Engine gauge won't warm up

[mephiska]

I've searched this forum and tried both remedies suggested for an engine temp gauge that won't get to normal levels.

Problem: Temp gauge never gets up to full operating temp, at least on other cars I've owned. The highest I've seen it is 1/5th of the way between the C and H. And it fluctuates fairly frequently and quickly, usually hovering right above the C position.

Things I've tried: I've replaced the thermostat and the temp sending unit. Neither seemed to have any effect.

The heater works works just fine.

 

[Jakespeeds]

I would like to see this worked out also. My 94 has the same problem. But I just over the weekend found a factory bulletin about faulty reading temp senders that were recalled for me year. I was going to swap out the temp sender with a new unit to see if that fixed mine. Did you get your sender from the dealer or a local autoparts store?

Jake

 

[mephiska]

Kragen, not an OEM sender. This is the one with one wire going out of it, which as I understand it is the one that sends the reading to the gauge.

 

[locovaca]

Disconnect the wire from the sender and ground it. The gauge should peg all the way hot. If that works then it eliminates a lot of possibilities.

 

[Earl43P]

Cover 1/2 of the front of the radiator with a piece of cardboard.

Drive a few miles, observe temp.

If it climbs up into the more normal range with that blockage, replace the fan clutch.

 

[mephiska]

Excellent, thank you for the suggestions!

I drove over 100 miles in it yesterday, lots of freeway driving. It never did really heat up very much. After the drive I felt the hood and it was cool. I put my hand near the radiator and it was still pretty darn cool. I'll try the cardboard first I think.

 

[Rearanger]

If you can get access to an infrared thermometer then aim it at the upper rad hose just down stream of the thermostat after you've run the engine and see what the actual coolant temp is. Hard to believe a new thermostat was also defective, but possible. If you've done the gauge check then only other thing I can think of is trapped air where the temp sender is installed and coolant is not actually flowing over the sender probe.

 

[mephiska]

I'm thinking it may be the fan clutch right now. Is it normal for the fan to be on all the time? It looks like its driven right off the crank, mine spins full time, never stops. Is that normal?

 

[cush]

no. you'll hear it if the fan spins all the time. go watch a youtube video. it sounds like a giant vacuum. but if your fan is on all the time then replace the fan clutch.

 

[locovaca]

I'm thinking it may be the fan clutch right now. Is it normal for the fan to be on all the time? It looks like its driven right off the crank, mine spins full time, never stops. Is that normal?

Take a cardboard tube or fairly decent piece of cardboard, start the engine, and try to stop the fan blade with it. If the clutch is working you should be able to stop it with the cardboard. The clutch will always spin the fan even when not engaged but it shouldn't take very much to stop it.

 

[cush]

Take a cardboard tube or fairly decent piece of cardboard, start the engine, and try to stop the fan blade with it. If the clutch is working you should be able to stop it with the cardboard. The clutch will always spin the fan even when not engaged but it shouldn't take very much to stop it.

i wouldnt recommend sticking anything in the fan. i mean, it seems like a good test but is dangerous.

 

[locovaca]

i wouldnt recommend sticking anything in the fan. i mean, it seems like a good test but is dangerous.

http://www.ehow.com/how_5865385_test-fan-clutch-chevrolet.html

http://www.ehow.com/how_5939566_troubleshoot-fan-clutch-ford-explorer.html

http://www.exploroz.com/Forum/Topic/40778/Viscous_Fan_Coupling_-_How_To_Test.aspx

http://forums.bimmerforums.com/forum/showpost.php?p=1300422&postcount=5

Obviously you should be wearing safety glasses when doing the test...

 

[Rearanger]

Even if the fan is struck always-on that should not prevent the thermostat from maintaining the proper engine temperature.

 

[TomB1269]

Coolant level will cause low reading and the fluctations. The upper hose is higher than the radiator cap. You have to bleed the air out of the system by letting it run with cap off until the T-stat opens and fluid starts to run.

 

[Jason]

A constant fan can cool a radiator faster than the engine can generate heat.

Simple test. Start the truck in the morning, or when you know it's cold with the hood open. If the fan spins faster than your eyes can track the blades, the clutch is locked up and needs to be replaced.