geo still overheats

[thenn3025]

Car still overheats. Put in new head bolts and gasket. No change. Still get air bubbles in the system. Don't know where they are coming from. Radiator has been flushed and cleaned. Took water pump off and inspected it's ok, only 2 years old. Water circulates ok. I am at a loss as to what to do. Everything has been changed but the block and I am not going that far.

[geozukigti]

If you leave the radiator cap open, will coolant flow out of the top?

[thenn3025]

Originally Posted by geozukigti

If you leave the radiator cap open, will coolant flow out of the top?

That would be a no. When I have the cap off and the water a little low I can see it flowing across the cores. The water will rise a little, but that must be from the air that is somehow getting into the system.

[geozukigti]

Well, this is kinda messy, but try this out. Drain the coolant(you'll have to). Take both the upper line and the lower line off the radiator. Then pour a bucket of water in the radiator cap. Make sure the water flows out the bottom of the radiator as quickly as you can pour it in. If it starts to overflow out of the upper hose line, you may have a clogged radiator. Did you have the head pressure checked before it was installed? Also, do you notice any milky residue in the valve cover after the engine starts to overheat?

[thenn3025]

Originally Posted by geozukigti

Well, this is kinda messy, but try this out. Drain the coolant(you'll have to). Take both the upper line and the lower line off the radiator. Then pour a bucket of water in the radiator cap. Make sure the water flows out the bottom of the radiator as quickly as you can pour it in. If it starts to overflow out of the upper hose line, you may have a clogged radiator. Did you have the head pressure checked before it was installed? Also, do you notice any milky residue in the valve cover after the engine starts to overheat?

Have done the radiator thing. Had it out,ran water every which way through it. Seems to flow through it ok. Did not have the head checked. As this is it's second head and it does the exact same thing I did not think it was that. Although it could be. No water is getting into the oil that is still clear. I have no air bubbles in water until the engine gets up to operating temp. As the engine get hotter the bubbles get worse.

[geozukigti]

Will it get up to normal operating temperature before it starts to bubble? Or does it bubble before normal operating temp?

[thenn3025]

About the time the temp gauge gets to the middle and the hose is getting warm then the bubbles start. If you rev the engine up you get a steady stream of small bubbles. When you let it go back to idle you get a bunch of larger bubbles for awhile. That is when it likes to blow the water out of radiator(with the cap off).

[geozukigti]

Yeah, you have a compression leak somewhere. Either the head is cracked, head is warped, block is cracked, or one of the 2 gasket surfaces are not flat, and won't seal. I know you don't want to do it again, but if you pull the head, get some copper gasket spray. Clean the gasket off really good, then spary it with a layer of the copper spray. Let it sit for a few minutes, and then put it on. Also, make sure both gasket surfaces have absolutely nothing, not even dust on them. One even slight scratch, and you can get a compression leak. I had an 88 Dynasty do this same thing to me before. It ended up that the heads were warped, and had to be milled .020". It got me a little extra compression while it was at it too.

[thenn3025]

I have done the copper spray before. Didn't make much difference, but I can try it again. I am getting really good at taking the head off. Have done it about 15 times. I can have it off and laying on the bench in about 30 minutes. 20 if I really hurry. Thanks

[biglistofmods]

i had the same prob with my car.
it would look like it was flowing nice and the temp would climb quick and if i took off the cap it would bubble all day.
wound up being a radiator. i would try a rad and some new panti freeze