I am the new owner of a 1982 300TDT with 189,000 miles on it, purchased from a forum member. The car has very little rust, and a clean interior, with mostly documented maintenance history and miles.

When I got it, I noticed that there were tiny droplets of oil the rear of the car after being on the highway, not too bad. But over a few thousand miles it's gotten much worse, where it's practically covered in oil, and drinking a quart every 200 miles or so. I did a compression and leakdown test, and

1 340psi
2 365psi
3 375psi
4 370psi
5 320psi

I understand that first they should have done a valve adjustment, but based on what was found, doesn't matter, out of adjustment valves don't blow in lots and lots of oil, do they?

The leakdown test had smoke coming out of the oil fill, and not the exhaust, suggesting rings. They suggested removing the cylinder head for inspection.

Strangely though, I'm still getting 24 mpg reliably out of the car, which is higher than my last, didn't-burn-as-much-oil 300TDT.

I'm going to my trusty experienced diesel indy for a quote, but does anybody have any experience with something like this? New engines are more than I paid for the car, and a total rebuild looks difficult, just from a parts point of view. And quite expensive.

Any education on what to look out for, what kinds of questions to ask, etc. would be most appreciated.

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1982 300TD 300,??? miles, daily driver turned donor
1982 300TD, 184,000 miles, daily driver

I would first look for leaks before doing any major work. I had the same thing (tiny spots of oil, and a lot of it) on the rear of my old 300D, which was manila beige, evident after highway driving. I also had high oil usage during highway runs. It turns out I had several leaks that were at their worst when driving at high rpm over extended periods. The seal between the oil filter housing and block was one of the major leaks I had. In my case, fixing the leaks took care of the oil on the deck lid. If the car runs well otherwise, I don't know that I'd be too eager to spend a huge amount "fixing" it, as there isn't likely to be much return on your investment; I'd probably just drive it. If you parked the car on a nice clean driveway after driving it 2 hours on the highway, would it drip any oil?

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Christopher
'06 Mercedes E350 station wagon (silver/black)
'85 Mercedes 300D (black pearl/palomino)
'85 Mercedes 300SD (smoke silver/burgundy)
'79 Cadillac Sedan DeVille

'05 Toyota Camry (because always running is nice)

'85 Mercedes 300D sold back to orig. owner 8-1-06
'84 Volvo 264GL Diesel, owned 2000-2013

Maybe stuck rings. Has the car ever been vegged? Did it ever sit unused for a long period of time? There are various strategies for unsticking rings documented on here.

Or you might be due for an engine swap. Or you might just keep putting oil in it. That's what I did with my Suzuki with the bad valve seals.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I'll make sure to tell my indy that. This car has never seen veggie oil, but I have started running commercially produced B20 on it (so smooth!), which might have affected some of the rubber seals. I hadn't thought of that, it's very good to know.

If I run on the highway, it certainly drips oil. Not as much as my last one, but certainly dripping.

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1982 300TD 300,??? miles, daily driver turned donor
1982 300TD, 184,000 miles, daily driver

Stuck rings, the only things I've read about it is Miracle Oil, or something similarly named- taking off the injectors and letting some sit for awhile.

I don't mind putting in more oil, but it's going to get expensive quick. Fortunately I don't drive long distances every day.

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1982 300TD 300,??? miles, daily driver turned donor
1982 300TD, 184,000 miles, daily driver

oil from rings comes out the tailpipe.

If its on the back of the car it is an external leak of engine oil or if red tranny. I'd suspect valve cover seal, oil cooler lines, etc.

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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.

That is brilliant information. It's all over the back, so it' not coming out the tailpipe.

This would buy me time to try that Miracle Oil, among other things for those two cylinders that might have stuck rings.

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1982 300TD 300,??? miles, daily driver turned donor
1982 300TD, 184,000 miles, daily driver

I agree that it is not coming from inside the engine. It is a leak. Put the car on a lift and follow the well oiled trail forward to the leak site. Of course the belly pan may make it hard to follow.

I doubt that you have stuck rings, but if you did, a detergent additive in the oil would free them up, as it did on an old truck I once had.

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'97 E 300 D

If it's a leak, it should be easy to find. Clean the engine thoroughly and then start it up and see where the leakage is.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

This is going to be done, and very very soon, hopefully tomorrow or later this week.

I love this forum.

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1982 300TD 300,??? miles, daily driver turned donor
1982 300TD, 184,000 miles, daily driver

I use the "DIY" car wash, degrease, hot soap and water. Bring lots of quarters and she'll come out nice and clean. I put a little piece of plastic over the alternator but my cars are manual so maybe theres more to cover on the auto/turbo cars. The car wash makes a relatively fast an easy job of it.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

If you had stuck rings, you wouldn't have those compression numbers. Even if the engine does have excessive blowby, it shouldn't escape the PCV system. Look for a leak(s) as Tom W suggested. In addition to the valve cover, check the air filter drain for the oil separator and the turbo oil drain. Don't overlook the front and rear crank seals.

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'83 300D, 126K miles.

Tomorrow I go leak hunting.

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1982 300TD 300,??? miles, daily driver turned donor
1982 300TD, 184,000 miles, daily driver

I think what you're looking for is called Marvel Mystery Oil, sometimes abbreviated on the forums as MMO.

Good luck! I'm going to do this same thing to my spare engine.

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

This could also be a leaky SLS system.

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1983 W123 300TD US spec Turbo engine, with Euro bumpers and manual climate control, and manual transmission.