Burning Oil question

[Reaver]

So I have noticed that I am burning oil but it only seems to happen at idle. It's intermittent and I never notice smoke after I accelerate from a stop or while cruising. Any thoughts to what it could be. I thought it was only when the engine was cold but it does it both hot and cold. I'm hardly the mechanic so i haven't done much in the way of diagnosing. I do know that cylinder 4 was about 20 psi lower than the other 5 during the leak down test (140# vs 160#). Could that be the issue? If it was a ring why would it not smoke all the time?

Thanks

 

[SHADOWII]

How much smoke are you talking about? Do you have to be standing near the exhaust to see it or is it a cloud?

 

[Reaver]

It's substantial.

 

[usetaboost]

Could be a bad turbo or bad valve guides. If it clouds on start up its guides and probably worn valves too. Mine does the same thing. Don't care, just gonna run it til it blows.

 

[SHADOWII]

Start w/the easy stuff first, check your pcv valve to make sure it is functioning properly and not pressurizing the crankcase. Remove the dn pipe and check your turbo and dn pipe for oil. Turbo seal may be going. Pull the plugs and check for gas/oil deposits. you can perform a compression test again at this point. When you get to the low cylinder, squirt some oil in the cylinder to see if the compression comes up. If the vave seals are leaking that bad, it should be smoking under acceleration as well.
Hope this helps.

 

[BOP4ever]

Turbo oil seal on the exhaust side was my issue. Same symptoms .

 

[v6turbo87]

There is no "oil" seal on the exhaust side of a turbo.

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[BOP4ever]

There is something like a seal In there . I paid Bison to rebuild the sucker and it's all good now.
Oil wad leaking by into the turbine side at idle . Saw oil on the wheel after removing the elbow .

 

[LEGACY_GN]

I've had a couple turbo seals go out with the exact same symptoms.

 

[earlbrown]

Pull your plugs out and see any one of them is glossy black. If it's #4, you're on the way to finding the problem.

 

[bison]

As you can see it's not really a "seal" since it's not a positive seal. It's an iron ring that conforms to a round bore on the bearing housing. It will not seal pressure. This type is the staggered gap style that minimizes leakage due to the gap being interrupted by the step. The ring should not see any pressure on the crankcase side. The ring is exposed to pressure on the ex side under load. Any restriction in oil drain back will surely cause oil to leak past this ring into the exhaust. The oil is controlled before the ring by a slinger that is machined into the turbine end of the shaft where it is slung away and drained back via gravity to the sump. Excessive oil in the area of the ring will result in oil entering the exhaust. It's not possible to "blow" a ring since it's not a positive seal and it won't be displaced by any of the working pressures it will ever see. It typically stops controlling oil when it loses tension, has a pitted bore it's trying to seal on, or is absorbing thrust due to the thrust end play being out of spec. There are a lot of reasons it could be exposed to any of those problems.


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[kidglok]

take the valve covers off and see if any of the seals rode up the stem.