Help I have a 2007 Chevy express Van That is over heating and I can’t seem to find the problem. I’ve changed the the transmission, ( I thought it might be from torque converter lock up) I also changed the oil pump ,radiator, water pump, Thermostat, fan clutch and I Bled the coolant system and it still over heats.. When the van is idling it does not over heat .. When I drive it for 20 mins it starts to slowly rise in temp to 260 and I shut it off and let it cool off and drive it for another 20 mins and it over heats.
help!!! I’ve thrown every part I can think of and I’m stumped!!!

 

• Get a head gasket tester kit
• pressure test the cooling system

 

I had a shop pressure test it last month and it held no leak down . That’s why everyone thought it was torque converter lock up or crank case pressure. I changed the 4L80 for a brand new unit and I went through the motor cleaned things and changed new oil pan new melings oil pump and etc

 

I assume you have verified your sensors & gauges are accurate. Does it boil over/look/smell obviously hot when it spikes?

 

Yes it boils over .. Definitely getting hot

 

It could be an incorrect or faulty thermostat, or maybe installed backwards.

 

Try temporarily runnig w/o a thermostat see if problem persists