6.2 cooling problems

[jtro24]

I have a 93 Chevy with the 6.2 diesel, I installed a new radiator but am having problems with the thermostat working right.When I remove the thermostat everything is fine but when I put it back in my temp gauge goes crazy, up and down constantly. It seems to push a fair amount of coolant to the resovoir but doesn't suck it back thus the in cab heater does not work properly. The book calls for 195 degree thermostat so thats what I am using. The truck starts fantastic and exaust is clear.

[murphyslaw]

dont take this the wrong way but, are you putting the thermostate in the right side up?

[wthif]

Sort of sounds like an air bubble.

[arveetek]

Unfortunately, sounds to me like you might have a blown headgasket. Classic symptoms you have there.

Casey