Smoking Exhaust

[Derek-G20]

I'm hoping to tap into the experience of our members. I have had a problem with my van (6.2 NA) smoking for a few years and it has been getting progressively worse. Here are some of the symptoms:
- Blue/light gray smoke coming from the exhaust pipes, especially under load
- Oil droplets on the body above the exhaust pipe tips and black sooty dots on the back doors (I believe from the exhaust)
- Burnt oil smell and oil in the intake manifold (appears to be coming through the crankcase depression regulator (CDR))
- I have some minor oil leaks, but I end up adding approximately a quart of oil every 1000-1500 miles. I believe the volume of the leaks are less than the volume that I add.
- Approximately 250,000 miles
- Coolant level does not drop

I think it is conclusive that I am burning oil (if you think there is a chance that there is another issue, please let me know.) I ran a check on the CDR, which met the testing specs perfectly. I replaced it anyhow and it made no difference in the smoke coming from the exhaust or oil droplets on the body. I did a compression test, here are the results:

1 - 382
2 - 370
3 - 370
4 - 402
5 - 379
6 - 380
7 - 382
8 - 402

I am out of spec (should be 380-400 each cylinder). I don't have enough experience to know if this type of result is bad enough to lead to the oil consumption that I am encountering. I'm guessing some people here can comment...

I am relatively certain that I have a fair amount of oil coming through the CDR, as evidenced by the oily and burnt-oil-smelling intake manifold. I am thinking that I may have a large amount of blow by, which ends up as a large volume of oily air coming through the CDR and back into the cylinder.

I guess I am trying to figure out with certainty the cause of the oil burning. I am guessing it is worn rings/cylinders. I'd like to avoid a rebuild, especially if the rings/cylinders are not the issue. I am hoping that there could be another cause. Valve seals? Any advice or comments would be appreciated. Thank you!

[DmaxMaverick]

Your compression looks fine. The spread is only about 8%, and 370 isn't too low. Note that the specs are for a new-ish engine.

Oily, messy intake manifold is normal for 250K miles. Worse if it has EGR (vacuum pod in the middle of the intake, hardens the oil). Oil leaks, in general, are normal. They can be sealed up, but will leak again in another 250K, more or less.

It may simply be the brand and/or grade of oil you're using. Some oils vapor and burn more than others. It could also be restricted intake plumbing, such as dirty air filter, rodent nest, or collapsing ductwork, which increases intake vacuum, increases oil vapor from the crankcase, and reduces air volume. Oil through the engine is just more fuel. It will burn it the same as #2. Smokey exhaust due to oil would be after combustion, such as a valve guide (more typical of a failed turbo, but you don't have one). Too much oil, and turning it off wouldn't turn it off. Your engine will run on straight motor oil and not complain one bit.

[JohnC]

Your oil consumption, by itself, is not out of line. I had a Ford 7.3, a '93 GMC 6.5, an '95 GMC 6.5, a '06 GMC 6.6 and a Mercedes 3.5 OM603. They all used a quart in about 1500 miles. The smoke is a different story. I've never understood how a Diesel could blow blue smoke unless it oil was introduced after the combustion process, so maybe exhaust valve seals, but I would think the pressure would force the oil back into the engine, not out the tail pipe.

You may have an issue with oil control rings, but I doubt it would be cost effective to try to replace them. Get Shell Rotella from Wal*Mart and save the rest of your money for beer.

[Derek-G20]

Rats! I didn't have any blockages in the intake ducting. Thanks for the comments guys. Maverick, I was excited to go check the intake - it was a good idea to check that for blockages. I can see how that could lead to more oily air getting pulled through the CDR. The air filter is newer and the smoking has been happening over a number of air filter changes, as well as a number of oil changes. The brand/quality of oil does make a difference on the amount of smoke. I have used many different kinds, all 15W/40, including anti-smoke additives and synthetic oil. There are slight differences in the amount of smoke from the tail pipe, but no matter what I use, the smoking is pretty darn heavy. I mean, when I am going up a medium grade on the freeway the smoke trail that I leave is substantial - totally visible and enough to make me worry I'll get pulled over at some point. I don't notice any performance issues - it's just smoking a lot. Another time that I notice it more than others is after sitting in traffic, or after idling for a long time, then when I open up on the accelerator, there is more smoking than had I not been in the traffic or idling for a long time.

[Robyn]

When was the last time the injectors were replaced.

The problem may be more of an injector issue than an oil burning one.

1 Qt of oil in 1000 miles is not terrible.....

The blueish smoke sounds like worn out injectors...."Peeing a stream" rather than spraying a nice fine mist.

The high miles could ALSO be showing some timing chain stretch and the injection timing is a tad retarded....

Combination of a few things...

[Derek-G20]

Thank you for the comments. The injectors have not been replaced for as long as I have had the van (approximately 8 years and 80K miles). Also, I have not replaced the timing chain nor do I have any records on that. I am guessing that the timing chain, and maybe the injectors, is original.

I do have a lot of oil that ends up coming out of the tail pipes and ending up on the body panel above the pipes as well as the back of the van (see attached pic). I was also under the impression that "blue" smoke was from burned oil. I thought that if a diesel had unburned fuel that the smoke would end up being dark gray or black.

Testing the injectors would require a pop test? If it turns out that the injectors are worn out, would you rebuild or replace them?

Thanks for the good ideas/comments. I'd love to be able to address the smoking issue and have it not involve a rebuild.6206

[Robyn]

The spots on the paint may be more soot than actual oil.....

IF YOU CAN FIND A GOOD SHOP...GET YOURS REBUILT