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Big Cam Cummins intermix

14525 Views 9 Replies 4 Participants Last post by  NP
Ok, here goes the dumb question of the day. But, I since I don't know I have to ask. My neighbor has a Big Cam Cummins in an older C/O and it started intermixing oil and water. He had another mechanic friend briefly look at it and advised him on what to do, because he did not have the time to fix it. He said pull the manifolds and see which cylinder is bad, pull the pan, the bad cylinders piston and the cylinder head of the bad cylinder. Then replace all bad gaskets and reassemble. I understand the head removal, but why the piston? I'll probably be doing the work on this engine and don't want to take things apart that don't need to. Thank you in advance for all input.
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I'd say something was lost in the translation. It could be a anything from a leaking head gasket to a pitted (leaking) liner. If it's the latter, then yes, liner kits would have to be installed--pistons, rings, liners, etc.
Sometimes you need a sleeve puller, many times you don't. You also need a torque wrench that's in the 250+ range. If it's a mechanical engine, you need to know how to run the rack after re-assembly, know how to heat the pistons to fit wrist pins, etc, etc. Feeler gauges for adjusting the valves, inch-pound torque wrench for setting the injectors, and on and on. If it has a Jake Brake, the O-rings should be replaced, and the Jake Brake solenoids have to also be adjusted.
No offense, but if you've never been into one before for major surgery I'd strongly advise you to have a guy who's experienced with the 855 cu. in. engine types leaning over your shoulder. I'm not being critical, but over the years I can recall a couple times where a guy was unaware of a small procedure he should have done on an O.H. and it turned into a $25,000 mistake the shop had to pay for.
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You're certainly welcome.
I might be doing the bigger favor and letting someone else help.
Right, I guess that was my point in a round-about way.:) Nothing worse than getting in over your head then having to call in outside troops. On the other hand, if you guys can round up someone who's worked on them, I know you'd enjoy jumping in and getting to know a "Three-headed Pig" as we used to call them. They're a great engine to both work on and drive down the road---always been my favorite. Years ago a fully loaded semi pulled into our shop with a 335 (same engine, basically) with a fairly loud knock. When we got it torn down, believe it or not, it had limped in under it's own power and yet the crankshaft was broken in two at the 3rd or 4th main brg journal---fun stuff!

Hopefully you guys find something minor and not too spendy.
My two semis have a head of now, seeping to the outside of the block.....
That was very common with those engines. We used to re-torque the heads all the time. You might give that a try.
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