Urgent: Where's my oil going?

[Piker]

Quick recap:

Last summer we did a 6200 mile trip out west. Used a total of 1 quart of oil, and the engine ran great the entire trip. Got home, changed oil and straight piped the exhaust and got ready for the next trip.

Last Christmas we drove to florida from pa... about 1100 miles. We lost 1 gallon of oil on the trip down... and then another gallon of oil on the trip home. There was oil sprayed up the back of the rv so I suspected a massive leak somewhere. Turned out there was a crack in the oil pan. I fixed the crack, and no more leak... no more splatter up the rear of the rv. I thought our problems were solved.

Ok, fast forward to today... we're in Florida again. And once again we lost a gallon of oil on our trip down here. No splatter on the rear of the rv, and no apparent leaks underneath, except for the occasional drip here or there. Nothing wet. It's bad enough that in the last 250 miles, we lost 2 quarts.

I was thinking the worst... blow-by from a cracked piston or damaged rings. But when I pull the oil filler cap off, there's not really much vapor coming out. I've seen guys with bad blowby set their oil filler cap over the hole and it blows right off... I've also seen them "chug" when there's just one bad cylinder and you get a huge huff out the filler hole when that cylinder fires... my engine has a nice soft steady vapor rolling out of the slobber tube... and hardly a drip of oil comes out... regardless of engine temperature or rpm.

I also checked the exhaust side of the turbo after letting the engine high idle for 10 minutes or so... no oil. And no oil on the compressor side either.

Also, no oil in the antifreeze.

So where in the heck is all this oil going? Could a valve seal have given way that quickly? The engine is running great, and I never see any blue smoke. Only a haze when the engine is cold (raw fuel, but goes away after warmed up) and a puff of black when you get on the throttle until the turbo spools up.

I'm stumped... Help me out here.

-cheers

[Ray,IN]

The most obvious thing, from reading here, is actual oil level compared to what your dipstick reads. What is the oil capacity of the oil pan + filter? Did you pour-in that amount when you changed the oil? If you did, what did the dipstick read immediately after you ran the engine to inspect for any oil leak at the filter? The aftermarket dipstick that is used by the MH builder can be marked incorrectly.
Another possibility is the oil seals in the turbo leaking at speed, and the engine is simply burning oil as fuel premixed into the air charge.

[Piker]

The dipstick reads the correct level when you change the oil and refill with the proper amount.

Is there any real way of knowing if the turbo leaks only at speed? This sounds like a plausible reason for using so much oil. I can't come up with any other reason for so much oil to disappear so quickly. I would think if it was going into the intake that I would see some oily residue on the compressor side of the turbo, but there's nothing. If the leak is on the exhaust side of the turbo, it would be much harder to detect, especially if it was only leaking at speed...

Sure seems like I should be seeing some smoke with this kind of oil usage... especially if it was leaking into the exhaust side of the turbo as that wouldn't be a very efficient burn of the oil. If it was leaking through a valve seal or something, it seems like the oil would just get burned up like the diesel fuel and there wouldn't really be any signs of it. I dunno... just thinking out loud.

I've been running higher boost levels than stock, but nothing crazy... maybe for the trip home I'll turn everything down (boost and fuel) just to be on the safe side.

thanks for the input.

-cheers

[Coma]

Are you letting it set overnight to measure the oil quantity?

[Piker]

Originally Posted by Coma

Are you letting it set overnight to measure the oil quantity?

Yep.

I got some responses to this question on the dodge cummins forum... Apparently the turbo can eat all kind of oil because of a bad seal and you'd never know it. It could only be leaking under load... and it may only be leaking on the exhaust side... and once the turbo is up to temp, it can actually burn the oil almost completely and you'd never see smoke... or much of it anyways. At least this is what I've been told.

Seems plausible.

Not much I can do about it down here in Fla... just enjoy the rest of vacation and hope it gets us home. I suppose I could have a new Turbo drop-shipped to our campsite... it would only take a few minutes to put on... but probably won't go to that extent.

-cheers

[Coma]

If it's not on the outside of the motor, toad or back of MH then it's going out the exhaust. Mechanism for that could be turbo seal or exhaust valve seals. It might only be one valve seal. Fwiw, what ever boost you see your exhaust pressure is approximately double. In the extreme you can get valve float. Valve seals are at risk also. On the ISC exhaust pressure is limited to about 60psi in part to prevent exhaust side valve train issues.

[Piker]

Originally Posted by Coma

If it's not on the outside of the motor, toad or back of MH then it's going out the exhaust. Mechanism for that could be turbo seal or exhaust valve seals. It might only be one valve seal. Fwiw, what ever boost you see your exhaust pressure is approximately double. In the extreme you can get valve float. Valve seals are at risk also. On the ISC exhaust pressure is limited to about 60psi in part to prevent exhaust side valve train issues.

So do you think that even just one bad exhaust valve seal could show as much oil loss as we're experiencing? Almost a quart in 100 miles?

If there's a possibility that it's a valve seal, I'll hold off swapping the turbo until I put new valve seals in. Valve seals are easy and cheap... turbos... not so much.

-cheers

[Coma]

Originally Posted by Piker

So do you think that even just one bad exhaust valve seal could show as much oil loss as we're experiencing? Almost a quart in 100 miles?

If there's a possibility that it's a valve seal, I'll hold off swapping the turbo until I put new valve seals in. Valve seals are easy and cheap... turbos... not so much.

-cheers

If a quart were coming out of the turbo seal I would think you could see it slobbering, a peak in the the turbo outlet might confirm or deny. Valve seals…how many miles on the motor? I would think it would be more than one seal that is leaking.

[Piker]

Originally Posted by Coma

If a quart were coming out of the turbo seal I would think you could see it slobbering, a peak in the the turbo outlet might confirm or deny. Valve seals…how many miles on the motor? I would think it would be more than one seal that is leaking.

I did have a peek at the turbo... both on the exhaust side and compressor side. Dry as a bone on both sides. I even let the engine do a high-idle for a bit before checking the exhaust side and nothing... no visible traces of oil. The impeller shaft had the normal up and down play typical of this style of turbo which has basically a bushing just like a rod or crank journal... the in and out play was less than what you could feel by hand.

The motor now has 87,000 miles on it... but it's 20 years old. I suspect any number of seals could be dried out after that much time.

The weird thing is that this oil usage seems to have started suddenly. Like I said earlier... 6000 mile trip out west and back and only 1 quart of usage. Suddenly I get a quart usage every 100 miles immediately after that trip. Only thing different from the first trip to the second trip where we saw the oil usage was a straight piped exhaust. I thought maybe the difference in back pressure might have stressed the seal differently and caused it to leak?... I dunno. Just thinking out loud...

-cheers

[Coma]

You seem to have covered the obvious stuff. A quart per thousand miles is a lot but probably in spec. A quart in 100 miles will have to be fixed, let us know what you find.

Good Luck!

[Piker]

Originally Posted by Coma

You seem to have covered the obvious stuff. A quart per thousand miles is a lot but probably in spec. A quart in 100 miles will have to be fixed, let us know what you find.

Good Luck!

thanks... gonna need it with this old thing...

-cheers

[Papa_Jim]

The engine went 6200 miles on 1 quart of oil. Then you changed the oil and straight piped the exhaust. Now the engine is going through oil like crazy.

Well, considering those facts, it sounds like either the engine doesn't like the oil you're giving it, or it doesn't like not having some exhaust back pressure.

You might try a different oil. You might try putting a muffler on it.

It's like shooting arrows into the wind. You might get lucky and hit something.

Jim

[Piker]

Originally Posted by Papa_Jim

The engine went 6200 miles on 1 quart of oil. Then you changed the oil and straight piped the exhaust. Now the engine is going through oil like crazy.

Well, considering those facts, it sounds like either the engine doesn't like the oil you're giving it, or it doesn't like not having some exhaust back pressure.

You might try a different oil. You might try putting a muffler on it.

It's like shooting arrows into the wind. You might get lucky and hit something.

Jim

Well, I've always used Rotella 15w-40, so that's probably not it.

It sure seems like the turbo is the issue, but man, I hate to spend that much money if it's not the issue. If it is leaking, it must only be leaking under high boost when the EGT is hottest cause it just doesn't seem to smoke. Not as far as I can tell anyways.

I dunno what to do. I think I'm gonna try to get home with it so I can explore other possibilities.

-cheers

[D Lindy]

Go back to the old exhaust system and drive it for a while an see if the oil usage drops, if so then you know it's a straight exhaust system issue