Water Water everywhere but not a drop to drink

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.


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.


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.


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

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.


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.


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