This is what I have..

2000 cavalier 2.2
Started to overheat Friday.. Both driving and idling..
1. Tested for a bad head gasket (Combustion tester).... no combustion gas in cooling system..
2. Replacement t-stat--- nothing


Last year (running great until this Friday)
New water pump
Flushed heat core (CLR and water)

The hose coming off t-stat stays cold.. So coolant is not flowing..

Questions
Could it be heat sensor?
Clogged heat core? (we have heat)..
Bad reverser cap?

Radiator is newer and fan kicks on..

Thanks,
Bug

 

Welcome to the forum
I might have thought possible bad sensor, but when you say that the radiator hose is cold, that tells me you have a flow issue... that is T-stat or water pump...even new t-stats and water pumps go bad....

 

Air in cooling system?

Water pump?

 

If I take out t-stat and it runs fine.. Than bad t-stat.. If not then bad water pump..
We have all air out of cooling system.. Nice flow of coolant..

 

It's not hard or expensive to bypass the heater core. That will help point to the problem area. Use a new hose to go from the small metal tube (under the larger tube top front that goes to the top of the radiator) to the thermostat housing. If all goes well then you still have a restricted heater core problem. I BACK flushed my heater core using CLR and have had no problems since (knock on wood

 

We did a clr flush this past summer..

 

The whole system or the heater core? I flushed mine in reverse flow and got a bunch of "kitty litter" looking junk out of the heater core alone. Still try and bypass the heater core to either eliminate or confirm the heater core as a "LOW" flow caused mine to overheat. The heat still worked great even with the low flow. At stop lights it would get hot, drive it like an old man it got hot, drive hard and fast it ran cooler, if i kept the rpm's up it ran cooler, It needed more "FLOW" than i was getting threw the heater core. Please try and do the bypass.

 

Flushed it out.. I didnt see anything come out of the core, block or radiator.. I am changing the water pump now.. Please update you in a few.. Thanks...

 

You didn't mention if everything was okay when driving or just when stopped?

Is your radiator fan working?

 

Any updates? Inquiring minds want to know.