I am having an overheat problem on my sons 1996 SL2
It has:
1) New coolant overflow tank
2) New radiator
3) New upper and lower rad hoses.
4) New coolant temp sending unit and new cap on it.

It runs fine heat gauge never goes to half way when engine is totally hot, however when you stop all the fuild in the overflow tank boils out.

Any suggestions?

 

Check and make sure that the radiator cooling fan runs. Connect wire directly from the battery, and verify the fan works. Put the wiring back to normal,then start the car and turn the A/C to maximum, the fan should start and run. Final check would be to check the car when it's stopped, and the temp gage is above the 3/4 point.

Do all these tests, and let us know what you find .....

 

are both the upper and lower rad hoses hot?

 

Fan runs fine in all positions. However ran into a new problem turns out the round seals in the valve gasket which go around the spark plugs are leakin so the oil is pooling around the spark plugs (so much so that it almost covered the top of the plugs). So I need a valve gasket first.
I have been told I should buy a tester from Autozone around $20.00 to determine if exhaust gases are entering the coolant. It is a blue fluid that turns yellow if exhaust gases are entering the coolant. If this happens then the fluid overheats and boils out the coolant tank. If this is the problem then I need a new head gasket. When this happens I am told most times coolant does not enter the crankcase.
So first thing - vacation 2 weeks starting tomorrow.
Second - valve gasket install, check upper and lower hoses- report back here.
Third - test coolant to exhaust gases - report back here.
Forth - check head for problems if none install new head gasket - report back here.
Thanks for all the input I will keep everyone posted, love the forum.

 

I asked if both rad hoses were hot b/c if your water pump ain't pumping, your coolant ain't circulatin', your coolant temp reading will be bogus, thus not telling the PCM when to properly engage the cooling fan, etc.

Forgot to mention that the overflow tanks have been known to warp. But if yours was not sealing properly due to that I don't think it would wait to overheat until the car stopped moving.

Also, I wouldn't rush into a head gasket before you are SURE the head is not cracked.