Need a second option on this. I have a small amount of coolant running down the side by the alternator. I have no oil or coolant mixing either way and never gets hot, just have the swinging needle that moves with engine load. I don't think its the HG because I have some coolant that looks like its seeping from the side of the housing and what looks like seepage from the very top bolt on it. I tried tightening but its tight. Is it possible for these to leak?

 

yes it is clean it with break clean and blow dry with compressed air have some one stuff a rag and the blow gun in the filler neck on the rad and charge it with 10-20PSI while you look for leaks if you find thats its comming from the t-stat then unbolt it and reseal it with silicone i would also change the stat just for fun since you there

 

Good idea using a blow gun, I never thought of that. If it tuns out to be the head gasket Ill be ordering from you.

 

The housing has a 1 inch round rubber seal it goes through the engine hook and on the back of the t-stat. I just replaced mine for the same reason the small leak, and well its -25c out there and after running for about 3 hours the damn truck was still maybe -25c inside all fixed now