Watcha P-Pump cummins go Boom!

[oldestof11]

So much goes into blowing a head gasket. If I was to rate it:

Timing
Back pressure
Boost

But ask anyone on CF or Facebook, it is ALWAYS boost or back pressure.

[RCCUMMINS89]

The injector itself has a tremendous amount of play in it as well.

[fatty]

Also beating on it before it warms up is a large cause IMO.

Couples months ago a, guy I know with a 6 leaker spent thousands on fixing his blown hg "the right way"/bulletproof it (which wasn't a cummins swap, so not sure what he was talking about). He tells me last weekend it's pushing water past the overflow again. He's one of those guys who gets in the truck and puts the pedal to the floor.

[DMan1198]

Yup that is a sure fire way to blow a head gasket

[stillsmokin]

I've seen where drive pressure on a Cummins gets so high that the deck of the block comes off the cylinder barrels. I have been to a private diesel dyno in this country where there are holes in the walls and roof of the metal building from departed internal components of diesel engines. Good thing there was lots of beer to keep us warm since it was winter! In an ideal build the ratio of drive vs. boost should be 1:1 or less.

FWIW, a competition 12V is a whole different animal. It is usually entirely hard blocked to keep the cylinders from cracking from the increased cylinder pressures generated by high fuel delivery, 40-50 degrees timing, and massive air flow. Plain head studs won't hold the head down on the fire rings. Everything exposed to combustion is coated. It also has huge clearances to compensate for the heat and loose is fast, you've got about 5-7 minutes of run time before the oil temperature gets high. So you warm it up until it'll idle without puffing either into it (which is a project), shut if off until you're ready to go, or get out on the track and pull the trigger.

[shackwrrr]

If you watch close when it blows, the separation is below the timing case top. I believe this is a case of the block being ripped in half by pure pressure.