The tstat rose again, but came back down pretty quick. Air was blowing hot, and the cooling fans worked. The events seem to be bubbles, I was driving on gravel roads a bit before this most recent event, so maybe that stirred some loose? Should i take the car back in and make them bleed the coolant system?

 

i agree with above. you have a air bubble in the system. Usually with a bad HG you have poor or no heat, and the temp gauge would climb higher then your seeing.

 

nipper

Just in case anybody is experiencing similar problems, I did end up having the head gaskets replaced. I never overheated the engine, but there was definitely exhaust making its way into the coolant, forming a bubble at the tstat, then passing.

 

I took the car to superior import repair, and a hydrocarbon test showed HCs in the cooling system.

 

It was what I expected in the end. On a brighter note, since the heads were off, I had the valves cleaned, and have not had the shuddering or cylinder 4 misfire code since.

 

I don't know if the valve cleaning or the TransX additive are what took away the shudder, but I'm hoping it was the valve cleaning. Only time will tell.