my 95 SSE lately has had some strange symptoms. the temp. gauge will suddenly spike up to the red, and as soon as it gets there will fall rapidly back down to normal temps... what are the usual causes of this? someone i know said that his car had the same thing and it was a bad head gasket...
did my LIM or UIM finally go?
should i be driving it?

:?

First thing to do, check your coolant level.

Low coolant will cause your temp guage to jump around like that when the sensor is in the air pocket then water hits it.

As I am sure you already know, it is EXTREMLY unlikely for a head gasket to go on a 3800. Chances are it would be your LIM gaskets going bad.

also, check your oil right now!!! make sure there is no milky look to it. If there is, change it as soon as possible, then stop driving it untill you get your gaskets changed.

Clean your battery cables at both ends before trying anything else. [/b]

the coolant is fine, oil looks fine on dipstick and looked fine on the last change.. its at about 2000 miles right now i tihnk. the battery is relatively new but i will check the connections.

bump?

any other possible causes? i need to get some opinions before i go tearing my engine apart...

Pull the boots OFF the battery ends of the cables. Tell us what you find.

When was the last time the thermostat was changed out? Maybe it is sticking and only opens once the temps are really high bringing your temps back down to normal.

Alot depends on how fast 'suddenly spiked' is. Less than a second? A minute? Give us more info.

that was my first thought too. just replaced it. i boiled the old one in water, and it opens fine too

somewhere between the two.. i would say from 200 - 260 or so it takes about 30 seconds. maybe a bit less. i will check the battery cables later today.

ok, i guess this thread isnt too old to start again. my bad

well today i started up the 97 and the 95 side by side, and used an infared temp gauge to check the thermostat housing, engine block, etc. and found out that although the gauge on the 95 reads 60* hotter, the engine is roughly the same temperature! Very Happy i'm glad the engine is not running that hot.. I did notice some possible corrosion on the radiator by the hose that comes out near the airbox. could a bad radiator somehow affect the gauge?

the only problem is, i have replaced the temp. sensor so i don't know why i am getting these bad readings, or why it is only some of the time... sometimes the gauge appears to read normal. this is why i thought the engine was actually getting hot. i figured that if the gauge was bad, it would just stop working or constantly read high, not fluctuate. today it read steadily high though.



another problem (possibly related) is that my fans dont come on. is this a fuse or relay that could be bad, and causing the gauge to read funny as well as disable the fans?

EDIT: is there another possible way to read the temp, that wouldn't also give me false readings? maybe an aftermarket temp gauge? (the dash one may be bad) and i dont feel comforatable not having a working temp gauge indefinitely. is it possible to read the temp with an OBD-I car?