1994 Cadillac SLS my car overheats when it wants

TORISMOMMY24

MEMBER
1994 CADILLAC SLS
V8
2WD
AUTOMATIC
145,000 MILES

I have a 94 cadi, sls and it overheats when it wants. It doesnt matter if I am stopped, on the freeway or climbing a mountain. Sometime it overheats really bad and sometimes it overheats a little and then goes back down or sometimes I have no problems at all. I have changed the thermostate twice, water pump, radiator fan, flushed radiator, block/pressure test, all done and it is currently in the shop and they have no idea what is causing it. They even ran it for 4 hours straight and could not get it to overheat. PLEASE HELP! Any ideas?

Saturday, September 26th, 2009 AT 6:32 PM

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Is it actually overheating/boiling over or just the temperature gauge that's indicating it -If so could be the coolant temperature sensor out of calibration-Could also be air lock in the cooling system, try bleeding it

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Saturday, September 26th, 2009 AT 9:42 PM

FACTORYJACK

MECHANIC
4,159 POSTS

If it is in a shop, have them block test it for combustion gases in the cooling system. This can be done with an exhaust gas analyzer. After a good roadtest, place the analyzer at the tank as the radiator cap is removed. Anything over 30 ppm hydrocarbons suggests internal leakage.

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Saturday, September 26th, 2009 AT 11:31 PM

RASMATAZ

MECHANIC
75,992 POSTS

I have changed the thermostate twice, water pump, radiator fan, flushed radiator, block/pressure test, all done and it is currently in the shop and they have no idea what is causing it.

You said they did the block and pressure tests right-Yea the 5 gas analyzer will catch it by sniffing it out of the radiator open this is our way of being a certified emission control I/M specialist-The gas machine does a lot of wonders to include a vacuum gauge-

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Saturday, September 26th, 2009 AT 11:37 PM