00 Alero 3.4, overheats even after LIM

[ericcfx1984]

I have bleed the system

it can idle and put out good heat, even let it idle for well over an hour... no issues, it stays right at the middle of the temp gauge

after driving for around 2 miles the heater gets cold, then the temp gauge rises to around 3/4 or so

after that I pull over with the car still running and crack the bleeder and a bunch of air comes out...

then the car cools down again and is fine, but the heater is not, I top off the reservoir again and the heater comes back.

I went thru this 3 or 4 times


finally I tired a pressure test at idle... it does not make much pressure, maybe a little over 5 or 10, but if you rev the engine the pressure drops to the point where it sucks the coolant back down... (negative pressure? suction?)

I have to get this figured out...

the oil is clear, not at all milky, in fact it looks new

[ericcfx1984]

ok I ran a head gasket test..., you know the tube that you put into the overflow reservoir and you put the blue fluid in the tube, then put the rubber bulb on top, start the car and pump it...

if the fluid turns yellow or even brown then you have exhaust exhaust gases in your coolant...

the fluid stayed blue, so NO head gasket leak...



the coolant is NOT coming out the tail pipe



then I tried a radiator pressure test, got the pressure up to about 10 psi before I noticed a very small leak in drivers side(left) radiator hose, near the thermostat...

I fixed that leak and topped it off...

but it still over heats...

[aleekat]

Stuck thermostadt/faulty water pump?

[ericcfx1984]

Originally Posted by aleekat

Stuck thermostadt?

it does open up, I could pull it and try it in a pot of water...

[inafogg]

have you checked the radiator cap??

[ericcfx1984]

Originally Posted by inafogg

have you checked the radiator cap??

ummm.. no... what should I be looking for?

[BNaylor]

Have you tried a compression test to check for a head gasket issue? It sounds like you are getting pressure from someplace since there appears to a alot of air in the cooling system.

On the radiator cap there is none. The cap rated at 15 psi is at the coolant reservoir and the setup is different compared to other GM cars that actually have a radiator cap on the radiator. Doesn't hurt to check it though.

[ericcfx1984]

Originally Posted by BNaylor

Have you tried a compression test to check for a head gasket issue? It sounds like you are getting pressure from someplace since there appears to a alot of air in the cooling system.

On the radiator cap there is none. The cap rated at 15 psi is at the coolant reservoir and the setup is different compared to other GM cars that actually have a radiator cap on the radiator. Doesn't hurt to check it though.

no I have not tried a compression test yet

so you are saying that there is NO pressure in the cooling system?

the reservoir cap seems fine

also I took out the thermostat and checked it it a pot of water, it opened at 195F

[ericcfx1984]

I have been running this test with water... no coolant... my tests show that the thermostat opens at 195F, which is VERY close to water's boiling point

and I have heard that the fans do not kick on until around 220F

what if the water is boiling 212F, meaning that there could be a point in the block where the water is boiling and becomes vapor... this might explain the 'air pockets' coming out of the bleeder when the car overheats...

[tblake]

You may be on to something, and it might be a good idea to have coolant in there anyways.

[tblake]

Did your car overheat before you changed the LIM gaskets? Or I suppose you didn't run it long enough.

Stupid question, and I don't mean to insult your intelligence because you did just replace your LIM gaskets, but is your t-stat installed in the correct direction? Spring side facing the motor.

[ericcfx1984]

Originally Posted by tblake

Did your car overheat before you changed the LIM gaskets? Or I suppose you didn't run it long enough.

Stupid question, and I don't mean to insult your intelligence because you did just replace your LIM gaskets, but is your t-stat installed in the correct direction? Spring side facing the motor.

yes it did over heat... but it was pumping coolant into the oil at an alarming rate

but i purchased the car like that

What? What? What?!!! How dare you!!! LOL... Just kidding.... but yes it is going the correct way... as far as I know it is too long to fit the wrong way
(at last with the cross over exhaust pipe installed)

[tblake]

Originally Posted by ericcfx1984

What? What? What?!!! How dare you!!! LOL... Just kidding.... but yes it is going the correct way... as far as I know it is too long to fit the wrong way
(at last with the cross over exhaust pipe installed)

Well, someone over on a different forum replaced his head gaskets and was having issues like you describe. I asked him if he was sure the stat was in the right way and he flew off the handle about how if he knows how to replace head gaskets then he definatly knows how to put a thermostat in. A week or so later he updated everyone that he needed to replace the head gaskets again and that solved his issues. So apparently he had now clue how to install new head gaskets.

[tblake]

I hate to say it, but had I known you bought it this way and it didn't just start peeing coolant into the oil, I'd have probably went down to the head gaskets right off the bat. As the original owner may have over heated it to the point of bag head gaskets. And since the block is cast and the heads are aluminum, you might want to bring the heads in to get check for warps and machined as necessary.

[ericcfx1984]

Originally Posted by tblake

Well, someone over on a different forum replaced his head gaskets and was having issues like you describe. I asked him if he was sure the stat was in the right way and he flew off the handle about how if he knows how to replace head gaskets then he definatly knows how to put a thermostat in. A week or so later he updated everyone that he needed to replace the head gaskets again and that solved his issues. So apparently he had now clue how to install new head gaskets.

wow... that would suck...

either way I already did the headgasket/block test (3 times) and it passed...


this is the type of test I ran

http://www.arrowheadradiator.com/hea..._leak_test.htm



also did a radiator pressure test and was able to build and hold pressure no problem