turbo drain leak @ flange - PeachParts Mercedes-Benz Forum

JHZR2 · #1 05-01-2004, 03:06 PM

Hi,

Ive had a leak at my turbo drain flange for a long time. Ive replaced it once, had my mechanic do it twice. He got it down to a much smaller leak, but it still makes an oily mess on the underside of my engine. We have cleaned both surfaces completely, everything looks right. Id like to minimize the leak though.

I was thinking, what if I use a 'liquid gasket' like a permatex product, etc., on the outside of the entire mating area? This might provide exterior containment, provided it sticks. Do you think this would work? WHat would be the best product to use?

Thanks,

JMH

Fisherman · #2 05-02-2004, 10:22 AM

Oh man, if it is that is what I am dealing with right now...

First I (apparently or possibly) misdiagnosed a blown turbo seal. Turns out that this is very unlikely based on input from the not so local turbo shop.

I am now in the process of chasing my blowby as it appears to me that the oil is passing through tthe turbo/wastgate pressure hose and then leaking out the drain hole on the bottom of the wastegate.

Can you clarify this picture/leak location for me?
I have been putting a lot of grey matter to this issue and have some theories to bounce offf someone.

Upon closer inspection of your photo it looks like I see the pic clearer. I used a little shot of high temp rtv on my drain and it seemed to seal it weith no ill effects.

JHZR2 · #3 05-02-2004, 10:30 AM

I do have oil at the inlet to the turbo (where the u-tube mounts up), however, that is quite normal. This oil is not coming from the wastegate hose (mine is clear and clean), but rather from the actual oil return tube flange. There is oil flow that the turbo bearings actually are supported by. The oil comes into the turbo by a pressurized line from the oil filter, thru the top of the turbo. It flows through and has another line flanged on at the bottom. This is where my problem is. The inlet line is totally tight, the outlet line is leaky, and this is my problem.

It seems to me that you migfht have a lube oil leak that seeps into the turbo and flows out the wastegate hose somehow. I figure this because the oil film at my turbo inlet, which is apparently normal, doesnt cause junk in the wastegate hose, so it must be coming from somewhere else or in higher quantities.

JMH

TonyFromWestOz · #4 05-02-2004, 11:10 AM

As your turbo drain flange should not be under pressure (it is connected to drain back to the sump) these persistent leaks may be due to a restriction in the drain line, causing pressurisation of the flange.
Fix the blockage and you have fixed the leak.

Fisherman · #5 05-03-2004, 09:18 AM

Sorry yes after rereading your post I got where your problem is.

Actually while flushing my (temporary) turbo replacement I found that the flow through that bearing was not a simple pour it in pour it out thing even with kerosene. I think there is a certain amount of restriction in the bearing but you are right once it has passed thru the bearing it should flow down the tube and back into the oil sump wihtout pressure unless the oil sump is being affected by excesive pressure in the crankcase.

I used some high temp rtv on my flange (with a new gasket) and it did not leak. Could the mating sufaces have gotten scored or perhaps the flange on the return tube gotten bent slightly?

I learned a trick to removing the tube with the turbo in place. I took my dremel and ground off about a 1/4 inch of the tube "bell" where it slips over the lower tube. This allows you to pull it loose without removing the turbo much, much easier.

Fisherman · #6 12-24-2004, 03:43 PM

I have been chasing a few minor oil leaks this week and I have now come back to the wastegate. When hitting a hill hard i.e. full throttle when I stop there is oil dripping out of the wastegate drain hole (if that is what the hole is for) that is just on the exhaust manifold side of the wastegate coupling.
I took the snap ring out of this turbo wastegate last summer and could not see any reason that it should be allowing oil to pass from the turbo boost hose thru the wastegate diaphragm but that is all I can figure.

Does anyone have any ideas? I am stumped on this one.
BTW - Yes, I have some blowby but not what I would call excessive.

This is my 81 300SD, it is just pissing me off now!

I'm thinking the next move is to pull apart the wastegate diaphragm and use a little high temp RTV on the surfaces and then reseal it. Why would I get so much oil here though? I mean it can leave a small puddle if I stop for 5 minutes after climbing a hill.