thumper549

If you have good comp Numbers a good leak dwn test, then it HAS to be some thing else

dozer12216

I am also interested in the fix. I first would have said vacuum pump but he rebuilt that.
Rebuilding the vacuum pump will not cure a leak in the vacuum circuit!!! This was mentioned but not sure was fully followed up on...
Is it possible for compression to leak past a injector into crankcase?? Naw I don't think so. It leaks into fuel return and creats pressure in fuel tank.
Can compression leak past rings?? Yes, but a compression test was successful. Could a broken keystone ring (#1 ring) still seal. Well, Keystone rings don"t seal very well in non running condition. But the # 2 ring does seal in this condition.
Can valve guides/seals be this much of a problem. This has never been a problem with this engine in my opinion. Looks like a guide problem would cause a rough idle at least. A test procedure has been advanced previouslly.
A intake turbo seal failed could allow pressurised air to bleed into turbo oil return. Looks like would have a shaft with excess play!!!
How about a head gskt leak??? Overheating and coolant loss would also surely be evident.
What else are we missing???

thumper549

Nothing...Well except a manometer....to see when the preasure starts to build or is it pulses (pin hole in piston)
But I would think a leak dwn would have shown that unless it some freak thing that gets bigger as it gets hotter (don't think so)

thek0rn

so i swapped out the turbo for one off of my buddys 12v. when i took the one off my truck, i found oil residue on the compressor side. i took a few pictures so everyone could see what i found. i plan on taking the truck for a good ride tomorrow, so we will see what happens. if i still have a problem, i am going to take off all the rockers, and make a blockoff plate for the intake, with a regulated air source to see if the guides/seals are leaking. i will keep everyone updated.

thek0rn

well i drove the truck to work for two days this week, 50mi round trip. the first day i drove easy, and there was no oil under the truck. so i steam cleaned underneath, and drove home. tuesday, i drove to work a little harder, and checked it before leaving work. there was oil everywhere. so the turbo wasn't the problem, even though it was a little wet. i will check valve seals on sunday and see what happens.

flatline racing

The compressor side will always have a little oil on it, after all there is a vacuum there. If it was a compressor seal problem, you would have more than likely experienced a run-away....thats always alot of fun. With a turbine side failure, everything behind you is full of oil, like fueling for 1000hp with no air.
You have a valve seal problem. Ring seal is good, compression test shows that ( leak-down test is a waste of time in my opinion ).

nitrousn

A diesel does not have vacuum. Leak down is a very accurate test of ring seal or any other combustion chamber leaks. The manometer is cummins accepted way of determining ring seal and a good test at that.

The original poster of this thread has a serious internal problem. Some people refuse to accept what is obvious and slapping them in the face.

logskidder

When your in there checking the valve seals, try to measure the stems. They should be no less than 0.3126 or 7.94mm. The guide should be no larger than 0.3185 or 8.090mm.

thumper549

If you drove it EZ..the only thing that could change in the internal would be the work of the rings..(piston) all other things would stay the same IE compressor,valve stem seals,ETC
(with a slight chance of turbo issue) but you swapped that ?
So..I think you are at a pin hole or busted ring

thek0rn

the problem seems to only happen when i spend time at higher boost levels and when i drive it hard, the boost is usually up higher. that puts more pressure on the runner side of the intake valves. if i had a bad guide, the boost presure could pass up the guide, past the seal, and into the valvecover, even with the valve closed.

i did replace the turbo with another hx35 that is known good.

im not doubting that i have a problem in the short block, but i wanna check everything i can before i have to pull the head off and dig in deep.

thek0rn

and i would do a manometer test, but all specs i have found are for industrial engines, and need to be done on a dyno at full load.

nitrousn

For all you know it may not pass at idle. I will look in my mopar/cummins fsm's, but I do know the earlier manuals illustrated the manometer test.

logskidder

Give me a day and I'll get you the specs.......you can run a hose into the cab and have someone watch it while you drive. I doubt a shortblock problem.

flatline racing

The compressor side of the turbo (intake) has a vacuum, it has to pull air through the air cleaner. Like I said, leak down is a waste of time, for the cylinders. It does have uses though.

logskidder

I knew what you were talking about