Head gasket replacement and beyond,,

[More Power]

Not going to read back through all of this talk about TTY bolts so I will just throw in my thoughts:


There is quite a difference in clamping force yield between 125 lb/ft applied to and through the shank of a long bolt and through coarse threads using PST to seal versus a fine thread with a moly lube let alone the drag of the underside of a wide flange bolt.

I'm pretty sure we delisted the studs due to availability, price, and hassle. Not that I ever had an issue with telling someone they did not need something or biasing towards what I sold. If I were doing an engine that I wanted to last it would use studs.

I believe choosing studs or bolts could both be good choices. To back up that claim, I installed studs and bolts in two Duramax head gaskets projects in 2021. Both continue to perform normally. The head stud truck now has 15,000 miles on it since the service work.

I've shown two hot-shot RV hauler trucks right here in this forum that I saw personally. I even included photos of their odometers to prove what I was saying. And in one case, I included their GM service records. Both had in excess of 750K miles on their original engine, original head gaskets and original head bolts. That... is convincing evidence. I wish... that there were proven examples of 750K mile Duramax 6600 trucks that were driven all those miles with head studs.

Are you claiming more clamping force for studs?

More clamping load will Brinell (impress) the head gasket's fire rings even more into the aluminum head deck. The aluminum heads on my 2001 GMC's 140,000 mile Duramax required decking (removing) .003" to remove the fire-ring impressions in the aluminum head decks created in-part by the factory head bolts.

Second, the aluminum heads and cast-iron block thermally expand/contract at different rates. The head gaskets are designed to accomodate movement between the two deck surfaces. My 2001 GMC's head gaskets appear to have simply worn out due to a large number of engine heat cycles over 17 years of daily driving - the seal coat on the original gaskets appear to have been scrubbed away in a few areas. This (and the Brinelling) allowed combustion pressure to begin finding its way into the cooling system. So... What effect would more clamping load have on head gasket seal-coat life? We likely won't know till more are looked at over time.

Just thinking out loud...

Jim