Engine/Transmission (1994 - 1998) Very Strange Blow By situation...Rings??

[pwerwagn]

Leaning towards turbo bearing seals



--------------------------------------------------------------------------------



Check exhaust for oil residue. . If it is, sooner or later it will come into the light, it wil throttle up by itself...

Nah, it has a brand new turbo on it. And its had 2 others (Jammer BB and HX35) on it and done the same thing... .

I actually checked the downpipe last time I had the turbo off, about 3 weeks ago.



--Jeff

 

[Gary - K7GLD]

Not sure of the setup on your year truck - mine uses a gear driven vacuum pump mounted at front gearcase on the engine - if yours is the same - and maybe even if somewhat different - is it possible that a bad seal there could allow it to suck oil from the crankcase?

 

[pwerwagn]

I guess it could, but I am not really sure how that would cause it to go all over?? would it dump it somewhere?

I have had to replace a seal on the vaccuum pump once from a leak.

 

[Champane Flight]

Crack

Nah, it has a brand new turbo on it. And its had 2 others (Jammer BB and HX35) on it and done the same thing... .

I actually checked the downpipe last time I had the turbo off, about 3 weeks ago.



--Jeff

Maybe a broken ring? I would sure do a leakdown on it. . While your at it, scope each cylinder...

 

[LOtero]

hmmm this one really is a stumper there wagn... so are we taking the ol 12v apart or what, lemme know, also bring my turbo to work with you!

 

[cojhl2]

Back to the Turbocharger. . ,, or at least the pressure path.



I have heard of engines that are supposed to have positive cylinder charge and not getting it using oil. (a engine built for a turbocharger)



The theory is a negative charge pressure sucks oil up past the rings, or put more correctly the pressure in the crankcase forces it past the rings.



Since this uses oil only at low power output there is more of a chance to have negative charge pressure then when under load.



Therefore the symptoms you see.



Check that air path for leaks.

 

[Voodoo Trucker]

Had a company call me out to look at 2000 24V ISB 190 H. P. in a Freightliner 2000 gallon water truck using oil. Checked blow by tube and it had allot of blow by. Checked abuse history in engine ecm for engine over heat or low oil psi. No codes or anything showing signs of abuse. The company in framed the engine and found all 6 of the top compression rings broken. The only thing they did find upon tear down was no thermostat. The company bought the truck new from freightliner and had put all the hours on it. The truck spends most of its life in 1st and 2nd gear on job sites.

 

[pwerwagn]

Thats a good thought. I will have to pressure check the intake tract for leaks. It makes good boost on the freeway, even empty its at 10psi or so.

but I have never replaced any of the boots and it has a lot of miles. might check it.



I think I have decided its a ring problem though, or a cracked head. I know where the oil is going, out the breather.

as soon as my diag tools come in, I will give it a check.



thanks,

Jeff

 

[Moparsean]

personally i haven't seen a cracked head on a cummins 5. 9. Like you say,usually the fluids mix or you have an external leak. The gaskets I have changed have been external leaks,due to a broken head bolt usually. The ones I have worked on the most in my carrer are in OTTWA yard trucks (haul semi trailers from dock to dock). They work the livin crap out of them 24/7. That's how I knew I wanted a cummins in my truck. We did have one 24 valve motor,that one did need rings and was doing what yours is. The 12 valves were indesructable. . with the exception of a few head gaskets,due to extenal leakage only.



Have you tryed leaving it low on oil,like at the add line to see if it stays there longer. Maybe your stick is not acurate? I would put a small bottle on the tube (tie it up somehow) to catch it so you can measure how much is actually passing out.



You can also measure the blow by with a water manometer to see if its in spec or not.



Make sure there is no obstructions in that tube,some of them were a hard plastic and are not always routed real straight down. If its kinked at all,it will build pressure,then shoot it out all at once when the psi gets high enough. I have seen that once too. Take shop air and see if you can easyly blow up into that tube. Leave the oil fill cap off when you do this so you can hear it come out the top of the engine.

 

[rivercat]

how much blow by is excessive ? i have a good steady puff out of my extended heater hose that ends with a zip tie on the front axle and every time I cold/warm start I smell oil and get a white puff out the tail pipe. It seems worse with the edge on. With the edge off its mostly black out the tail pipe but still get the oil smell. The smell might be nomal just something hidden by the stock config. with the blowby tube ending at the bottle in front of the fan.