Mark_Cool

Hey Y'all,

I've got a 92 Suburban C1500, 2wd, 5.7. I'm looking for help diagnosing an issue with the dashboard temp gauge/ cooling system.

The truck overheated a few days ago while driving on the highway. The temp gauge stopped working after that, stuck on 0.

I replaced the temp sensor located behind the #1 spark plug on the engine block. The temp gauge went up to max after a brief test drive.

I replaced the thermostat just in case. Still the same- temp gauge goes to max after idling for a few minutes. The engine doesn't seem hot.

I burped the system with the truck on a slope and the radiator cap off. The temp gauge maxed out, the radiator did not boil over.

It looks like the water pump is working- with thew radiator cap off, water is being pulled downward while the truck is running. The heater works inside the cab when the truck is running.

Any suggestions as to where to go next?

Thanks, I appreciate it!

Mark C in Efland, NC

oldchevy

Welcome from Florida. You might have the incorrect sending unit or a bad one even if it is new. The gauge could be bad or the wiring could have been damaged when it overheated. You can also check the engine temp with a mechanical gauge to verify the exact temp.

Mark_Cool

Thanks Oldchevy!

I'm actually not new to this forum, but it was easier to start a new account than to try to track down my old login info.

Mechanical gauge- is that available at an auto parts store?

The gauge didn't work at all, then it started going to HOT after I replaced the block sensor. So I think that sensor works.

Mark_Cool

I also replaced the ECT that's next to the thermostat housing, and I drilled a hole in the thermostat just in case?

Temp gauge still maxing out, even though I'm not sure if the engine is actually overheating.

Mark_Cool

I even replaced the radiator- still no dice, still showing HOT on dashboard gauge after running a few minutes. Is there some sort of system reset to do after replacing the sensors?

oldchevy

You can get mechanical water temp gauges at places like Ebay, Amazon and Autozone for good prices.

Birdman01

Did you find out why the truck overheated? Was it the radiator? Like Oldchevy said, for testing purposes you can get a mechanical temperature gage at any local auto parts store like autozone or O'reilleys and even on Amazon.com and Ebay. Another option is to get a Temperature Digital laser gun and point it to the thermostat housing or the radiator hoses to find out if the engine is really running hot or not. Also,remove the one wire that connects to the temeperature gage sender ( the one next to the 1 and 3 spark plugs) and than turn the key to the on position and see if the needle on the gage drops to 0. If the gage still shows Hot ,than I would say that the gage is bad. If thats the case,I would just leave the mechanical gage installed.