shakenfake

I use ARP chromoly bolts now

Bgbldodge

Guess I'm lucky but the bolts in my '14 came out with zero issues. So did the 35yr old bolts in my blazer.

shakenfake

Yeah my '99 5.3 had no bolts break off. My 04 6.0 had one that was broken on it's own. Both TX trucks.
My '96 Impala had 4 that broke off on their own.

arthursc2

iTrader: (5)

Blazer ran for 5 of those years, doesnt count

RedXray

On my LQ9 from the salvage yard (2017)...
first thing I did was spray the factory bolts with CRC a couple times before tear down and had no issues.

01WS6/tamu

iTrader: (36)

Cats start plugging then manifolds run waay hotter and bolts start popping like popcorn. See it all time on HD trucks and any half tons with 6.0, 6.2 that are driven we'll say spirited. If they are old fart driven all the bolts usually stay in place.

54inches

iTrader: (4)

I believe part of it has to do with the steam port setup on some vehicles.....

shakenfake

@54inches I'm not sure what correlation there would be there.

54inches

iTrader: (4)

Short answer; context clues were the correlation for me.

Long answer: Heat spots on those back two cylinders, which is where most people see the broken bolts. Consequently, those that have the factory and/or aftermarket 4 corner steam port setup
as opposed to the 2 port, do not seem to have the incidence of the broken bolts as much.

strutaeng

Never heard of steam ports being the cause. What about broken exhaust manifold bolts on engines that didn't have steam ports?

They seem to break at random locations in my limited observations. As far as I know, it's because of thermal expansion due to different coefficients from the dissimilar metals. Older cast iron head seemed like was less of an issue (also had cast iron manifolds) but still happened. Of course, the cycling of heating and cooling contributes as well.

I started putting that copper based anti seize when installing them, but don't really know if there's any benefit to that TBH.

I'm glad to hear the aftermarket bolts hold up better than OEM ones....