Stumped

[Greenman]

My daughter has a 96 Buick Regal that has me baffled. It overheats for no reason that I can see. There is no evidence of a blown head gasket, it has a new thermostat, new radiator, and the water pump is working. The electric fan comes on at 105C, where it's supposed to turn on, but thats just a tad under overheating according to the temperature gauge. Because of the high temperature, it won't pass smog. It also has a new temperature sender that reads exactly the same as the old one. There is 104k on the clock. Other than overheating, the car is in very good shape.

I don't know what to do at this point. The next step appears to be junking it and picking her up another beater.

Any ideas?

Edit: The engine doesn't actually overheat, it just runs very hot.

 

[Doomer]

Reminds of an old car I once had that overheated for no apparent reason. It took a long time to find but the cause was a cracked distributor cap. I have no idea how it made it overheat but I do know that once I replaced it it never even got warm until I put the thermostat back in it and then it never got past half way on the gauge even when in stop and go traffic in the heat of the summer.

 

[Zenmervolt]

Have you replaced the radiator cap? If the cap isn't holding full pressure the car can run hot even if everything else is working properly.

ZV

 

[Greenman]

Have you replaced the radiator cap? If the cap isn't holding full pressure the car can run hot even if everything else is working properly.

ZV

New cap with the new radiator.

I'm starting to think that it has something to do with with the dexcool turning to sludge. It may be time to call the junk yard.

 

[MongGrel]

Sounds stupid, but have you flushed the whole cooling system to begin with ?

 

[Greenman]

Sounds stupid, but have you flushed the whole cooling system to begin with ?

Yup, did that today. Because of the location of the drain valve, I managed to scald the shit out of my hand. You'd think after working on cars for over 40 years I'd know better, but you'd be wrong.

 

[LTC8K6]

Is the WP flowing enough coolant? It may be pumping, but pumping poorly.

 

[LTC8K6]

105c is 221f - that sounds high for the rad fan to come on.

Looking around, it seems like that's actually normal for GM.

 

[Greenman]

Is the WP flowing enough coolant? It may be pumping, but pumping poorly.

It seems to flow well. I pulled the thermostat housing and started the engine, and there was a hurricane of coolant gushed out. I know thats not a real scientific test, but it does prove the pump is working.

 

[Greenman]

A brief PSA is appropriate at this point. BurnJel is a God send for stupid people. So, if you work on cars, and you're not bright enough to keep your hands out of the boiling coolant, get a jug of this stuff, you'll thank me later.

 

[silicon]

My daughter has a 96 Buick Regal that has me baffled. It overheats for no reason that I can see. There is no evidence of a blown head gasket, it has a new thermostat, new radiator, and the water pump is working. The electric fan comes on at 105C, where it's supposed to turn on, but thats just a tad under overheating according to the temperature gauge. Because of the high temperature, it won't pass smog. It also has a new temperature sender that reads exactly the same as the old one. There is 104k on the clock. Other than overheating, the car is in very good shape.

I don't know what to do at this point. The next step appears to be junking it and picking her up another beater.

Any ideas?

Edit: The engine doesn't actually overheat, it just runs very hot.

a partially blocked catalytic convertor can cause this problem.

 

[BUTCH1]

Is the WP flowing enough coolant? It may be pumping, but pumping poorly.

Good point, over that amount of time the vanes might be corroded to the point where they will push water easily like when OP had the thermostat opened for replacement but when faced with forcing the coolant through the block and radiator it may not be able to generate enough pressure to do so..