Turbo Oil Leak and New Custom Drain Hose - PeachParts Mercedes-Benz Forum

mach4 · #1 07-01-2017, 03:13 PM

Over time an oil leak I had developed got worse and worse. Originally I thought it was a valve cover gasket leak as I had just done a valve adjust, but as it got worse it was apparent it was coming more from the front of the engine. I really couldn't tell where it was coming from but my assumption was it was coming from the turbo seals. I pulled the turbo and manifolds and quickly determined the source of the leak - the drain tube cracked almost in half.

It's not a common problem for a turbo drain to crack, at least in the middle, so what caused the failure - one on the bolts on the turbo support bracket backed out allowing the turbo to flex a bit and cause the fatigue crack in the tube. I had a bit of a scare when I discovered what appeared to be a crack in the intake manifold. Did this crack due to vibration too? Fortunately closer examination showed it was just a casting anomaly.

Based on my original assumption, I ordered a turbo rebuild kit and began rebuilding my spare turbo. I haven't completely decided, but I think the original one is going back in. I also considered going with the federal manifolds and turbo setup, but that's too much work....though a test fit showed there was plenty of room for the lower mounting configuration (great to have options).

I decided this was a great time to do the turbo drain upgrade I've been planning. My oil lines are all stainless braided hose and AN fittings, as are the fuel lines and catch can hoses. Originally I made a two piece adapter for the drain tube (blue anodized one) but as my machining skills have improved I was able to make a one piece -10 adapter shown with the -6 catch can drain fittings.

The drain fitting can be installed with epoxy, JB Weld, RTV or possibly oil pan sealer - I used JBWeld.

The -10 fitting for the turbo end is a standard adapter readily available on eBay, speed shops and custom parts outlets.

Anyone that's ever removed the drain tube on a 617 upper oil pan will appreciate the simplicity of just removing a hose and never having to go through the pain and aggravation again!

mach4 · #2 07-01-2017, 03:37 PM

I'd like to offer my technique to the repertoire of methods that have been developed to remove the turbo drain tube from the engine - engine hoist and nylon strap.

It was in so tight it almost lifted the engine.

If you attempt this make sure you've got the strap restrained so it doesn't release violently and break something....or you.

BillGrissom · #3 07-01-2017, 04:27 PM

To clarify, your car sounds like 1985 CA model w/ turbo mounted higher (since you considered switching to "federal" manifolds. If so, your engine probably didn't have the "oil blow-by drain" stub in the top of the upper oil pan, but it appears the shiny fitting is over such a stub. Did you add the stub, or install an earlier oil pan?

This is a great idea and resourceful. My boss had a 300SD years ago which he stopped driving because he said the turbo oil drain tube had cracked (like yours), and his mechanic couldn't fix it. He knew I had a 300D and offered I could pick parts before the junkers hauled it off. I wondered why they couldn't just cut off the cracked section and insert hose, rather than scrap the whole car, but most mechanics aren't so resourceful. Fairly typical for people to give up too easy. A coworker scrapped a fairly new Chevy truck because dealer mechanics convinced him he had a failed head gasket and needed a used engine. I asked if he smelled anti-freeze in the winter and if his windshield fogged. Answer, "yes". Tried to convince him it was probably just a leaking heater core, to no avail.

mach4 · #4 07-01-2017, 05:14 PM

Quote:

Originally Posted by BillGrissom

To clarify, your car sounds like 1985 CA model w/ turbo mounted higher (since you considered switching to "federal" manifolds. If so, your engine probably didn't have the "oil blow-by drain" stub in the top of the upper oil pan, but it appears the shiny fitting is over such a stub. Did you add the stub, or install an earlier oil pan?

Good catch.... yes, the engine is from an '85 CA 300D. As part of my engine swap I got an upper oil pan from a 115 in order to gain some subframe clearance - it has a smooth bottom with no "waffle" castings like the later 617s and has the blow by drain nipple, which I use to drain the catch can.

mach4 · #5 07-15-2017, 02:29 PM

It's taken awhile, but I got the hose made up and have it mocked up on the "spare" engine.

Now it's just a matter of reinstalling the manifolds and turbo in the car.

It will be nice to eliminate one of the questionable pieces of German engineering on the car.