The factory guage on my 88 doesn't seem to be working right, or I could be wrong. When it warms up, the needle doesn't even get to the halfway point, so it looks like the engine is running super cool, but I find that hard to believe. The kid I got the car from also said if the needle is ever in the middle then its overheating.... really? My question.. how would I go about checking this, and where the hell is the temp sensor?

Thanks in advance!

 

On an S4, which you have, the needle should peg out at 1/3 the way up at most and at least 1/4th off the bottom when the engine is at operating temperature.

 

The factory temp gauge is crap anyways, and shouldn't be trusted if only used as a reference. After the years who know what has happened to that needle, the gauge, or the sensor.

Get an aftermarket coolant gauge if you want to feel better about it.

To answer your question though the sender is attached to the driver side of the rear iron. It's a tiny little guy that screws in below the oil filter pedastal.

 

Awesome! Thanks guys