Coolant resovoir bubbling and spewing out!! what do i do
 

when i stop after a 10 minute or so drive, i can hear the coolant bubbling in the tank and then it spews out in pulses. but the DIC doesn't display any overheating warnings.

any ideas as to what is going on??

-i know my resovoir sensor is bad, so i have to buy a new tank (but could this be the cause)

-i checked between the radiatior and condensor and its free of any obstructions.

i was told that it is vapor lock and to disconnect the coolant lines off the back of the heads and to fill the system until it comes out of the lines, then reconnect.

what do i do. this is driving me crazy.

cap may be bad..

the overflow cap or actual radiator cap?

i didn't know that could cause such a problem.

Just to be sure, check you oil for water. (milkshake) A headgasket leak could allow combustion gasses into the coolant system, over pressurizing it. Hope it's not that, but check to be sure. :cheers:

I kept having that problem with my '97 vette as well. I took it to the stealership for a service and thought they fixed it. 2 weeks later it TOTALLY overheated and I got the dreaded "Reduced Power" warning on the DIC, I got it towed to the stealership only to be told that the heads had warped due to the high temps from the overheating :cuss I was told that it would cost in the region of $2,000 and up to fix. :nono: I'm not that mechanically minded, so don't know if that really was the problem???

The diagnosis from the stealership was that the thermostat was stuck open!

I'd replace the thermostat (pretty cheap to do) and see if that makes any difference. If not, I would take it to a trusted mechanic. :yesnod:

Any gearheads out there please tell me if I could be wrong! Don't want to scare you but don't want you to end up in the same position as I was in. Hope this helps.

:cheers:

now im getting worried. i have had bad luck at the dealer and already have had it in there once for this problem with no fix.
(they told me i had grass in my radiator, which was complete bs, because when i went to pick it up it changed to a bag in the radiator)

Thermostat stuck closed causes overheating, but stuck open cannot. If it's stuck open, the car will not warm up very fast and on very cold days, it may never warm up at all. But when the engine is hot, guess where the thermostat is supposed to be? Wide open. So stuck open could not cause overheating.

Does it bubble during warmup before the car reaches operating temperature? Leave off the cap and start the car. If so, chances are you have a blown head gasket or worse, warped heads.

Advice to check oil dip stick, looking for milky white was good. This would show water in oil, which would also confirm blown head gasket or worse.

What are your tempersatures running? With a bad radiator cap, you should not be able to get over about 212, and water would boil.

The dirty radiator can be between your air conditioner condenser (this is what you see when looking up your air intake) and radiator, which you can't see from either side. Take off the top "cover" and look in there, you can clean out with low pressure air or water.

Good luck.

OK people......lets go with the easy cheap stuff first.
1. Check radiator for debris blocking the airflow and clean if needed.
2. Check or just replace the coolant pressure cap (most likely the problem)
3. Check the actual temp driving down the road if #2 doesnt fix it, it may be either stuck thermostat, bad fans or relays, clogged radiator, and last but not least head gasket problems.

By the way, on some cars a stuck open thermostat can lead to overheating. The coolant goes through the radiator so fast that it does not have time to cool down and goes back into the engine hot.

:iagree: :thumbs:

:iagree: :iagree:

well i just went outside, started the car and let it idle. At about 225 the coolant comes out of the resovoir. So it idled for about 8 minutes before it actually spewed out.

----My oil looks normal. no white/milky color
----No debris in radiator or condensor

Its crazy because my car did this about 7 months ago, then it stopped. And now its starting all over again.

How would i know if its the thermostat? Is this an easy swap?

Could it possibly be my bad sensor in the resovoir tank?

Oh, and what temp do the fans come on??

I would replace the thermostat - it's pretty easy to do. At 225 degrees, your fans should have come on - I'd look into that also.

im gonna go buy a new cap ($8 ) first and order the t-stat.

Does anyone think my bad coolant sensor could cause this problem?

What about vapor lock? air in the system?

This may be a stupid question but....does it have anti-freeze in the water or is it just pure water???

dex cool plus water.


could water only cause it to overheat? I though anti freeze was to prevent freezing.

maybe i have an off ratio

If you are talking about the coolant level sensor on the resevior, no it cannot cause this problem. And Vapor lock is a term for fuel boiling in the lines, it too has nothing to do with this. Air in the system, yes, can cause an overflowing resevoir and over heat the engine, but it doesn't just happen all of a sudden and unlike the C4, the C5 does not seem to have an airlocking problem. After working on the coolant system, you just fill it up and it does a good job of clearing the air by itself. Do your fans come on? Turn on the AC while the car is sitting still. The fans should come on imidiately. And if they are not working, the AC will not work very good sitting still. Glad to hear it is not a head gasket.

im glad to hear its not a head gasket as well. I hope its an easy fix.

Can the cap being bad possibly be the cause? The car did make it up to 226 degrees before i shut it down.

Any links to a thermostat install? I actually had my whole engine replaced a few years ago inlcuding water pump etc. is it possible for the t-stat to go bad.

I have to dissagree. Maybe removing the thermostat could cause too much flow. But think about it, the thermostat cannot get stuck open farther than it is supposed to be open when the coolant is hot. Right? So when it is functioning properly, it is wide open at say 210 degrees and up. Therefor it will be flowing the same amount of coolant if it is stuck or working correctly. It will only flow less when functioning correctly when the coolant is cooler. And by definition, when the coolant is cooler, it is not overheating!! Please try to explian how I am wrong. :bigears

No way the coolant sensor would cause the car to boil the coolant out. Thermostat, plugged radiator, fans not working, or blown head gasket probably the culprit.