Example of some fine Cummins work quality

Any ISX 03 and newer sucks.

 

Up to 08 with egr only were pretty good. Have seen a lot with over a million miles

 

How do you "break-in" a head gasket?

I'm asking since I'm having a used head & new head gasket installed - this is on a volvo motor (if it matters)

Also, curious about the "re-torquing" of the studs...

 

In all seriousness though with the number of engines any engine manufacturer cranks out the door in a typical day there's bound to be the odd engine that fails right out of the gate.

 

Resurface both the heads and the block, I was always taught to oil up the gasket before putting it on, and the biggest and most important is torque in the manufacturers order. If I remember doing mine, you start out at 60 ft lbs, then 150, then the full rate. My numbers are off but it has it all in the book. It's a time consuming process, but pays off in the end. And the retorque is done by running 3 full heat cycles, then taking the covers off and checking each bolt, in order, at the full torque. That may not be how some do it, but I'm 22 and rebuilt mine by myself in my shop and it's got 100k or so on it and still running strong. Not very good at setting valve lash though

 

Do the "3 full heat cycles" require an actual road test? or simply idling to operating temp, then shut down, cool-off, rinse, repeat?

 

The old NH 195- 220 Cummins head bolt final torque was just shy of 500lb/ft. Or as tight as you could get 'em. The only good part was you had 6 bolts per head instead of 12.

 

They probably dyno them......

 

my dad told me that when I was a teenager when i replaced the head gasket on his 318 Detroit for the first time. I broke a head bolt an he said not that tight.

 

You’d be surprised how many head bolts needed to be retorqued after setting over night.

When we did mine, we torqued the head down acortding to spec, then waited over night and retorqued every headbolt in the morning and almost every head bolt needed another 1/8 to 1/2 a turn