2007 H3 120k miles. New thermostat, dual core aluminum radiator, head gasket, plugs, trans flash and it’s been in the shop 4 times for overheating ..as in need to stop as smoke billows from under hood. Cabin Heater didn’t work but that was solved with new radiator. Now the overheating seems to happen at idle and goes back down towards normal when driving. Any thots?

 

How long have you owned this H3?

Almost sounds like a prior owner tried a bunch of coolant stop leak stuff and clogged something besides a possible leaking radiator?

 

Bought it new off showroom floor. Regular mx always done. This all started w a o2 sensor code which as we know can be many diff things. No one could figure it out but it was finally resolved when the head gasket was replaced. Now the overheating is a mystery. Radiator was last thing to be replaced as mechanic found crack last week. It ran better and took longer to overheat but still overheating. Prior to replacing radiator, overflow was full of thick mud like liquid.

 

^^^I'd start with that and would suspect that the new gasket was not installed properly and some cooling passage is now blocked.

 

x2 ^^

 

I guess it is possible to put the head gasket on wrong but you would really have to be trying to get it wrong. or completely oblivious to common sense.

 

X3=The Head Gasket was not repaired properly.
Buy a Head Gasket Tester, they are cheap on Ebay

 

^^^ That. Here you can see what the gasket looks like (overlaid on original) when put on upside down. Most everything still lines up the same except a couple of areas that a ham-fisted/oblivious mechanic could "make fit" if they tried hard enough.

 

 

i had an issue similar with a ford years ago. at idle it would run hot but driving it ran fine. it wound up being my water pump. it had somehow lost the impeller blades. only the backing plate was left and it looked like a circular saw blade. i guess there was still enough motion to move some coolant at higher rpms but not enough for idling.