Wastegate oil leak... any thoughts? - PeachParts Mercedes-Benz Forum

Fisherman · #1 04-22-2004, 01:44 PM

Hi all,
On my way back from the SF Bay Area last night I developed two major oil leaks that I need to dive into. I was hoping someone else has pursued these same leaks and can give me an idea of what to look for while I'm diassembling. Both of these leaks started at the same time so I think they are related. The leaks also started after doing some light road racing through the mountains of Sonoma county.

I have one drip that has started in the middle of the body of the wastegate. It looks like it is a two part assemply and the oil is seeping out of the "ring" of metal on the exhaust side and then dripping down from there. When I pulled the boost tube and revved the car it started dripping a little oil (about a drop every 5 seconds). This leak is not too bad but concerned me and I stopped every 60 miles or so to check the oil level and make sure all was still functioning. Now here is the connundrum in this...

I thought that this was the only leak and that it was blowing back against the transmission housing and then leaking down but upon further inspection the whole back of the motor on the passenger side under cylinders 4 and 5 is just soaked ( I mean drowned like a river ran down it) with oil. This as it turns out is the major leak and I mean major. I used a quart every 100 miles and apologized everywhere I filled up with fuel.

I'm thinking this could be a head gasket or maybe I blew a turbo seal and that the oil is dumping into the manifold and then dripping/running out of the manifold gasket? I mean it looks like a lot of oil. No oil on the turbo itself.
Park for 5 minutes and you get a puddle of drops about 3 inches in diameter. Of course it does not all puddle but rather drips from 4 or 5 places on the cross member and off the back of the engine.

Question:
If I blew a seal on the pressure (fresh air) side of the turbo it would also cause oil to get into the boost tube to the wastegate wouldn't it potentially cause the affect of the oil dripping out of the wastegate?
if it is a turbo seal can you DIY a repair on this or is this just for the turbo shops to deal with? I have access to a '85 300D turbo that I could install.

I hope this makes sense. I'm looking at it sitting in the driveway and I have two puddles under it about 8 inches in diameter this morning. Lucky I made it home by 1 am I suppose.

psfred · #2 04-22-2004, 09:24 PM

Turbo seals are toast OR you have colossal blowby. Check the blowby, but I'd bet you have a dead turbo. If you have oil on the exhaust side of the turbo, it's for sure the seals.

Best bet is a cartridge (bearings, housing, seals, shaft, wheels). You unbolt your housings and bolt them onto the new cartridge.

The reason I say this is that usually by the time the seals get trashed, the bearings are gone, and it's much easier to replace the cartridge than attempt the bearings. A good turbo shop can advise better than I.

Check the valve cover gasket for cuts -- an amazing amount of oil will run out if the gasket is shot, especially if you have excessive blowby.

Peter

Fisherman · #3 04-22-2004, 10:38 PM

I'm gonna start pulling things apart this weekend and see what I can find. I donb't think it is blowby unless something went seriously wrong during the course of this trip. Engine still starts fine though and runs strong with no odd noises so I'm inclined to think turbo also. I still ran fine though all the way with good boost as far as I could tell.

Then again who knows? I was so tired by the time I got in the driveway that I should probably have parked a hundred miles short of home.

psfred · #4 04-22-2004, 11:37 PM

Take the filler cap off at idle. You'll know if the blowby is too high.....

Peter

Fisherman · #5 04-24-2004, 09:26 PM

Get this,
The turbo blew a seal on the output side (fresh air) and was half fuill of ol on this side. An interesting side effect of this blown seal was that the valve cover started leaking profusely out the bolt holes on the passenger side and the gasket itself.

Near as I cna figure the additional leak of the boost got into the intake exhaust manifold side and caused additional pressure to build within the crankcase. This in turn at speed could not be vented effectively to the cyclone. Therefore it tried to find its way out everywhere it could.

Wild discovery...

So I put in a turbo off an 85 300D (should be the same motor) but it has the vacuum thing on the front. When I first put it in there was virtually no boost although you could hear the turbo. I then disconnected the overboost changeover valve and voila I have boost.

The real bummer in all this... The old turbo (leaking as it was) gave me so much more power...

I need to find a rebuild or a good used one or that "cartridge"? Are they commonly available for these cars or is this a speciality item. I think I will go ahead and rebuild my old one and put it back in the car just for sh_ts and giggles.

Fisherman · #6 04-28-2004, 09:20 PM

Upon further inspecion the turbo seems ot be fine. I had diagnosed (incorrectly) that the shaft play up and down was the result of the seal blowing out and the bearing being bad. Well I was just informed by a turbo shop tha tthese garretts have floating bearings so up and down play is normal...

Sooooo... We start looking into the blowby issue. I swear it is not excessive but more than the 84 has.

i'm now considering that the valves may have reseated after I adjusted them and now they are too tight again givingme more blowby? This one is driving me nuts but I will find the solution...

psfred · #7 04-28-2004, 09:58 PM

Check to make sure the oil separator isn't clogged, too. If it is (or the o-rings are bad, or housing loose) the oil won't run back down into the crankcase. Ditto for a bad foot valve, as the blowby wil then blow oil up the tube and into the intake rather than draining it back.

Up and down play is minimal if palpable. If you can move the wheel at all axially, the bearings are shot. Side to side play should be less than 0.020". If you can move it a lot, the bearings are toast.

Peter

notlostmaybe · #8 04-28-2004, 10:54 PM

i just bought an '83 turbo with an oil leak like
you describe; below the turbo, 4&5th cylinder, spillng
on to the tranny. lots of fresh oil on an otherwise clean
engine. turns out that the blowby tube out of
the air cannister was not aligned with the pipe to the sump.
easy fix.
off subject, the turbo boost pressure was 19.5-20 and the
alda has never been adjusted. ran cool and very quick. turned
the boost down to 14.5, the lowest it would go and upped
the alda. not as quick.

don

Fisherman · #9 04-29-2004, 01:48 AM

I decided to chase the blowby a little more after runninga conversation wiht a turbo shop that informed me that my leak evidence although obvious that there is a leak my not be from the turbo.

This car only has 160K on the clock so I'm a little dubious of the turbo dying already.
No metal hitting metal in it. what do they say about a dead horse?

Peter,
I blew into the seperator return line and got bubble noises. I then applied light suctionvia my mouth and couldn't draw but hey, I'm not going to use this method for too much testing...
that was why i asked in either any earlier verions of thispost or another post about pressures for the backflow preventer there. I have a mity vac and could test it oput if I had an idea of perssures it should hold.
Already replaced all the gaskets from the turbo drain adn the seperator return tube. Funny, that's when all this started to manifest or is it that after celanign things up that's when I started to notice... one step at a time is all I can take anymore.