My 4.3 sounds exactly like my 3.1. On idle it's a definite piston slap. Before I was familiar with these engines I too thought it was a thrown rod, but after asking around I realized this was just the way these engines sound. It's much worse when it's cold, but you can still hear it after warming up. They've both been like that basically since they left the factory. FWIW internally everything was fine on both motors; pistons, valves, rings, compression etc. Just those dam med intake gaskets.
Hey not trying to hijack this thread buuuuuuut...
I thought after upgrading to a Fel-Pro it would supposedly solve any gasket leak that would arise in the future. I just checked my 3.8 and danged if the upper intake's leaking again, about 75k after I upgraded to the Fel-Pro. I should have just stuck with the factory style gaskets, at least I got 120k out of them. (BTW I used the proper bolt down sequence and torque ratings.)
Hey not trying to hijack this thread buuuuuuut...
I thought after upgrading to a Fel-Pro it would supposedly solve any gasket leak that would arise in the future. I just checked my 3.8 and danged if the upper intake's leaking again, about 75k after I upgraded to the Fel-Pro. I should have just stuck with the factory style gaskets, at least I got 120k out of them. (BTW I used the proper bolt down sequence and torque ratings.)
