Thomas Guerra

I'm new here, and did a basic search for overheating issues and may have seen something about a huge air pocket causing similar issues, but looking for you gurus to help.

I have an 09 suburban with almost 200k miles. This past Wednesday, the quick connect at the firewall going to the aux heater core faulted. I pulled over almost immediately, drove maybe 200, 300 feet to a parking lot.
Long story short, I replaced the busted hose, filled with dex 50/50, attempted to burp the system but it constantly boiled over and overheated. Replaced the tstat and tried to re burp system, to the overheating problems.
I got to a point that with front and back heat cranked up it held idle at 210, with fans turning on appropriately. Tested it on with ac at idle for 30 minutes, temp held at 210, no rise or fall of coolant level in tank, no bubbles.
Went to drive it and instantly the temps skyrocketed, so turned around back to my drive.

Most of my research says to check fans or that it's an other worldly size air pocket.

Any thoughts, insights and help on the matter is appreciated.

Thank you, Thomas.

kevinkpk

Replace the radiator fan.

oldchevy

Was it overheating before the heater hose broke? My son's S10 was running real hot all the time. I went to replace the thermostat and saw no coolant where the thermostat went. I filled that up with coolant, put in the new thermostat and no more problems. This could work for you unless it overheated when the hose broke.

Thomas Guerra

Both fans (electric) seem to be working at both speeds, with and with out the ac.

I had no problems with the truck except a cel for fuel evap sensor prior to this hose breaking.

Thomas Guerra

What are the possibilities that the water pump is slipping during driving and not pushing enough water through the system? Being that I can maintain temperature at idle but when I drive the temps spike up.

Doug D

Temperature normal at idle and overheating at speed are symptoms of a scaled up (clogged or partially clogged) radiator. The radiator no longer has the ability to effectively remove the heat. Replace the radiator.

Back when I had a '92 Acclaim it began to run hot (gauge at 3/4) at highway speeds and at idle would be normal. Replaced the radiator and all went back to normal.

KChevy75

There is no burping these. You keep filling the overflow until it fills to a little above the full cold line. Idle the engine for a minute. Loosen the cap then cycle the engine rpms between idle and 3000 every 30s until it reaches 210 and the thermostat opens. Top off to a half inch above full cold.

If it still overheats, you have a blockage somewhere. Try reverse flushing the core and radiator.