Got a real blow-by puzzler here......

[JJFlash]

So a couple of years ago, my 06 Mega Cab (198,000 miles) started spitting oil out of the crankcase vent. It began on a trip through Washington state, pulling a heavy trailer up many steep passes. EGTs were high for most of the trip, but still under the danger zone. Oil coated the trailer and my tailgate. I feared the worst.....

Once home, I couldn't find any of the usual symptoms (huffing or chugging out the valve cover cap) that could be attributed to a broken ring or holed piston. Further, as long as I simply drove around town, the problem stopped. It only happened when towing heavy at boost.

We just sold some property and I have a little extra $$ to spend, so I took the truck to a (reputable) local diesel shop. Even under boost (standing on the brake and under throttle) we couldn't get it to huff out of the valve cover cap. They checked under the valve cover to see if anything was amiss with the vent, but all was well. Finally, they removed the injectors and did a compression and leakdown test. Compression was great. They are adjusting the valves and buttoning it back up as we speak.

What the heck is causing this?

Is it possible that my turbo is leaking boost when fully spooled (like when towing) and pressurizing the return line? I do have a boost-fooler installed, as well as a mild tow tune, but it's been that way since 2008 without issue.

Any ideas?

 

[Tuesdak]

I would step back and re-evaluate the situation. You have fixed yourself on the engine and blowby tube, but, I don't see the exact reason you have done this. Perhaps the oil is from something else?
Specifically transmission, axles, etc? Then consider it's just an oil leak vs. something caused by blowby. Any engine that works hard is going to have more blowby and oil consumption so the road draft tube may have more oil on it from this alone and be misleading you. I am not there looking at it, but, it is just a thought of something being overlooked.

The case, POV, I am thinking of is a transmission low on oil, but no leaks. Oil everywhere on the underside because the oil was boiled off from slipping clutches or a spun bearing and exited the vent tube as a vapor then condensed on everything else. In this case the trans has burned up due to miles or abuse, now is low on oil, and the lack of a leak has everyone scratching their head as to how the oil got out and all over everything.

Off the cuff something may be getting too hot in the engine like a plugged piston oil squirt and boiling off oil. Have you done a UOA to look for oddball things? Oil that's been overheated will show up in a UOA.

 

[JJFlash]

I have looked for other leaks, but have not found any. All other fluids are up.

Again, it does not show up under regular use, just when towing. When initially parked after towing, you can clearly see oil dripping from the vent hose.

 

[rscurtis]

Don't rule out leaky valve guides, as that will allow boost and drive pressure to leak into the crankcase. They won't show up in a compression or leak down test. I suppose that boost or drive pressure could be leaking into the turbo oil drain, but I would think a problem there would go the other way, with oil going into the turbo.

 

[cerberusiam]

Diesel leak oil, it is their nature. They leak more oil when you work them hard, thats is also their nature whne they have less than adequate oil separation for the CCV. The oil separation is underwhelming on that truck to say the least. I almost always see more oil spotting when towing loads than runnign empty but it should not cover the underneath of the truck or be more than spotting on the tail gate.

Broken rings have proven to be very hard to find at times, and, they will almost always show under extreme conditions rather than in the shop. A leak down test is not always a given and not really recommended for finding issues like this. Thery are hard to administer evenly and don't always tell the whole story. Variances attributed to temp or normal can very well be some thing else.

There have been several cases where the ONLY indication of broken rings was excessive oil being blown out the CCV under load. Not many have gone to the extent of testing you have, but, the tests are not always conclusive because of the extreme differences between shop running and loaded running. Could be something simple as stuck rings also that won't show with tests but can impact loaded operation.

Could be the oil you are running also, just another thing that can contribute. If it was me I would put at least 1 and maybe 2 quarts of MMO in the crank case and drive it for a while thne drain and refill with a good 14-40 Diesel oil like Valvoline Premium Blue or Delo 400.

 

[Wingate]

Did they borescope cylinders while injectors were removed? I would also second an oil sample being sent off immediately. Have you removed the tune and boost fooler? What is MAX boost the engine usually sees with the mods installed? What is the max egt it sees with mods and towing hard?

 

[Prairie Dog]

It's completely normal to have a few drips from the draft tube. Your truck always had at least some oil come out there unless it was like my truck and the oil separator on top of the rocker cover simply leaked it down the sides of the engine instead of out the tube.
As was said before, all engines create a little blow by and of course it's worse when it working hard. Yours does not sound excessive.
I don't think there anything wrong with your truck.

 

[DanielCrawford]

How is your exhaust pipe, oily. or just normal. take a look at your turbo. Is it puking oil? maybe your turbo seals are leaking. Check the shaft play both axial and radial play. If it is excessive your seals could be bad. Just a thought

 

[ProLean]

Cerberusiam....could you do me a favor and explain your comment about using MMO in the crankcase? I know it does a pretty good clean up job but can it hurt my truck if I do it? How long would you leave it in there before changing it out for a new oil and filter? I have had somewhat the same issue with my truck puffing a bit of white smoke from the CC breather after towing my TH and sometimes just coming home from work and parking in the garage...I smell the oil. I am using PB 10-40 or Mystic 10-50. I live in AZ so I thought the 50W might be of some benefit in the heat.
I'd like to try the MMO if you think it would help clean up the CC and maybe help unstick something. Power is good and only smokes when I roll the coal. I am using a Smarty SO-06 tuner with the 90 HP SW (#5) Stock extra deep WIX filters on the intake.
Sorry to hijack a thread but mine sounds similar.
Thanks!

 

[cerberusiam]

In AZ where it is always warm the 50W oil may have a usage. Just not sure the benfit is worth it. Certain oils seem to create more vapor, and sludge, when used in certain conditions it is hard to tell if that is an issue. Premium Blue 15-40 is Cummins choice so tend to stay with that.

Periodically you will find an engine that you cannot check the oil correctly because the a gob of something sticky is lodged at the end of the dip stick tube. A quart of MMO in the crankcase and run it for a while will almost always solve the problem. I have done it several times and have not seen any issues with MMO in the crank case for a limited time. I usally run it the last 1000 miles before an oil change and call it good. You could probably achieve the same effect with 2 or 3 heat cycles thne dump the oil. No data on how long to adequately clean internals, or even what quantifies adequately clean. YMMV.

There are so many factors thta contribute to vapor from the crank case it is hard to tell if it is a problem or normal. In cool weather it is normal, same as drip or 2 from the breather tube. Damp conditions will be worse, dryer and warmer the better. Usage also makes a difference. If you don't get the engine to full operating temp some sludge buildup or carboning on rings\injectors could occur. Same with using JUST fuel and no additives, probbaly worse in the warmer climes as there is NO need for treatment.

The fact is the typical run of ULSD is really sad fuel in a lot of ways. It burns cleaner but that comes at a price of other reactions that may not be so good. The emissions design of the engines does not help. All I can say is I have had excellent luck runnign the MMO periodically to keep internals clean (I run a quart in the fuel mix about every 3rd mix to clean the fuel system up), running additives in every tank, and when not towing heavy frequuetly an injector cleaning with SeaFoam.

There are those that will claim most of what I have done is wrong and will hurt the engine and claim what I have done will make no difference in the long run. All I can show is the results, +240k and uses no oil whne driven lightly and minimal when worked hard over 7k intervals. The stock injectors went 205k with no issues, mileage still good, no hard starts or smoke. They were NOISY so I put a new set in, proactive maintenance as the noise was wear. They even looked good on contribution tests.

If it blows up at 260k I am blaming lack of control over my right foot.

 

[mfurrh55]

My brothers truck started doing same thing when towing up a grade, finally switched out turbos and it quit, it was leaking oil past his bearings in the turbo, Monte

 

[Tuesdak]

Cerberusiam....could you do me a favor and explain your comment about using MMO in the crankcase? I know it does a pretty good clean up job but can it hurt my truck if I do it? How long would you leave it in there before changing it out for a new oil and filter? I have had somewhat the same issue with my truck puffing a bit of white smoke from the CC breather after towing my TH and sometimes just coming home from work and parking in the garage...I smell the oil. I am using PB 10-40 or Mystic 10-50. I live in AZ so I thought the 50W might be of some benefit in the heat.
I'd like to try the MMO if you think it would help clean up the CC and maybe help unstick something. Power is good and only smokes when I roll the coal. I am using a Smarty SO-06 tuner with the 90 HP SW (#5) Stock extra deep WIX filters on the intake.
Sorry to hijack a thread but mine sounds similar.
Thanks!

Mystic 10w-50 is what I dropped in mine as it was on sale, had some on hand anyway, and well it's AZ where cold starting temperature is usually over 100 degrees. Winter weights are still 10w so no real change. Yes, a thicker oil does help out here esp. if you are like me and overheat oil to the point low oil pressure alarms go off. (Although that event was on a GM.) The extreme grades being 6-18% here in extreme 121 degree summer heat bends the minds of most who haven't experienced AZ. (I have been to below zero and know that is a different ballgame for oil and starting things.) Mystic Stinks less than Royal Purple... I have had luck with it raising hot oil pressure at idle in a couple diesels say extreme temps, AC on, and cooling fan locked up.

I even switch out to the 85W-140 diff oils due to extreme heat. And don't get me started on 2 year max battery life with 3 years pushing it.

The CC breather vented under the engine is a trade off rather than dumping it in the intake and: in the turbo, CAC and plumbing and oiling up the CAC boots... This breather arrangement being just a tube vented to the air, after a black box of questionable value, takes getting used to as the alternative is nasty oil dripping intake piping. I always smell oil in the garage and yes some is from parking the Cummins. Different oils appear to vary the odor a lot.

MMO is really thin and more of a fuel tank cleaner. Think of MMO being tested with other diesel fuel lube and not doing well there. I would only idle the engine with no load to clean out with MMO and then drain it and change filter back to diesel oil.

10 weight oil is good for cleaning out soot, again, at idle only. Least that's what I do to clean out dirty 6.2 GM's. I have seen too many copper colored main/rod bearings to load an engine on thin 'clean out' oil. I don't even want to think about thin oil and turbo bearings.

 

[DonFitzwater]

Don't rule out leaky valve guides, as that will allow boost and drive pressure to leak into the crankcase. They won't show up in a compression or leak down test. I suppose that boost or drive pressure could be leaking into the turbo oil drain, but I would think a problem there would go the other way, with oil going into the turbo.

X2 on the valve guides. My old 98 12 valve blew tons of oil out the vent tube until I r&r'd the cylinder head. After that, just a little drool as usual. Mileage was right around 200k.

 

[mfurrh55]

You can run marvel mystery oil in fuel or engine , doesn't hurt anything, friend was fixing to trade his mothers car in and it was smoking a little, put in quart of MMO and it quit smoking long enough to trade it in