Hi,

I'm Mark in NC with a '92 Suburban C1500, looking for help diagnosing an overheating/ running hot issue.

The truck overheated a couple of weeks ago and when I pulled over there was a small leak in the radiator.

I replaced the radiator and also the two temp sensors and the thermostat.

The dashboard gauge goes up to max within about 10 minutes of driving it.

I haven't replaced the water pump, but the heat in the cabin works and it looks like coolant is circulating when I run it with the radiator cap off.

The upper radiator hose gets very hot, but the coolant is not boiling and going into the overflow reservoir when I drive it, so I'm not 100% sure it's overheating, but the dash gauge seems to work. It'll gradually go up in temp if I just idle it in the driveway.

Is there something I'm missing here? Any ideas on what to check next?

 

Can you feel fluid movement from the upper hose when the engine is up to temp?

 

Hi @kevinkpk , I'm running it now to warm it up, we'll see in a few minutes. Do you think the thermostat is not opening?

 

I know you posted you replaced it, but yes, find out if it is opening.

 

@kevinkpkNo, it feels empty, the upper hose. Not firm and full of liquid.

 

Is the thermostat installed correctly? With it open, you should be able to feel flow. I'd not recommend running it without a thermostat, but you might remove it, see if you overheating problem is solved. New dosen't mean good.

 

Hey @kevinkpk,

Thanks for helping me with this! Yes, it's installed correctly. I'll try running it without and see what happens. If it doesn't overheat, then the new thermostat is no good, correct?

 

I'd suggest replacing it with a 160 deg. stat.

 

you can put the stat in a pan of hot water on the stove with a thermometer; see at what temperture it opens up. Wondering if you still have air in the system

 

Road test without the stat- it did not max out the temp gauge, but it stayed at around 225. This is an improvement, but still hot.

Amazing that a brand new part was bad.

I still don’t feel fluid running through the upper hose. Maybe the water pump is bad?

I burped it by parking it on an incline and running it with the radiator cap off.

Thanks again for the help!