Project Smokey Wagon 2014! - Mostly just noob questions inside. W123 1985 300TD - Page 11 - PeachParts Mercedes-Benz Forum

Mxfrank · #**151** 03-20-2016, 04:11 PM

You're overlooking another potential source for oil at the turbo, and the most likely based on your list of problems. The inlet of the turbo connects to the engine breather tube. There's not much flowing through the breather under normal circumstances. But with a hole in the pan and/or leaky engine gaskets, the breather becomes another source of air for the turbo. Drawing air through the crankcase also means drawing oil.

The turbo produces only 1 bar of pressure at full scream. Nominal oil pressure is 3 bar according to the gauge, but probably peaks at close to 5. So if you were dependent on hydrostatic pressure to oppose leaks, you would have quite a mess. The shafts and seals are designed to float on a film of oil, which is why they may seem to be a loose fit.

WarTowels · #**152** 03-20-2016, 04:56 PM

Quote:

Originally Posted by Mxfrank

You're overlooking another potential source for oil at the turbo, and the most likely based on your list of problems. The inlet of the turbo connects to the engine breather tube. There's not much flowing through the breather under normal circumstances. But with a hole in the pan and/or leaky engine gaskets, the breather becomes another source of air for the turbo. Drawing air through the crankcase also means drawing oil.

The turbo produces only 1 bar of pressure at full scream. Nominal oil pressure is 3 bar according to the gauge, but probably peaks at close to 5. So if you were dependent on hydrostatic pressure to oppose leaks, you would have quite a mess. The shafts and seals are designed to float on a film of oil, which is why they may seem to be a loose fit.

Mxfrank, I like your thinking but I believe I did rule this out with my latest test.

After cleaning up the manifold and turbo and running the engine, I had the entire stock air system disconnected and/or blocked off.

I plugged the crank case ventilation tube and the turbo was sucking filter-less. In this scenario the only source of oil to the turbo would be the turbo's cooling oil. And yet, I still had visible oil on the inlet side and oil being ejected between the manifold and turbo.

(I also plugged the ARV vacuum connection.)

Would an W124 Garrett T3 bolt up to the W123? I read they used a slightly larger trim, I think. There's a really clean one on fleabay for a reasonable price. Depending on what needs replacing on my turbo it seems like it could be quite inexpensive or equivalent to picking up this lightly used turbo. The big differences here being I could sell my turbo to recoup some money and avoid the cleaning and rebuild process on my current turbo. I am *sure* it has some carbon build up in need of cleaning.

ROLLGUY · #**153** 03-20-2016, 06:26 PM

Quote:

Originally Posted by Mxfrank

The turbo produces only 1 bar of pressure at full scream. Nominal oil pressure is 3 bar according to the gauge, but probably peaks at close to 5. So if you were dependent on hydrostatic pressure to oppose leaks, you would have quite a mess. The shafts and seals are designed to float on a film of oil, which is why they may seem to be a loose fit.

I am aware of that, and know that any oil that gets past the seals and bearings has lost it's pressure. It is a matter of the oil taking the path of least resistance. At idle, the oil will want to go past the seal and bearings (less resistance than the oil drain), but any added pressure (boost) should cause the oil to take the path of least resistance, being the oil drain. That is just how I see it in my case (Mitsubishi), but may not cross over to the turbo on a 617. The 617 may have more oil volume and pressure going to the turbo than the Mits, and that might explain the larger volume of oil getting into the intake at boost. Either way, a turbo rebuild/replace is in order.

Mxfrank · #**154** 03-20-2016, 07:28 PM

Quote:

Originally Posted by ROLLGUY

At idle, the oil will want to go past the seal and bearings (less resistance than the oil drain), but any added pressure (boost) should cause the oil to take the path of least resistance, being the oil drain.

Interesting. I wonder what the pressure characteristics are at the shaft. The compressor generates low pressure in the inlet and high pressure at the outlet. The shaft is right in the middle of the involute, which I would expect to be a low pressure area, but I could be wrong.

In this case, it looks as if the oil is coming back through the ARV. I bet if you remove the manifold and air plenum, you would find them drenched with oil, which makes it hard to identify the source.

WarTowels · #**155** 04-01-2016, 10:28 AM

Started taking the turbo center guts out but got stuck on one bolt. Trying to avoid buying Kent's tools to get it out, but we'll see.

Also started removing the oil pan and drain tube, only an hour or two in though.

I think I'm going to attempt to rebuild the turbo myself with a kit and see what happens.

vwnate1 · #**156** 04-02-2016, 09:01 AM

DO IT ! .

Only takes a few hours and makes a BIG improvement .

Ken's tools are handy but the picks he provides are near worthless ~ I tossed them in the trash .

It's important to be HOSPITAL CLEAN when doing this job and there's a lot of carbon crud in there you DO NOT want to get anywhere near the new bushings etc.

WarTowels · #**157** 04-02-2016, 03:21 PM

Haha, I shall!

Thanks for the encouragement! Just got some annoying news, my land lord is putting the place up for sale so I'm out at the end of the month. So one month to fix VIN up!

Anyone have any recommendations as far as rebuild kits? Merc source or fleabay?

WarTowels · #**158** 04-03-2016, 10:52 PM

Did some more work this weekend-

Oil pan's off-

Determined that I was shipped the correct replacement pan but the incorrect gasket. Will order a gasket soon so that will be good to get finished. I have the turbo drain pipe out and will be replacing all three rubber bits with OEM.

Turbo guts removed!

Both wheels appear to be in excellent shape with no pitting or chipping. There is zero shaft play from what I can tell. Everything exhaust forward had a predictable thin layer of oil sprayed all over.

Peeking into the intake manifold you can see it's pretty oily, but it's not absurdly bad. Anything easy I can do about this while I'm here?

I need to do some research on the disassembly of the turbo and start that, figure out what needs replacing. Hoping just a basic kit will do me, depending on the wear I find inside. Cheers.

WarTowels · #**159** 04-04-2016, 08:55 PM

Bunch of new parts ordered- correct oil pan gasket (hopefully), new oil pan drain plug and gasket, oil to turbo charger gasket and a few replacement oil pan bolts are two of them became slightly rounded. Went with OEM for everything but the oil pan gasket- figured if it's not the OEM oil pan why bother. OEM one seeped well enough =)

vwnate1 · #**160** 04-05-2016, 08:03 AM

Victor is the OEM gasket maker and I find it very unusual for this gasket to ever weep or seep , I rarely have to change them although the oil pan pixies often seem to scrape the lower sump until it's paper thin and weeping....

WarTowels · #**161** 04-05-2016, 09:41 AM

Oh Cool, then I did get an OEM one =)

Also ordered up a rebuild kit for the Garrett T3 so that should be along in a few days and I'll begin cleaning up everything today.

ROLLGUY · #**162** 04-05-2016, 10:53 AM

Quote:

Originally Posted by WarTowels

Oh Cool, then I did get an OEM one =)

Also ordered up a rebuild kit for the Garrett T3 so that should be along in a few days and I'll begin cleaning up everything today.

I have the non-ARV cold side cleaned up and ready to ship

WarTowels · #**163** 04-05-2016, 11:11 AM

^PM'd.

Also ordered up some replacement bolts for the turbo and the o-rings for the turbo to air manifold coupler. Hopefully no more oil sprays out of there when this is all done!

Looking forward to taking the turbo guts apart more tonight, based on the condition observed thus far I'm hopeful there turbine shaft won't be worn.

vwnate1 · #**164** 04-05-2016, 04:35 PM

Rich ;

I know little about these and was looking at one recently ~ are they better or just different ? .

I assume you mean to typ : non-ARB ? .

-Nate

Quote:

Originally Posted by ROLLGUY

I have the non-ARV cold side cleaned up and ready to ship

WarTowels · #**165** 04-05-2016, 04:47 PM

Quote:

Originally Posted by vwnate1

Rich ;

I know little about these and was looking at one recently ~ are they better or just different ? .

I assume you mean to typ : non-ARB ? .

-Nate

Nate,

It's ARV- Air Recirculation Valve.

Another user Gregs300CD describe it, "The ARV lets pressure from the intake manifold escape back to the inlet (decreasing IM pressure), allowing the EGR to pass more exhaust gas into the intake manifold."

The ARV (afaik) is on California models as an additional emissions system. I know it's on the 85' model and it might be on the others.

I'm on a quest to simplify my Merc and de-california it where possible so I'm going with the standard non-ARV cold side turbo. It's "better" to me because it's simpler and this late in the game probably isn't doing much in the way of emissions, also, I removed the EGR entirely...