Leaky turbo seals OM617.952 - PeachParts Mercedes-Benz Forum

eatont9999 · #1 01-26-2015, 09:37 PM

Well, I came home this evening and noticed a strange marking on the driveway and once I got close enough to make it out, I knew exactly what it was. I have long suspected the turbo seals on my grey 300SD with a KKK K26 turbo of leaking into the intake due to the rich, burnt oil smell and spotting on the back end of the car. I think this finally proves that theory beyond the shadow of a doubt. I believe I revved the engine sometime last weekend and I don't even remember why but the pattern in the pictures clearly indicates some higher RPM exhaust flow. No OM617 in proper running condition blows oil out of the exhaust pipe; no matter how much you rev it up. Soot and junk, maybe, but this ain't no soot.

BenzTurbo · #2 01-26-2015, 10:46 PM

damn! are the kkk's known to have seal problems? did you have any blue smoke as well?

eatont9999 · #3 01-26-2015, 11:05 PM

Quote:

Originally Posted by BenzTurbo

damn! are the kkk's known to have seal problems? did you have any blue smoke as well?

I have never heard of them having any more problems than the T3. Both of which are not prone to problems to begin with. My best estimate on this car is at least 400K miles. Given how poorly the car was treated before I took ownership of it, I highly doubt the turbo was ever serviced during the life of the car.

No blue smoke. Diesels will consume engine oil as fuel, so it gets burnt in the engine. Most cases result in a grey haze that can progress to black smoke. Mine is more of a grey to dark grey haze. I have noticed more clouds of grey exhaust gas when taking off from a stop. Also, high RPM down shifts cause more haze. Mostly noticeable at night since the haze can be lightly colored.

The only concern I have with this issue is the possibility of a runaway situation. Has anyone ever run into that with a turbo in this condition? I know it is possible but I don't think mine is anywhere near that point yet. Is it possible that the seals go completely and I find myself with a runaway situation?

Mxfrank · #4 01-26-2015, 11:56 PM

It's possible to get a runaway, but not likely. It sounds odd, but there's not much oil pressure in the turbo capsule. This is because a very narrow diameter oil passage opens into the bearing area, which drains into the sump at atmospheric pressure. The drain pipe has an ID that's maybe ten times the input pipe. This results in sort of a low pressure spray. What pressure there is, is counterbalanced on one side by exhaust pressure and on the other by compressor pressure. So unless your seals are completely gone, the odds of a runaway are small, but not zero.

First thing you want to do is to examine the turbo discharge passage and the intake manifold for wet oil.

If you have oil, try changing the air filter. It sounds odd, but it doesn't take much of an obstruction to cause the turbo to suck oily air through the crankcase vent.

Next, check the action of your EGR. I'm not familiar with your car, but there's some sort of modulation technology on every EGR-equipped car: early cars used pneumatic technology, later cars used electronics. EGR should be off at idle, off before you hit full throttle, and proportional to engine load in between. Too much EGR will massively increase soot formation. You can check this by T'ing a vacuum gauge with a long hose to the EGR supply line, and observing it as you drive.

Remove the turbo input hose and observe the compressor wheel...if you see breaks or chips, it's a sure sign that the bearings (and the seals) are shot. (it may also mean that there's a valve job in your future)

Another possibility is that the valve seals are bad. I don't have any suggestions for how to test that, except that a compression test won't do it. I suppose a leakdown test could, if you have a good ear.

charmalu · #5 01-27-2015, 09:38 AM

With the 400K mile estimate, and if the EGR has never been looked at,
I`ll place my bets that the hole into the intake manifold is plugged tight with soot and goop.
That EGR isn`t doing anything.

My 240D blew out some stuff on the shop floor that looks like your pictures, the other day also.

Charlie

eatont9999 · #6 01-27-2015, 10:27 AM

The EGR system was deleted and blocked off almost 3 years ago. It was one of the first things I did.

ROLLGUY · #7 01-27-2015, 10:29 AM

I hear that these turbos are very easy to rebuild. Around here the kit cost's only $50. Also, I believe a turbo engine can't (or won't) allow oil to get into the intake ports through the valve stem seals, because of the pressure in the manifold and intake tract. If anything, bad seals will cause more crankcase pressure from turbo boost getting through the seals and into the crankcase. However, it is a possibility that said crankcase pressure could force oil through bad exhaust stem seals and into the turbo and out the exhaust pipe. More likely in your case would just as you think: bad turbo seals. On my Mitsubishi, it had turbo seals (and bearings) so bad, that at idle it would produce a large blue cloud of smoke. After accelerating, the exhaust cleaned up. The oil pressure is higher than the boost pressure at idle, so the bad seals/bearings allowed much oil in the cold side of the turbo. After accelerating, there was enough boost pressure to hold back the majority of the oil that was meant to lubricate the bearings. I can only assume that the excess oil got into the hot side and out the tail pipe (same as in your case), as the entire back of my truck was oiled up until I replaced the turbo......Rich

eatont9999 · #8 01-27-2015, 10:30 AM

It's oil coming from the exhaust. I let the car idle this morning for 5 minutes and revved it 1/2 throttle for a second and it spat out more oil from the exhaust. I think the exhaust side seals are worn out. The car has had an increasing amount of white-grey smoke at idle in traffic. It can be seen during the day as well. It wafts up past the driver's window and is quite noticeable. A cloud is left behind during acceleration, too.

Mxfrank · #9 01-27-2015, 11:10 AM

Quote:

Originally Posted by ROLLGUY

I hear that these turbos are very easy to rebuild.

In theory, yes, as a practical matter, not a good idea. Turbo seals aren't seals in the o-ring sense. They're more like piston rings. If they're worn to the point they're blowing chunks, then the bearings may be shot as well, and that means there's a good chance than the compressor wheel has been damaged or the shaft is worn. Repair may require machine work to the capsule, replacement of the impeller or compressor and most important, balancing. You'll also need a few gadgets that aren't in your toolbox, like 16" snap ring pliers. So while it's true that the work is simple, there's plenty of room for complication.

eatont9999 · #10 01-27-2015, 11:29 AM

Quote:

Originally Posted by Mxfrank

In theory, yes, as a practical matter, not a good idea. Turbo seals aren't seals in the o-ring sense. They're more like piston rings. If they're worn to the point they're blowing chunks, then the bearings may be shot as well, and that means there's a good chance than the compressor wheel has been damaged or the shaft is worn. Repair may require machine work to the capsule, replacement of the impeller or compressor and most important, balancing. You'll also need a few gadgets that aren't in your toolbox, like 16" snap ring pliers. So while it's true that the work is simple, there's plenty of room for complication.

I understand all of these concepts. I have rebuilt turbos before. I will be buying a rebuild kit with everything needed. The shaft wear and the seal journal are a concern. If they turn out to be worn, I will need to replace them.

fahrvergnugen · #11 01-27-2015, 02:37 PM

According to Bergsma, you should plan replacing it above 200k.

eatont9999 · #12 01-30-2015, 05:03 PM

I had some help yesterday pulling a T3 off an 84 SD in the junk yard. It seems tight and I don't see any noticeable oil seeping past the seals. It should get me by until I can assess the possibility of rebuilding my K26. My grey SD is quite peppy, so if the T3 can't hold that reputation, I will definitely be looking for another K26.

eatont9999 · #13 01-30-2015, 05:09 PM

I didn't grab the exhaust or intake manifold as I reassured that the T3 will bolt on in place of the K26. Any experience with that, guys?

atypicalguy · #14 01-31-2015, 02:39 PM

I think the t3 compressor wheel was bigger in the SD turbos, or at least some of them. Kind of the opposite effect you're looking for, but better if planning a reworked pump.

Should bolt to same manifold but i have not done it.

atypicalguy · #15 01-31-2015, 02:40 PM

Adapter plates are cheap anyway.