Little help with temp gauge

Kevo · Nov 20, 2014

I got a '94GT that is basically a toy. I drive it on purdy days and that is about it. Well this weekend was going to do a little Christmas shopping with the wife and the car died at an intersection. Turned out to be the alternator wasn't charging so got that changed and a jump and went along our way. The next day I drove the car around a little more to get the battery back fully charged and noticed it started to run HOT (by the gauge and by HOT I mean a little past L in NORMAL). I babied it back home and checked the cooling system. Fan...good, Coolant level...good, Thermostat...good (felt upper hose and was hot and tight so new it opened). I called my friend over with his IR thermometer and hit the motor in a few places...the gauge was reading a little past the L and the engine was only 185*. Now I'm thinking wiring issue and more into a bad ground. I cleaned the grounds in front of the driver side headlight and engine block with no resolution to the issue...any other places for grounds I should look or anyone possibly ran into this issue before?

Thanks,
Kevo

mcglsr2 · Nov 20, 2014

Depending on age, your coolant temp sensor is probably bad. If you aren't sure where it is, it's located here: looking at the engine, driver side on your right, it's at the front of the intake, right side, kind of tucked behind the dizzy. It's mounted in a vertical position. This sensor tells the gauge in the car the temp - NOT the ECU. The ECU actually uses a different sensor.

If you are interested, I recommend getting an Auto Meter water temp gauge, mount it in your favorite place, and use the sensor that came with the gauge in place of the stock one. Now you'll know the exact temp, rather than reading a O, or M or L. Because the sensor is for gauge only, it won't interfere with the workings of your ECU - it just means the gauge in your cluster won't work anymore (which is fine, they are notoriously inaccurate).

If you decide to do this, and then the Auto Meter gauge shows really hi temps, then you know something else is going on.

ttocs · Nov 21, 2014

The stock temp/oil pressure gauges are basically useless. I saw first hand how on the dyno how the car was overheating and pulling timing out according to my tuner to try and cool it, and the gauge never got more then half way. The oil pressure shows pressure as long as there is something stupid like 6 lbs.

Kevo · Nov 24, 2014

I looked over the car good this weekend and found a terrible looking ground from the chassis to the motor. I replaced ($6) and all my issues were resolved at once. Thanks for the help everyone.