Head gasket failure

[That Guy]

I just got the head back from the shop. Measure 0.007 of warp, no cracks, 6 bad valve guides (all exhaust), and the #6 exhaust valve was bent near the keepers.

The bad, no smoking guns as to why the gasket failed. Any ideas? Maybe I didn't get the head torqued correctly? It lasted about 10,000 miles before it failed. It did not mix with oil or get into the cylinders.

 

Unfortunately, I did not grab a picture of the gasket I pulled off, however, I have a doodle of the new gasket as to where it failed. 

 

The red is where the gasket failed, the blue is the path of the coolant. It failed near #2 and #5 and was starting to fail on #3&4. 

[CUMMINSDIESELPWR]

possible defective gasket or improper or missed torquing of headbolts?  thankfully it didnt get into a cylinder.

 

 

[LiveOak]

I just had the head gasket replaced on the wife's truck.  I didn't even want to allow the slight possibility (even then, anything can happen) for head gasket failure due to a bad head bolt or similar issue and had the shop install ARP head studs when they reassembled.  They did not charge extra for installing them and with head studs, you are likely to get the best possible head clam load distribution possible.  Still does NOT mean that the head gasket cannot fail again but in my opinion sure does significantly reduce that possibility.  I think they are worth the money especially if you plan to make any performance mods to the engine down the road. 

[That Guy]

Studs are in the future plans. I torqued to ~135 ft lbs this trip through, so far, its holding up fine, granted there's only 9 miles on it since.

[dripley]

I did mine back in April of last year. Re used the head bolts since they were still in spec per the Cummins bolt gauge. I went thru 3 torque sequences per the Cummins instructuons. 2 to a set ft pounds, dont remeber the numbers now. And the 3rd sequence was to turn all of them 90* more. Did it with 24" breaker bar. That last 28 turns of 90* more was a job. 35k miles later and its still holding fine.

[dripley]

Seeing the same error every where now.

[Jungledave]

#7 exhaust bent from install removal of head?   What boost on the head gasket?

[That Guy]

Bent from when the cam gear broke I assume. I had seen ~52psi at one point for about 1 second, but that was years before it failed. Normally a max of about 35psi. 

 

Short story, the previous owner had the kdp fall out and break the the timing case. So, like any farmer mechanic, they torched the cam gear to get it off the cam so they didn't have to pull the cam. Put the new case on and proceeded to torch the center  of the gear again. Fast forward about a decade, I'm doing 80 trying to keep up with traffic in Michigan and I hear a strange whistle. I pull off at the next exit thinking the exhaust came loose and I was hearing the turbo. Nope. Shut the truck off. Looked around everywhere, nothing. Fired back up and it sounded like hell. Shut it off immediately. Pulled the timing cover and found that the 3 spokes had broken and allowed the gear to slip about 60* out. It was still turning with the engine. 

 

It bent 7 push rods and shattered 7 tappets, and apparently (as the shop just told me), bent the #6 exhaust valve and toasted all 6 exhaust guides. They said it was bent just below the keepers. They checked all the other valves and they were fine, reground the valve seats as well. The exhaust valve wasn't leaking.

 

 

This picture was taken in Dec 2011, The gear broke in 2014 IIRC. I pulled the cover because the crack seal was leaking. You can see the discolored spokes of the cam gear.

Edited October 2, 2020 by That Guy