems for DEX-COOL®. I don’t have the time to fool with making sure that the DEX-COOL® won’t get contaminated.

New long life colants

Prestone® “All Makes All Models Extended Life Antifreeze/Coolant” claims to eliminate guesswork with their new coolant product. Others are sure to follow.
Do these products work? No idea. I would guess they are still Ethylene Glycol based products so don’t plan on using them in Propylene Glycol (Sierra) loaded systems.

Water

The source of water you use does matter. It effects the life of the coolant and the system as a whole. Use the cleanest water you can.
Never use “softened” water. Softener units add salt to the water that can cause damage to the cooling system.
Tap water commonly has a high mineral content, Chlorine, and other chemicals that are bad for the system. Consider buying deionized bottled water to mix with coolant. Deionized water is just below Distilled water on the clean scale.
You can get it in allot of grocery stores. Deionized and Distilled water are usually in the beverage or laundry isle. (It’s often sold for people to use in their irons.) This water won’t cause hard water scale or react with chemicals in the coolant.
If you have a home “Reverse Osmosis” water filter, you can use it to fill the system. Keep in mind an RO system takes several hours to fill its tank. Store up 2-3 gallons ahead of time. That way it’s ready to go.
There is some disagreement between coolant makers. Some say tap water is ok while other’s say use Deionized or distilled water. I’d say if you aren’t sure of the water comming from your tap, use the deionized or distilled. Deionized water isn’t very expensive and clean water is always going to be better for the
system.

Premixing Coolant? What the hell is that?

If you have just flushed the system then DO NOT use premix coolant. See the filling section for details.
It’s not a difficult thing. It’s a hell of allot easier to do this now than try to adjust the coolant once its in the car. You’re going to need around 3.5 gallons to fill a dry system plus it gives you some properly mixed stuff to fill the coolant recovery tank with later. (Note: Several coolant makers have their product available straight or premixed. You should not alter premixed products.)
All you need is something so you can measure with and a 5 gallon container.
The coolant makers recommend a 50% mix for most cars. A 50% mix of most brands of coolant will prevent freezing to -34(-37C) and has a boiling point of 265F(129C) with 15psi cap. You can add more coolant, up to 60-70% to get more antifreeze protection.
If you live in a hot climate, you can use Redline WaterWetter and cut the coolant to 20-30%. You have to use some coolant in case you get a cold snap.
You also have to protect the heater core from being frozen by the AC system in many cars. WaterWetter contains additives to make up for the low antifreeze amount. Before you do this, read the bottom of Redline’s WaterWetter page carefully. You must always use enough coolant to prevent freezing in your local climate or anywhere that you’ll drive to.
NOTE: The maximum amount of coolant allowed varies by maker. Read the package or see the maker web site for details. Adding coolant beyond the maker’s specs won’t help anything and can hurt cooling system performance.

The same table works for metric. Just change the word gallons to liters and multiply everything to get the quantity you want. This is one of the few times no odd fractions are involved. Even US readers can use liters when mixing small volumes to top off the system or fill the recovery bottle.

Storage

First off keep it in a plastic container. When most antifreeze is left standing it will settle to the bottom of the container. This will leave plain water at the top that can start corrosion in metal containers.
Second make sure you stir it up before you use it. If the container wasn’t sealed well check it with a tester to make sure it’s still the mix you want.
Third many antifreeze products have a shelf life. The additives in them can spoil over time even if the coolant has never been mixed or used. For example Texaco claims DEX-COOL (AKA Havoline Extended Life Anti-freeze) has a shelf life of over 8 years compared to their regular products which have a shelf life of around 18 months.
These separation and spoilage issues are part of why a car left stored for a long time often looses the water pump shortly after they are taken out of storage.
It’s not the only factor but it’s a big one. The problem can also contribute to failure of the radiator and heater core.

How do I drain the system?

You’ll need a catch pan and a 5 gallon pail. One of those pumps you can run with a power drill is really nice. With that you can pump the coolant to the pail and not spill it all over. Even with a pump, you’ll need the pan to drain the under car pipes. (The drill pump works really great if you have to use old jugs to collect the waste coolant. Beats the hell out of a funnel.)
Remove the filling cap on the engine. Leave the cap on the Radiator. If you take both off at the same time, you’ll dump around a gallon of coolant all over the place. (The check valve on the radiator cap will open when the radiator starts draining. It should also siphon out most of the recovery tank this way.)
There is a petcock in the radiator that you open to drain most of the system.
Once coolant has stopped draining from the radiator remove the plug from the rear of each coolant pipe under the car. The plugs are just behind the doors.
There are drain plugs in most engines but they are giant pains to get out. Even with the plugs out you often can’t drain it dry. Flush the old coolant out until the water drains clear.
Don’t forget to empty and clean the recovery tank! That thing gets amazingly filthy.

How do I fill my cooling system?

Important Update…

This document was originally written as if you would be filling a dry system.
(Like you just changed an engine or something…) If you are filling a system that has been flushed, you now have plain water trapped in the engine and heater core. If you add premixed coolant to the system the trapped water will dilute and weaken the antifreeze.
This update was added because I was reminded by the IMCOOL.com article linked above that allot of people, including people who should know better, forget to consider flush water when refilling the system. This apparently has been a large problem with DEX-COOL but it’s a problem with any coolant. None of them will work properly if they are weak.
The whole point of flushing was to eliminate weak coolant and dirt. We certainly do not want to install new coolant only to dilute it below spec. That would leave the coolant too weak to properly protect the system, defeating the large amount of work you just did.
To account for the trapped water:

1. Drain the under car pipes and radiator after flushing.
2. Find the total system fluid capacity. (Approximately 14 quarts for all Fiero models.)
3. Divide system capacity in half and pour this amount of antifreeze into the system. (Approximately 7 quarts of new antifreeze for all Fiero models.)
4. Fill the rest with water. (De-ionized or Distilled water is preferred.)

This will eliminate the problem of trying to figure out how much water was trapped in the system after flushing. The rest of the filling procedures do not change! Don’t forget to fill the recovery tank with 50/50 premixed coolant.

Moving on…

My method is longer than the ones most people use. I’ve developed this based on filling many other systems and the special needs of Fiero. It takes longer to do this way but it solves several issues all at once. While it can be used during any fill, this procedure was developed for filling dry systems or systems where the heater core has been worked on.

1. Remove the front and rear filling caps. Pull the thermostat out.
2. Pour premixed coolant into the rear cap until the radiator is full. ((Filling from the back helps push air bubbles out of the coolant pipes under the car.))
3. Cap the radiator when it is full.
4. Fill the coolant thank to the “add” mark with the same mix you are using in the rest of the system. Remember the tank says check hot… We want to leave room in there for coolant to expand out of the radiator.
   • Here’s where most procedures being used leave out an important item. Air bleeding the heater core. If this isn’t done you might never get all the air out of it and that will reduce its heating capacity considerably. It’s also a likely cause of people having a hard time getting all the air out the thermostat cap. The heater core and hoses can trap allot of air.
   • This part is allot easier with 2 people. If you’re by yourself fill the back then vent the heater. If you are starting from dry then you may need to go back and forth a couple times.
5. Carefully move the top hose clamp out of your way and loosen the hose. Don’t pull on the hose. If it is stuck make a hook from some thin rod or bar stock and work it under the hose to loosen it. Pulling or twisting on the hose can crack the solder joints at the heater core tank.
6. Once the hose is loose work it slowly off the core tubing to let the air out of the system. If need be add coolant to the back until the heater fills. Try to hold the hose as shown below. You want to keep the opening as small as you can to eliminate as much air as possible without spilling coolant all over the place.
7. When the air is gone put the hose back and clamp it in place.
   • This will eliminate the vast majority of air from the heater core and its plumbing. It should make heater core replacement and filling the system from

     dry allot less of a headache.
     Now we’re back to filling in the rear. This varies a bit from person to person just what the best method is. Here’s what I do on mine. Don’t forget to keep checking the recovery tank. If you let it run low air will be pulled into the radiator when the system cools.

8. Fill the engine until you reach the top of the hose connected to the thermostat housing.
9. Start the car and let it run with the thermostat cap off. This will burp out the big air bubbles. Leave the car running until step 14. (Some cars hate having the cap off. I don’t know why. If yours is like that then just put it on. Just don’t let the thing warm up and build pressure. You only need it to run a minute or two. You may have to stop and check it several times. read on for more notes on this step.)
10. Pour in more coolant mix if the level drops below the top of the hose.
11. Once the engine stops spitting up air put the cap on.
12. Run the car to normal operating temp. This will happen fairly quickly unless the fan is on.
13. Let it run a few minutes. Keep an eye on the temperature to make sure you don’t over heat. If you have an ECM scanner hook it up for this. Watch the coolant sensor. If it warms up then drops, or fails to warm up, shut off the car. You likely have a big air bubble in the thermostat neck. (This shouldn’t happen but it’s something to watch out for. Gives you one more thing to use your scanner for.)
14. Shut it off and let it cool.
15. Open only the rear cap to check the system and top it off.
16. Install the thermostat now and cap the system.
17. Run the car to operating temp
18. Check the overflow tank. Fill it to the full line.
19. Shut off and let it cool.
20. Check the level in the engine again. It should not need more than a little bit if any.

Some air will always be trapped in the radiator. This is normal for side tank radiators. Most of it will work itself out through the coolant recovery tank. It is critical the recovery tank is never allowed to run low on coolant. If it gets too low air can be pulled into the radiator. Not a good thing.
Some people claim that it helps to have the car parked on an incline or jack it while filling. I’ve never found that necessary myself but it’s one more thing to try if you have trouble.

More on Step 9…

The trick with opening the cap with the engine running is that the Tstat has to be out and you don’t start the car with the cap off. (DO NOT even think about this on a hot engine!)
With the engine running at idle for a few seconds to get the water all moving, you can often open the Tstat cap and watch the water flow by. It may only work on the L4. It also won’t work if there are any problems in the plumbing like a partly blocked radiator or a crushed pipe under the car.
If you try to start the car or hit the throttle then water will go all over because of simple inertia. The sudden change in pump speed creates a spike in one part of the system. It takes the coolant some time to catch up thru the whole system.
The nice thing is when the cap off trick works you can just add coolant as the level changes. If the cap off trick doesn’t work then just run the engine 20-30 seconds to kick the air bubbles out of places and check the level. Once most of the air is out then run the engine to full heat and let it cool. Check the level in the back only. Do NOT open the front cap after this or you’ll let air into the radiator.

The thermostat cap keeps sticking…

This is annoying to say the least. To prevent sticking and rust, clean the thermostat neck and coat the rim with a silicone product like Brake or Dielectric Grease. Coat everything the cap touches or covers. Thes silicone products won’t wash out easy and it won’t damage the rubber seal on the cap.

What radiator cap do I use?

Warning! There is an error in Stant listings, which means all catalogs listing Stant parts share the same error. The correct caps for Fiero are Stant part numbers 11230 or 10230 non-vented caps.
Most of this section was moved to the article on caps. I left the numbers here for easy referece.

GM & AC Delco caps.

Thanks to “Two88GTs,” the current GM and AC Delco cap numbers for Fiero are:
Rad Cap
AC Delco: RC27
GM : 10409635

Thermo Cap
AC Delco: RC40
GM: 6410941

“The p/n for the RC27 in my parts book is 10036879 which is still a valid number in the GM parts system but it is for the OLD design cap, and the remaining stock is indeed OLD. Get the 10409635.”

Stant Catalog Error

Somewhere along the line the Stant catalog got messed up. This shit happens in the auto parts business. Whether the mistake originated from GM or Stant I doubt anyone really knows. Unless GM tells Stant the catalog is incorrect, which isn’t likely, the error will probably never be fixed.

Why does antifreeze go bad?

Actually Ethylene Glycol and Propylene Glycol don’t go bad. It’s the additives that lubricate the water pump and prevent corrosion that wear out or spoil not the coolant base.

Lube the pump?

More correctly the pump seal. The bearings are sealed and not exposed to coolant. There are additives in most coolant products that preserve/lubricate the seal and they go stale just like the anti rust additives.

Why recycle?

Ethylene Glycol is extremely toxic. It can cause irreversible kidney damage or death. In addition used coolant can contain lead and other toxic compounds.
These need to be kept out of the environment as much as possible. Coolant must never be dumped on the ground where animals or children may ingest it.
Used coolant can be used to make new coolant at relatively low expense.
Basically the used coolant passes through a machine where the EG is filtered and separated from the water and other contaminates. A new additive package is added to the recovered EG and it is ready for use.
Many areas now ban dumping used coolant into the sewer system.
NEVER dump coolant into septic systems or cesspools! The coolant can contaminate the entire system to the point it will have to be replaced.

Where can I take it?

In many cases you can return waste coolant to the large chain service centers like Pep Boys and K/Wal-mart. Some small shops with their own recovery machine may also take it. Exactly who will, or is required to, accept used coolant varies by city/state. Contact your city/state waste authority or state EPA. Most of these agencies are now on the web. In the U.S. you can often get to them at www.state.XX.us just put your state’s postal code in place of XX.

Is recycled coolant safe?

Note: Only Ethylene Glycol is currently sold as recycled antifreeze.
It is perfectly safe for the car as long as it is processed correctly. The key words are “processed correctly.”
If you are buying the recycled coolant as retail packaged product it should not be any less reliable than new coolant. Retail products should all meet current new car guidelines for antifreeze. Read the package for specific details.
The ones to watch out for are repair shops and salvage yards. There is little or no oversight of this market segment and there have been problems with them.
The main issue is that the recycled coolant may not meet requirements for additive replacement. These additive packages provide the lubricant for the water pump and corrosion inhibiters. Without the correct amount of additives, the coolant will be free to eat the system.
If you were buying the coolant from a small packager, like a salvage yard, it wouldn’t hurt to ask questions like what additive product was used in it. If they won’t answer your question or you aren’t comfortable with the answer then you might want to shop elsewhere. If they tell you no additive was mixed in then you would have to buy that and add it yourself. At this point the recycled coolant can get to be more trouble than it’s worth.
If you are having cooling system work done ask what coolant is being put in the car. If they tell you they are recycling your coolant then ask what brand additive package they are using. Treat this like a small packager above.
No, I’m not saying all coolant recycling in small shops is bad. I’m simply saying you need to be aware of who is doing it. The Quality of on site coolant recycling is only as good as the people doing the job and the condition of their equipment.

Installation

How hard is that? You just shove it down the hole… They should all be this easy.
One small thing people over look… When installing Fiero or similar thermostats, coat the O-ring on it with a film of petroleum jelly or better yet, silicone oil/grease. Dielectric compound and brake grease are both good. You only need enough to leave a film on the ring.
If you don’t lube the O-ring, the coolant usually isn’t slick enough and the thermostat won’t want to seat or you tear the O-ring. I suspect this is how many thermostats end up bent.
You have to use firm pressure, and sometimes a little wiggling helps, but you shouldn’t have to force them down the hole. When it’s fully seated, the frame will not obstruct the cap. If a lubed thermostat won’t seat, suck out some coolant and inspect the neck. Look for corrosion or dents in the seating area.
Push in the thermostat and see if the neck is out of round.
You’ll also find it easier to install the cap if you put a film of lubricant on the rim of the thermostat neck. That will let the rubber slide easier and help prevent corrosion.
If the rim is corroded, clean it with fine sand paper and coat all the cleaned area with silicone grease. (Dielectric or Brake grease) The silicone won’t easily rinse away like most petroleum products and it won’t react with the coolant or the cap. Paint could actually bond the cap on. You should probably replace the cap. A corroded rim often damages the seal.

Alternate Thermostats

There have been a number of questions regarding the use of alternate thermostats in Fiero. Here’s a bit of data.
A thermostat is required for all EFI motors to operate correctly. It’s not an option any more. An EFI system without a thermostat will have problems. Fuel Mileage, performance, and reliability will all be affected.
There are 3 thermostat choices commonly used. Others may exist, but are custom work. Additionally there are some things to keep in mind when selecting a thermostat. For the purpose of this article we’ll lock the radiator fan on full time. That way we know the air is always moving, and that only the thermostat controls the temperatures we are seeing.
There are a couple different temperatures we are concerned with monitoring when we work with thermostat selections. The first is obviously the thermostat set point. Set point is the temperature when the thermostat is fully open. The second is not as obvious, and requires a tool.
This second number is the engine temperature reported to the ECM. There are 2 reasons we need to know the ECM temperature reading. First is that the engine will not operate properly unless the ECM thinks the block is within a specific heat range. Second is that the ECM reading and the Thermostat set point is never the same thing. The ECM sensor will typically be reading temperatures 10-20 degrees above the thermostat value.
So with all that in mind we have a table of data that end up looking like this.
Your choices for a stock programmed ECM/PCM are usually 180′ or 195′. The car makers all install 195′ at the factory for fuel efficiency and emissions reasons.

What does a lower temperature thermostat do?

Well for one thing, because the engine doesn’t run as warm with a cooler thermostat, the intake manifold stays cooler and keeps the intake charge cooler. The cooler charge is denser so more air/fuel mix fits in the same space.
If more air and fuel can enter the cylinder then the engine makes more power.

Why does the 160′ thermostat require reprogramming the ECM?

Because the 160′ thermostat can keep the block temperature so low that the ECM thinks the engine is cold. When the ECM thinks the engine is cold it will run in Open Loop mode. In Open Loop mode the fuel/air mix is not at optimum, and while you may get a bit of performance, you waste allot of gas. In Open Loop mode the engine will always run a little rich. This rich mix is chosen because a lean mix can actually destroy the engine. The requisite PROM change reprograms the ECM to use Closed Loop mode at a lower temperature. This problem is caused entirely by the thermostat. Using a low temp fan switch with a 180′ or 195′ thermostat will not cause ECM problems.
Just how much reprogramming may be needed depends on the specific setup and the ECM involved. In some cases the ECM may tolerate the 160′ thermostat without reprogramming. The only way to be sure of this is to monitor the ECM data stream in real time.
So if you want a couple really cheap HP, try a 180′ thermostat. They are only about $9.00 and you can get them almost anywhere. It’s only going to give you a small boost, you might not even feel it, but hey, what do you want for $9?
In addition consider one of the alterations to the radiator fan that will either turn it on sooner or lock it on whenever the key is in run. This will insure that the thermostat is the only thing controlling engine temperature resulting in much tighter temperature regulation. It rather defeats the purpose of installing a low temperature thermostat if the fan isn’t activated until 235′. (87-88 L4 activates at 225′.)

Why does the ECM sensor report higher temperature than the thermostat set point, even when mounted in the thermostat housing?

While the value of the thermostat is one temperature, the temperature of the sensors and block are often something else.

• The coolant is always a little hotter than the thermostat value. Remember thermostat value is just the number at which the thermostat is open. It’s not the actual temperature of the coolant.
• The engine speed, vehicle speed, and fan activation, all affect the engine cooling. Low air or coolant flow will quickly increase coolant temperature above the thermostat value.
• The cast iron itself is not a great heat conductor. Areas not in direct contact with the coolant will be hotter than the areas that are touching. Dirt and corrosion in the block add to this.
• Coolant flow is different throughout the block. Some of this is intentional some is not. There is only so much space to make into water jacket and not make the head or block very weak.

Tstat collapse

This is an odd problem that has come up a few times now. I think in most cases the Thermostats are being damaged during installation. After rereading some threads and update posts by a couple people I think there’s another factor, plugged or damaged heater plumbing.
Something many people don’t know, and many of the rest of us forget, is that the heater and cooling system are parallel circuits. The Thermostat regulates flow to the radiator. When the system is cold, and the thermostat closed, all the coolant flow is thru the heater. If the heater is blocked, that pressure has to go someplace.
Below is a typical plumbing map for a cooling system. In the real world, the heater can be fed from almost anywhere on the engine. For TBI and Carburetor motors, it’s common to feed the heater from an outlet on the intake manifold.
This is how the Fiero DIS L4 motor is done. The outlet on the manifold also allows heating the intake to prevent fuel from pooling below the TBI. I’m not sure where the heater outlet is on the V6.

If you’re lubing the thermostat O-ring etc, but the thing still collapses, try bypassing the heater core. Also check under the car to make sure nothing whacked the heater plumbing.
It’s actually a good thing that the thermostat can collapse when the engine is over pressured because of a heater problem. Otherwise you’d have something break, which happens in other cars. As it is, this could also be part of why people are having problems with durability of the water pump. With the size of the Fiero cooling system, it wouldn’t take much to overload the pump.

All documents in this area are Copyright 1999,2000 D.W.Lane All rights reserved. Not for reproduction in any media without written permission.

EEK! They crushed my pipe…

Crushed coolant pipes on Fiero are extremely common and the amount of damage is not always obvious. These pipes must be checked for damage any time you are having overheat problems.

How bad can the damage be?
Below is a photo of one of my pipes after a local tire shop ruined it.

At fist look the bend doesn’t look very bad. However when you drop the pipe and look…
The pipe is crushed almost completely shut.
When looking for pipe damage, always check the area from the rear support back very carefully. That section of pipe should be straight. If the section between the support and drain bung is bent at all then drop the pipe so you can see the top.

Why does this happen?

Some fool almost always causes damage to the cooling pipes with a jack or lift.
Running over road debris could do it but most times it’s a jackass with a jack.
The biggest problem is that there is nothing structural in that area. The rocker panel is just plastic and odds are good they will wreck that to.

How can I protect the car/pipe?

There’s not a huge amount you can do but some things help.
· I only buy tires and stuff where I can see them work on the car. Places like NTB where I go into the work area. You have to watch all chain service places like a hawk. Even the ones that claim everyone is ASE certified.
· Watch the temp gauge as soon as you leave any service place. If they have crushed the pipe you will probably run hot or even over heat very quickly. I didn’t get 3 miles with the pipe above. (The car was already warm.) I was able to get back to the shop with the heater on full. (It got just enough additional cooling to prevent boil over.)
· IF you start to overheat, return to the service center AT ONCE! Don’t let it go even a day or they could fight you on it and win. The burden will be on you to prove it. The longer you let it go the harder that will be.
The first picture I took above was taken on their alignment rack before I left the place. It comes in really handy to carry a camera at al times. (Many car insurance carriers recommend this anyway.)
One idea I’ve been playing with… Building some type of guard I can attach next to the pipe. Then the guard can take the jacking instead of the rocker and pipe. I haven’t had time or material to mess with that yet.

Repair

Ideally you want to put in a new pipe that isn’t bent but that isn’t always an option. I had to put a section of rubber hose on mine.
If you go the hose route… be VERY careful! The hose will blow off easily if the clamp is at all loose. Check it regularly. (Yes, I had this happen a few months after the repair.)
As soon as I get a chance, I will epoxy a wire ring around the pipe. This will give it a ridge like at the normal hose fittings so the hose can’t blow off. It can still leak but will be much harder to blow off.
You will also need to support the back section of the pipe in many cases. There are a few ways to do that. On the pipe above I ran a heavy wire from the clamp that hold the hose to the thermostat neck (L4) and hung it from a bracket that supports the fuel vent line.