My 2000 mc 3.4l has a conveniently located thermostat.......lol. The new one I just put in leaks a little. Advanced Auto thermostat with seal included was installed.... whats the right way to get these in without leaking.....Should I buy a "higher grade" seal or use a thin film of sealant to hold it in? I really want this fix to work the second time around....Ideas please!!!! Thankyou.

 

Same problem. I just replaced all the gastkets in my manifold. Boy am i glad that is over. It was tough, but rewarding (changing the heater core the other day was actually worse). I just put a bead of RTV around the thermostat tonight. Ill let it sit overnight to cure. I think that should do it. But, the leak was always there, yet the gasket is fine.

RTV should do it. good luck sir.