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  #1  
Old 04-22-2021, 08:32 AM
Ten13
 
Join Date: Apr 2017
Location: Asheville, NC
Posts: 116
Need to run something by you re: oil leak vs consumption

Hey there, All - I hope this finds you well and healthy and for the most part, sane (normal disclaimers apply here).

I have an '81 300TD-T with about 215 *very* well-maintained & documented miles on the clock. It has always had it's typical and expected territory-marking oil drips from various points under the engine and transmission. Nothing excessive or worrisome. This car lived its entire life in the SF Bay Area of California, and a charmed life indeed. In December 2020, my family decided that CA was trying just a bit too hard to kill us all, what with the fires, smoke, cost of living, crime, cost of doing business blah blah blah, and moved 'back to bedrock'; Asheville, NC to be precise.

The car was shipped out here, sat for about a month and it was cold cold cold. After my first distance drive (Asheville to Atlanta, about 2hrs 45min on the highway), I parked the car in my business partner's driveway for the afternoon while we had a "high level corporate meeting" on his back deck, sharing Panamanian Geisha coffee and vintage cuban cigars. About four hours later, I went out to the car and noticed a sizeable puddle of engine oil under the car, which was nose-down by maybe 2 degrees. It all seemed to be coming from under the bell-housing area, but you know how these things are; it's hard to tell sometimes. The puddle (keeping in mind how far diesel engine oil spreads when it hits the pavement) was about 6" in diameter. I rolled the car down to a level spot in the driveway and checked the oil. It was down exactly 1qt, and I checked it and topped it off before embarking on the 150mi trip.

I brought the car to a specialist in Atlanta, and they pressure-washed and put it up on the rack and determined that yes, this was in fact mostly coming from the rear crankshaft seal. Knowing full well what this means, I topped it up and drove it home. It was down a full quart upon the end of those same 150 or so miles.

Since January, I have been monitoring. Some days, after driving around town or highway, it leaves nothing more than it ever did - a few random drips from here and there. Other days, it leaves slightly more behind (but never what it dropped that first day). I have since determined it is dripping from just to the right of the bell housing (as you face forward).

Using 100mi increments as a basis for analysis, I have found that:

100 miles of around-town driving = less than a 1/4qt of engine oil loss.
100 miles of mixed driving (town and short highway) = 1/2qt of engine oil loss.
100 miles of highway-only = 3/4qt+ of engine oil loss. More if it's hilly miles.

To me, this seems like not so much a rear crankshaft seal problem (which is seeping, I grant), but a problem with pressurized oil, and, based on the precise location of dripping, it's under the turbo area. There is engine oil on the bottom surfaces aft of the engine, and there is also oil spattered lightly on the tailgate, which could be coming from the exhaust, too, after highway driving.

What's confusing me is the variability of engine oil dripping on the driveway. I'm inclined to think that this is a compound issue of leak and added consumption. It all started once the car experienced its first actual winter and deep cold temps. Car now lives in the garage with a radiant-heated floor, but those first few months after moving, it had to be outside.

Any of you resident experts have any food for thought? What I don't want to do is assume it's the crankshaft seal exclusively, because the engine otherwise runs amazingly well and efficiently. A turbocharger rebuild wouldn't be an unwise choice regardless of oil problems, and even if an engine rebuild is deemed necessary to get to that crankshaft seal, the turbo would be rebuilt anyway.

Thanks, and be well!

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  #2  
Old 04-22-2021, 09:45 AM
t walgamuth's Avatar
dieselarchitect
 
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 38,613
Seems to few miles to indicate a main leak of this magnitude. I'd look around the turbo carefully. There is oil under pressure feeding the turbo bearings so there could be a leak related to that area. If so its a lot less work to pull the turbo instead of the engine. There is a drain back tube which is right under the turbo IIRC that drains oil back to the engine oil pan. It is very tricky to get installed so it does not leak.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #3  
Old 04-22-2021, 11:06 AM
Diseasel300's Avatar
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You definitely have more than just a rear main leak. A leak of that magnitude from the rear main would have a constant thin stream of oil draining out of the car when the engine is running to lose that quantity of oil that quickly.

How's your engine blow-by situation? It's possible you could be pushing oil out if the blow by is bad enough or the breather tube is blocked up.

Otherwise, check the turbo. If you've had a seal failure, you can lose oil surprisingly quickly. If you've got oil spraying out the tailpipe, it's on the turbine end and yes, it can wind up on the rear surfaces of the car if it's spraying out like that. It could also be your oil leak that you're seeing, possibly dripping from an exhaust joint or the downpipe (which runs right next to the bell housing).
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Old 04-22-2021, 08:42 PM
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I second this.

Quote:
Originally Posted by Diseasel300 View Post
You definitely have more than just a rear main leak. A leak of that magnitude from the rear main would have a constant thin stream of oil draining out of the car when the engine is running to lose that quantity of oil that quickly.

How's your engine blow-by situation? It's possible you could be pushing oil out if the blow by is bad enough or the breather tube is blocked up.

Otherwise, check the turbo. If you've had a seal failure, you can lose oil surprisingly quickly. If you've got oil spraying out the tailpipe, it's on the turbine end and yes, it can wind up on the rear surfaces of the car if it's spraying out like that. It could also be your oil leak that you're seeing, possibly dripping from an exhaust joint or the downpipe (which runs right next to the bell housing).
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1983 300D Midnight Blue
4 speed, W115 intake mani, non-EGR exhaust mani, KKK K26, 3 pc Euro bumpers, Lo-spec Euro headlights, AL129X, hubcaps, custom A/C

1987 300TD Smoke Silver
Euro headlights, thermostat relocation, coolant bypass mod, rebuilt Becker + Jehnert + Helix audio, OEM Oris roof boxes and surfboard racks, Euro towbar

1983 300TD Reed (Moss) Green / Dark Olive MB Tex Euro spec

1983 300TD Silver Blue / Blue cloth Euro spec, OM648 and 722.6, 15" hubcaps, W126 S2 brakes
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  #5  
Old 04-23-2021, 10:33 PM
vwnate1's Avatar
Diesel Dandy
 
Join Date: Nov 2005
Location: Sunny So. Cal. !
Posts: 7,717
OM617 Oil Weeps & Seeps

Underneath the air cleaner and turbo are both oil return to sump and oil mist venting pipes that have various O-Rings and grommets, so on and so forth .

Once I replaced all of that on my Coupe the oil usage dropped to almost nil even though the engine blows a bit of blue (oil) smoke .

I'd begin there, the lower oil return pipe is a very common culprit .
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1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #6  
Old 04-24-2021, 08:49 AM
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Join Date: Sep 2006
Location: Middle TN
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I've had 2 126 617 cars and a 123. Both 126s leaked oil from multiple places. The 123 is at a body shop for rust repair so I don't know yet.

The fix for the SDs was to take the engine down to essentially a long block and reseal everything. The gasket between the block and oil filter housing and the turbo drain pipe and the oil cooler lines were also addressed. Now, no more leaks and I won't have to mess with them for a long time - perhaps never.

edit: I hate fixing one part of a system to only have another fail soon after. Elring makes a gasket set for ~60 retail that has most of what's needed. I never had to deal with the rear main on these engines.
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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.
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  #7  
Old 04-24-2021, 09:07 AM
t walgamuth's Avatar
dieselarchitect
 
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 38,613
Rear main is engine out.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #8  
Old 04-24-2021, 09:44 AM
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Quote:
Originally Posted by t walgamuth View Post
Rear main is engine out.

I understand AND wouldn't like to be continually wondering how much oil was needed or whether the engine is suddenly going to be killed. I also park in some places whee I don't want to leave a puddle of oil.

That's a lot of oil to only be coming from one place. My point was that there are several places that are or will be soon leaking. He can get most with the engine in car or pull it and do all. The oil filter housing is a pita but even it can be done on jack stands in the gravel in the heat.
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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.
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  #9  
Old 04-25-2021, 11:58 AM
vwnate1's Avatar
Diesel Dandy
 
Join Date: Nov 2005
Location: Sunny So. Cal. !
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Question Rope Typ Main Seal

No way to use the old "Sneaky Pete" Chinese finger trap tool on these ? .

My 240D's oil filter to block gasket is failing, I'm waiting for the new gasket to arrive before taking it all apart .

Then of course I'll have to wash the entire underside of the car, whew, it's a mess .
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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #10  
Old 04-26-2021, 06:50 PM
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Quote:
Originally Posted by vwnate1 View Post
My 240D's oil filter to block gasket is failing, I'm waiting for the new gasket to arrive before taking it all apart .

Then of course I'll have to wash the entire underside of the car, whew, it's a mess .

Is there enough room on a 123? The 126 is a pita especially without a lift.
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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.
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  #11  
Old 04-26-2021, 10:09 PM
Ten13
 
Join Date: Apr 2017
Location: Asheville, NC
Posts: 116
Hey All - thanks for the discussion and tips. To answer the blow-by question early on: I would say it's 'minimal' - defined as a vibrating (not dancing) filler cap with hot engine at idle.

I will put the car up on the QuickJack (no jack stands for me) and have a more in-depth look-see. I really, really, really don't want to yank the engine, because I definitely suffer from the "while it's apart..." syndrome! But also because the engine really runs cool, smooth and powerfully.

There's probably no real harm in rebuilding the turbocharger, replacing the impeller shaft if worn, and addressing everything I can get to "while it's apart", and start with that.

Any grievances with the ************** rebuild kits? Not sure PP has everything at this point.

Took my car, with kids loaded up in the back seat, along the Blue Ridge Parkway today -- a road perfectly suited for the 300TD with it's 45mph speed limit and butter-smooth roads and perfectly banked sweepers.

Stay healthy, everyone - I appreciate all of what you have shared and asked here.
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Filmmaker, Dad, Citizen of the World in Asheville, NC
=== current vintage stable ===
'73 VW Thing, '09 BMW 328i Convertible, '07 Honda Ridgeline, '94 Chevy Step Van
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  #12  
Old 04-26-2021, 10:51 PM
vwnate1's Avatar
Diesel Dandy
 
Join Date: Nov 2005
Location: Sunny So. Cal. !
Posts: 7,717
Post Oil Canister Gasket & Quick Jacks

Yes, there's room but it'll be a serious P.I.A., I did it on my OM617 turbocharged engine a while back ~ I had to disconnect the oil cooler lines at the canister end (TIP : buy the set of really large, thin stubby open end metric wrenches @ Harbor Fright Co.) and the little bracket that holds said lines to the left engine mount, I wasn't able to loosen the banjo nut holding the flexible oil pressure gauge pipe so that was another PIA, you'll have to carefully scrape the old rock hard gasket off the alloy canister, the block is cast iron so I used aerosol starting fluid (Ether, be careful) to dry out the old gasket bits then used a steel bristled toothbrush (.99 Cent Store) to clean that HOSPITAL CLEAN ~ a goodly bit of oil pressure goes through there so I didn't trust anyone else to do a proper job .

I used a brand new single edge razor blade on the alloy canister surface .

I cleaned the left side of the engine before beginning and again after I was done, I didn't need to drain the sump .

Quick jacks fold so I cannot ever see going underneath any vehicle using them for support .

Once you see what happens when a car drops on a human head (maybe dailyrotten.com has some pics), you'll never trust cinder blocks nor folding / collapsible supports ever again .

I'm ASS-U-MEing the shorter OM616 will give me a little bit more working clearance .

Best of luck, let us know how it goes .
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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #13  
Old 04-26-2021, 11:35 PM
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Check oil cooler hoses carefully for leaking. Not likely but could result in an engine disaster if they are and on the verge of real failure.
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  #14  
Old 08-16-2021, 07:56 AM
Ten13
 
Join Date: Apr 2017
Location: Asheville, NC
Posts: 116
Hey All - a long-overdue update to my oil leak/consumption issue in the 81 300TD. Recall the excessive loss of oil over short interstate (about 150 miles = 1 qt oil) distances. Two MBZ specialist shops each said "rear main seal", so I did a more in-depth tracing of where the oil was coming from. It seemed to be (mostly) originating around the turbo assembly, and running down and eventually dripping from just to the right of the bell housing / torque converter vent area. While the rear main seal may be a contributing factor, it was not 100% of the time that a puddle would accumulate under the car when parked, or dripping was evident while idling. Oil residue under the car was mostly on the right side of the driveshaft, as well - more evidence that this was not main seal-related.

Faced with an engine overhaul, I decided to just drive the piss out of the car. I drove it to the eastern shore of maryland for mother's day weekend - 8+ hours of interstate each way. I'd stop and top up the oil every 150 or so miles, and restocked my supply when stopping for fuel. One gas station only had 5w-50 in non-synthetic. When I added that to my 150mi top-off, the problem simply stopped. I made it the rest of the way to maryland and then all the way back without adding oil (it was down about 1/2 quart, which seems like normal consumption) after about 700 miles. The car has been back & forth from Asheville to Atlanta with frequency - the same trip that revealed this problem in the first place, and no appreciable consumption or loss. It only leaves a few dime-size drips in the garage (as it probably has since new) these days.

Fuel economy is ~26-28 for all-highway driving, and it makes great power and less smoke.

Did running 5w-50 oil create higher pressure that freed up a check-valve in the oil system? Was it a stuck or occluded line that was causing excess oil to leak from the turbo housing, which accumulated more readily on highway trips? Not sure. The oil has since been changed with 15-w40, and everything continues to run like a top, if not better than ever. Oil pressure is about 1.0-1.5bar at hot idle, and immediately rises to 3.0bar with some throttle, under load or not.

I guess the lesson here is that the assessment of the two shops was based on a quick look, not an in-depth assessment. The car has been driving another 6,800 miles since the problem started, and has never run better during my ownership. These cars really do need lots of exercise!
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Filmmaker, Dad, Citizen of the World in Asheville, NC
=== current vintage stable ===
'73 VW Thing, '09 BMW 328i Convertible, '07 Honda Ridgeline, '94 Chevy Step Van
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  #15  
Old 08-16-2021, 08:41 AM
vwnate1's Avatar
Diesel Dandy
 
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Location: Sunny So. Cal. !
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Thumbs up

Good deal .

Why not clean the engine, replace the oil return O-Rings and *know* it's fixed ? .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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