I purchased a used '93 just recently, and today, I noticed that the temperature gauge is completely bottomed out, even after 15 minutes of running. Luckily, the previous owner provided prior details about the work on the car and in march of this year, the thermostat and temp sender were changed. So, I plan on calling the mechanic on Monday, but is there anything I should know in the meantime? Any guesses on what it could be? Maybe a fuse?

 

I neglected to mention that it seems to have stopped working after the timing belt was replaced. Does anyone know if at any time during the timing belt and water pump replacement service, the temp gauge might be put at risk?

 

Those parts will not affect the guage.
Try hitting the top of the dash and see if the gauge works after it is warmed up. If so the tem. compensation board is bad.

 

I want to add a couple of comments. I'm a car newb, so I have no idea what's related. I know that the mechanics had to drain cooling fluid from the engine to get access to the timing belt. Or something.

I checked the cooling fluid auxiliary holder, and it's waaaaay below the minimum (it was at full). My dad thinks that air might have gotten into the system, causing the gauge not to work?? Thoughts?

 

Disregard my last post I had a brain fart and was thinking it was a 240 not a 850.
The coolant temp sensor might be bad.

 

Even if it just got changed??

 

They just changed it?
If so maybe it is not plugged in good. Follow the upper radiator hose to the motor. Just under it you should see the sensor sticking out the front of the motor. Find the plug and check it.

 

Will do. I'll report back.

 

Sounds like a plan.

 

Take out the sensor and see if they used any type of sealant. Sometimes if they use to much sealant, it will not get a good enough ground on the thermostat housing and will cause the gauge to be stuck all the way down.

 

Nothing's loose. Any thoughts about low fluid levels/air bubbles?

 

Get your coolant level back up to normal and then do just what you said, take it back to the mechanic that changed the thermostat and temp sensor. Probably a very minor problem, but since a mechanic just replaced it, it's his responsibility to make it right.

 

Well the thermostat is not broken. I topped off the coolant and started driving. The needle popped right to the middle, right where it should be. The problem is, I drove it around, parked it for awhile, started driving again, I hit a bump and the gauge immediately dropped to the bottom. It hasn't changed since then. My dad thinks it's a loose wire.

I checked the wiring that's visible from the engine compartment. Nothing's loose in there. Is there other wiring that could be loose? Any other thoughts?

 

I doubt it is in the cluster I have never seen one go bad.

Maybe the wiring in the plug is bad. The rubber falls off of the terminals and then they may not seat all the way.

 

Well we checked the wire from the temperature sensor. It's clean, free of corrosion, and my dad had some sort of gauge that showed that it should send electrical signals.

Do you know where else there could be a loose/bad wire besides the temperature sensor?

 

Btw, thank you so much for the help. You guys have been a life saver.

 

The terminals on the engine side weren't backing out?
Like I said the rubber falls apart and when you plug it is the terminals back out.

 

No. The female piece that goes to god knows where was perfectly intact.

 

OK then maybe the sensor is bad.