Hey all, new to this forum as I've never worked on a chevy before but here we are. My neighbor was told by the local dealership that is 06 impala with the 3900 v6 and 110k miles had a leaking head gasket and a sticky valve, for which they quoted him 1800 to fix. I offered to have a go for a lot less. So i get the car and I'm just not sure there's anything wrong with the head gaskets or the valves. the check engine light was on so i scanned the codes and got some emissions system leak codes. Cleared them, drove it for awhile, no problems. I remember that it occasionally surged at idle but other than that I can't fault the way it drives at all. There's no puddles underneath, no oil in coolant, no coolant in oil, no white clouds out the exhaust, nothing. How do you confirm that one of these engines has a head gasket leak when it sure isn't acting like it? Hate to give it back to him and then it turns out it did have a problem. Thanks

 

A cooling system pressure tester is said to be able to test head gasket failure.

Cooling System - Stant

See the instruction manual.

A surge would sound like a vacuum issue possibly.

Did you look up the codes rather than just clear them?