Please be sure to read my other posts below. Something is not right after changing the coolant, and now my car has overheated!



Original post:


OK ... as I am typing this, I am in the middle of changing the coolant on my '98 coupe. I have questions related to the instructions that appear in multiple threads on this board.

For the instructions below, how long am I supposed to wait before opening the surge tank cap after running the engine to 210°F? Does it need to be opened hot to help "burp" the system, or can I let the engine cool between each opening?

A fast answer is needed here, so thank you in advance for your help.
LO PHAT


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Park the vehicle on a level surface.
Follow the steps below to remove the radiator surge tank fill cap:
Slowly rotate the cap counterclockwise1/4 turn and then stop. Do not press down..
Allow any residual pressure, indicated by a hissing sound, to be relieved.
After all hissing stops, continue turning counterclockwise to remove the cap.
To tighten the cap, use hand tight pressure only.
Open the radiator drain ****.
Allow the system to drain completely.
Fill the system through the surge tank opening.
Start the engine.
Idle engine for 1 minute.
Install surge tank cap.
Cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F).
Shut off the engine.
Refer to step 3 above to remove the surge tank cap.
Start the engine.
Idle engine for 1 minute and fill surge tank to 1/2 inch above COLD FULL mark on the radiator surge tank.
Install the surge tank cap.
Cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F).
Shut off the engine.
Top off coolant as necessary, 1/2 inch above FULL COLD mark on the radiator surge tank.

 

I'm going to be needing to do this too.

Have you thought about or does anyone know about having the system completely flushed by a dealership or jiffy lube or something. Seems like this "flushing" would remove all of the previous mixture so a new one can be added.

 

While I'm waiting for a reply to my question(s), I might as well answer yours. I've been researching and pondering on this issue for the past two weeks now. Basically, if your coolant is discolored (or not DEXCOOL), you would do well to have a complete system flush done.

After considering the various costs involved (plus the fact that I never trust any dealership or service center not to damage my car), I opted to spend under $20 (distilled water from Fry's and Prestone DEXCOOL from Checker) and drain what I could myself. I managed to get over two gallons out, so that is 2/3 of the system's capacity. Not too bad in my book....

Some feel that you should at this point keep filling and draining the system with water (running the car to operating temp each time to open the thermostat) until the system drains clear. I chose not to do this, however, because I don't want to introduce the minerals in tap water into my car's system. Instead I'm going to simply flush what I can of the system every year or two by draining the radiator and overflow tank.

Hope this helps,
LO PHAT

 

Hello? Anyone?

Since there have been no replies yet, I'm opening the system about every 20 minutes (giving it time to cool). I'm not so sure this is the right way to do it, however, because I've yet to get the two gallons of coolant back in....

How will I know when my system is free of trapped air (ie "burped")?!

LO PHAT

P.S. What exactly does the part about "cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F)" mean?

 

H E L P ! ! !

Something isn't right here. Over the course of the past few hours I got the 2 gallons back into my car's cooling system following the instructions provided on this forum. I just took my car down the road, and within 1/4 mile it was at 240°F. By the time I got turned around and eased the car back home, the temperature was over 255°F and I was getting the warning message on the DIC.

What has gone wrong?!?!

LO PHAT

 

Hey there .... a few things to keep in mind .....

1) tap water (unless your local supply is known to be heavy in mineral content) isn't a problem for the car ...... the factory uses "Bowling Green" tap water when it initially fills your engine ..... you had a little bit of Kentucky driving around with you until you flushed the system ....

2) the "burping" process isn't as difficult as some procedures make it out to be ..... and in fact ones that tell you to get the engine temp to 210 degrees are possibly dangerous .... with the coolant under pressure it will not boil until it reaches something like 265 degrees .... when you remove the pressure cap on the reservoir .... ANY coolant at 212 or above will boil instantly with the pressure release ... possibly expelling hot coolant on you.

3) Best way to "flush" the system is to run tap water through it until it "runs clear" .... now you know the cooling system holds 12.6 quarts (call it 3 gallons) so the best thing to do after the flush is to seal the system back up and add 1.5 gallons of Dexcool to the system (through the surge tank). Now all we need to do is add water after this.

4) add water until surge tank shows full to the HOT line.

5) Go out and drive the car for a few minutes (enough to open your thermostat ... a stock thermostat will open at about 185 degrees .... drive at least far enough to get the coolant past 185 ... don't drive so far that you risk overheating the engine.

6) Let the coolant cool .... could even be overnight .... then add water to the reservoir to again reach the HOT level.

7) Drive the car .... as soon as it reaches the thermostat opening temp ... pull over with engine running and look at reservoir ..... you should see bubbles and Dexcool coming into the reservoir ..... if it seems the reservoir is dropping quickly .... turn off the engine (unlikely). Let the reservoir stabilize. Again it can sit overnight if you want.

8) Third time, add water to 1/2 way between COLD and HOT lines .... you can check for a couple of days aftter this ... but basically the system (unless it has a leak) should stabilize at this point.

 

Leave the cap slightly loose while you're "burping" it, so pressure will not build up and trapped air can escape. This will also allow you to add additional coolant while it's still hot.

Bring it up to 3000 rpm quickly,and then back to idle. Wait 30 seconds
before you repeat this again.

Raising the front end up higher on ramps or stands, will also help the "burping" process.

 

Thank you for the replies, guys. Overall I'd say that I did everything correctly and per the instructions as well as your recommendations (except, of course, waiting all night for the coolant to completely cool). Something has clearly gone terribly wrong here....

Why did the car overheat? What sort of damage (coolant degradation, oil degradation, etc) likely took place?

I just started it back up again (it sat for over an hour). The coolant was down to about 138°F, but it climbed to 220°F in under three minutes. At that point I shut the car off.

I need your thoughts and suggestions on this.

LO PHAT

 

I have now spent the majority of 10 hours today working on my car's cooling system and researching everything there is to read in these forums about the subject. I'm at a total loss, and my car (which is my daily driver) cannot be driven. It takes only minutes for the temperature to hit 230°F or more.

Here are some of the many questions I now have:

1) Did the engine really hit more than 260°F, or is there an air bubble somewhere in the cooling system giving false readings?

2) THIS IS A BIG ONE: If the engine did hit over 260°F, what damage has been done?

3) What could possibly have changed between yesterday (the cooling system was working fine) and today (I drained and refilled it)?

4) How should I go about making sure that the cooling system is properly "burped"?

5) Before I start throwing a bunch of parts at the car (new thermostat, new water pump, new radiator, etc), how can I troubleshoot this issue? (a note here: I did rule out the pressure cap by replacing it with the one from my Z06. There was no change, and I had to shut off the car when the engine quickly climbed over 230°F again.)


I'm sorry for posting so many times in one day, but I really need some help here....

LO PHAT

 

It sound like you still have trapped air in the cooling system.
Here's another thing that you can try, to get it out.

With the engine not running and COOL, disconnect the small coolant hose at the throttle body. Make sure the surge tank is at the full mark, and leave the cap off. Let some coolant drain untill you see no air bubbles. Put the hose back on, top off the coolant, and then run the engine up to temperature with the cap still OFF.

I doubt if any engine damage was caused by the brief overheat.
There are built in safeguards, in the "Reduced Engine Power" mode,
that protects when an overheat occurs.

 

OK ... the ONLY thing you did was drain coolant from the radiator drain plug ..... and you got roughly 2 gallons of coolant out and put 2 gallons of coolant back in ??????

If the above is true ..... sounds like you have a coolant circulation problem......

Start engine and CAREFULLY (stay away from moving engine parts and fans) check the temperature of your upper and lower radiator hoses .... what we are looking for is something like both hoses being cool while your temp gauge says the engine is hot .......

Are the cooling fans coming on when the engine gets "HOT" ?????

Does the serpentine belt appear to be driving the water pump correctly ??? Be certain the pulley on the water pump is turning, and that it doesn't appear to be wobbling .....You didn't remove or change the belt during this drain process ... did you ???

It is hard to picture that you have an "air bubble" in your system that hasn't "burped" out.

Sounds to me like a circulation problem .... either the water pump isn't driving the coolant properly ..... or the thermostat has failed and is blocking coolant flow to the radiator (it's supposed to fail "open" ... but ????) which is why you should ccheck the radiator hoses ... that will tell us if there is a circulation problem .....

Possible you have a blocked radiator ... but I can't see how it could have blocked from a drain procedure .... was the coolant that came out a "clear" orange color ...... or was it muddy and sludgey ??????

Do you have access to an InfraRed temperature "gun" ???? that would help immensely in tracking this problem down ..... would even show if the ACTUAL engine temperature was as high as the GAUGE temperature .... there is the remote chance the ECT (Engine Coolant Temperature) sensor went south on you .... but usually it would "fail" ... not show incorrect and varying temperatures ....

Post back on what you find ....

 

That is correct. I got just a little over two gallons out (by first draining with the nose on ramps and then lifting the car's rear to level it) and got just a little over two gallons back in over the course of about four repeats of the instructions on this forum.

I checked all of the above while working on the car and refilling the cooling system. Both hoses are getting hot ... I'd say the lower hose often felt hotter than the upper hose (but this was when letting the engine temp reach only about 220°F before shutting it down). The cooling fans are working correctly. Everything appears to be normal with the water pump and pulleys, and I didn't do anything with them or the belt during this process anyway.

I would have to agree, but I'm praying that this is the case. I took the car around the block this morning and then let it idle up to operating temperature. It mostly stayed around 192°F. At one point it climbed to 226°F, but then it fell back down around 210°F.

What exactly should I be checking for on the hoses? Which hose (if either) should be cooler than the other? I can't see how a circulation problem that never existed before suddenly appeared unless the thermostat failed in a closed position (which was one of my thoughts). However, after this morning it would have to be working again, which makes me skeptical of a failure.

I would best describe the coolant that came out as "burnt orange" (orange with a faint hint of brown in it). It wasn't really muddy or sludgy (maybe a little muddy ????), but it wasn't as bright an orange as the new coolant either.

I do have a temp gun, and I wish I had thought to use it yesterday. I also wish that I had thought to check my radiator hoses as well as the engine oil temp right after the engine overheated at over 260°F. I will check all three things if it happens to overheat again.



I've been praying hard on this one, and here is my big question in all of this: If it was air trapped in the system, did I likely get a faulty reading or would the engine really have overheated?

If the engine did overheat, what sort of things should I be looking for at this point? Should I consider changing the oil or flushing the coolant again? More than anything I want longevity out of this car, so I need to be certain that anything small now doesn't have the chance to do long-term damage or become something bigger later....



Thanks guys,
LO PHAT

 

I gotta say I like your attitude ..... you're giving us GREAT feedback, and you are "concerned" about all the right issues ....

Here's my thoughts .....

1) I agree with Quicksilver Vert 01 that it is EXTREMELY unlikely you did any damage to the engine ..... in fact unless you saw the DIC message warning that the PCM was going into "ENGINE PROTECTION MODE" then the PCM does not consider the engine to have overheated. IIRC there is a DTC set in the PCM if it does go into "PROTECTION MODE" so you could check and see what DTC are set. You can read more about this mode in your Owner's Manual. Basically it allows you to drive the car up to 50 miles with no coolant in the engine. This was a feature first introduced by Cadillac, and an auto magazine decided to "test" this feature. They took a Cadillac and drained ALL the coolant from it. They then drove it 500 miles (the manual says to only go 50) in PROTECTION mode, and then had the engine torn down to see what damage had been done to it .... the result ??? NO damage ..... a great technology.

2) Coolant flow through the radiator is as follows ..... HOT coolant leaves the engine and flows to the TOP LEFT side of the radiator. The coolant then flows through the radiator and COOL coolant leaves the radiator at the RIGHT BOTTOM of the radiator. So the upper hose should always be hotter than the lower hose ..... unless the car is just idling and the fans have not kicked on yet .... in which case they will be pretty close to identical in temperature. The lower hose should NEVER be hotter than the upper hose.

3) At this point it sounds like your coolant is working OK. I'd recommend you do the following ..... check the coolant level in the reservoir to be sure it is at least above the MINIMUM level, maybe even mark the level with a grease pencil or some other mark you can erase easily. Then take the car and do a "highway run" .... get out on a freeway or highway and do at least a 10 or 15 minute drive at legal speeds ... 60 ... 65 .... 70 ... (obviously watching your temp gauge) then come back home and let engine cool. Check level of coolant once engine has cooled again. If the level has dropped, you are still getting air out of the system .... if the temps and level were normal during and after the run ... I'd say you got all the air out.

4) As Bugs Bunny would say ... unlax .... you haven't hurt the engine. It sounds like the "problem" is probably fixed. Next time you do a flush consider this .....

* After the first "fill" of coolant, fill the reservoir to the top and instead of just letting the car sit and idle, take it out and drive it around the block until the ECT hits about 200 to 220 .... then park the car and let it cool. The reservoir will probably be pretty low to empty at this point. Once the engine has cooled (couple of hours with the hood open) top up the reservoir and do another "drive around the block until you are dizzy" .... I'll bet that second drive will lower the reservoir, but it won't empty it. The cooling system seems to prefer being "driven" than just sitting idling ..... it gets air out more efficiently with a "high flow" rate than a "low flow" rate.

unlax dude ... You haven't done anything wrong .....

 

Had the same problem with trapped air.

Here's what I did: Start engine, put rag around upper hose at thermostat housing, then CAREFULLY squeeze hose clamp with pliers and wiggle hose till you hear air escaping ( For me this purged majority of trapped air)

Release clamp, and let engine idle. Watch coolant tank and you should see air bubbles rising from bottom. When bubbles quit, you are good to go. Top off tank after engine cools down. My coolant level is about 3/4" inch down in visible area of tank when cold.

I doubt if you hurt anything.

Update: what admiral94 says below is great advice. Keep cap tight.

 

Lo PHAT,

With all the talk about bleeding the coolant system and not having any air in the system, one thing that is forgotten is that pressure is needed to move internal air pockets around, and air is needed to help build that pressure.

Also, overfilling the coolant system will actually prevent trapped air from moving around to the expansion tank.

Water in of itself does not compresses easily, whereas air does. If you study the pressure tank, you will note its design is intended to maintain air in the top of the tank which can provide much needed pressure to help both move air pockets around within the engine (to the tank), as well as prevent spot boiling, which can happen throughout the engine and create pockets of air where there may not have been any to begin with.

If the cap is not being put on immediately, but being left off until the water starts to expand out of the tank, it could delay the pressure build-up and actually cause overheating by allowing the vapor in the block to expand and block the water flow, before the tank pressure builds and counteracts/pushes any air trapped in the block.

I suspect that some of the overheating problems some folks are having is by not putting the cap on immediately to build up pressure and prevent spot boiling in the block/head, along with helping move any 'air' within the system to the logical collection point, the pressure tank.

Regarding your concern about engine damage, not sure about that, but if the thermostat sat in the 260 degree water, there is a chance its life may have been shortened, or its abilility to fully open, reduced.

So, you might consider changing the thermostat, especially if you didn't to begin with.

 

a little FYI for next time. a great tool that helps in doing a coolant fill is a vacuum fill tool. all the manufactures make one(cornwell tools, mac, etc) if you have a compressor and i think they are about 100 bucks for the kit. i have used mine hundreds of times with no air pockets. very easy to use and takes all about 5 minutes to do. years ago i used to fight with cooling systems to get out air pockets but with this tool it makes life so much easier its worth every penny especially if you plan on doing this regularly. just my .02