Opinion poll: '82 Mercedes OM617 prelim treatment?

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I've just acquired a 1982 Mercedes 300CD with the OM617 I-5 turbo diesel. Approx. 160K miles (odo stopped working not too long ago at 149K) with 15w40 oil changes at an import shop every 3-4K, according to the PO. Hadn't been driven in about a year until I acquired it this week, but was started at least once in that time. Unsure when the last OC was but, of course, oil is black.

I've inspected the car pretty thoroughly and taken it on several
From reading up on the old MB diesels they can get soot in the rings if not driven well or maintained perfectly, causing low compression and blow-by - I'm sure the maintenance has been more than adequate but wouldn't be sure that the PO ever used fuel treatments or really blew the cobwebs out of it. Before being retired from DD duty a few years ago its commute was about 30 mostly-highway miles, some short trips in the suburbs, and an occasional 175-mile jaunt on the interstate. I'm going to change the oil one way or another before setting off for home, but I'm curious what you BITOG'ers think I should do initially to de-mothball the engine and get it internally limbered up and cleaned up best. Normal fill from here on out will be Schaeffer's 9000 5w40 at 6-10K OCI depending on oil performance (maybe do UOA) and driving conditions over the OCI.

1: Cost effective 5w40 (Rotella, Delo, etc.?) with Seafoam right off the bat, and change again soon after I get home (approx. 500 mi.)
2. Same oil as above, but treat fuel with Seafoam, diesel treat, etc. instead of oil for the run home. (Then maybe run that OC to 1,000 mi. with Seafoam in the crankcase for the last half?)
3. Two or three 1-2K OCI's with afore-mentioned oil but not extra treatments.
4. Schaeffer's for 3-4K with Seafoam for the last 500 mi.
5. Begin my intended regimen now, no special treatment.

Other?

Also, what fuel treatment will be best initially, and as a periodic maintainer? I've liked the results I've seen with Seafoam but that was in gas vehicles and this is my first foray into diesel-dom.
 
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Fresh fuel and air filters should be the first item of business, and drain any water trap (I'm not super familiar with the old MB diesels specifically). Try to find some B5 biodiesel (Love's truck stops typically have it) and run a tank of that. You should probably change the fuel filter again after that tank, as the bio will knock anything loose that is hanging on in the fuel system. That should be all the fuel treatment you need. I'm not familiar with Schaeffer's, but any syn HDEO should be fine. I'm not a big fan of Seafoam.

These engines are stupid reliable, so unless something is broke I don't really see the need for fuel or oil additives; if something is broke, fix it instead of a band-aid.
 
When I first got my (now sold) '82 300D it had a fairly rough idle, but a couple oil changes with Mobil Delvac 1 5W40 and a new rack damper helped quite a bit, along with an eventual set of 5 rebuilt injectors. Unless your engine has had every seal in it replaced, be prepared for pretty serious leakage with synthetic oil, mine leaked a lot slower with dino 15W40.
 
I would add, when you change the fuel filter, filling it with a can of LiquiMoly Diesel Purge is also a great idea, that stuff also helped a lot. Chances are, your bad odometer is a loose plastic gear-there's instructions online (Diesel Giant comes to mind) on how to fix it.
 
Certainly, I'll be doing the other filters along with the OC. These have one clear, plastic fuel filter just before the primer pump, and one spin-on filter that mounts behind the PS pump. I assume the spin-on filter is all the water trap this system has. I'll keep the B5 fuel in mind.

I don't see evidence of much oil leakage on the engine so hopefully it won't gush with thinner syn in it. I'll check out the rack damper, valve adjustment, timing chain, etc. when I get it home to my shop, but hopefully it'll make 500 more gentle miles as it is.
I'd found mention of the diesel purge, but didn't dive into the details yet as it looked like something better left for after I got it home. So filling the new spin-on filter with it and just starting it up will do some good?
 
You knock the cobwebs out of one of these every time you drive it since it needs to be driven pretty hard just to avoid rolling roadblock status.
These are not fast cars. An '82 would be a W123, a point in its favor as this is a very good platform.
These are solid engines that shouldn't suffer any particular maladies. Turbo problems are rare.
There was no water trap on our four cylinder 123s, so I guess that Mercedes found this unnecessary.
There is some sort of weird vent in the tank which may have performed this function.
I'd be more worried about the coolant hoses and fuel lines than the drivetrain itself.
This car should otherwise make a 450 mile trip without any problems.
This is a car from the day when Mercedes could honestly claim that its products were engineered like no other car in the world. The cars of this era had no cheap Chinese parts and everything is about as good as it gets in any car from any maker.
Enjoy this classic old Benz sedan.
 
I would use regular 15-40 HDEO without anything in it. I would put a striction Rx in the fuel. Hot Shot is one product that you use once a year. This would free up and lubricate the injectors and top end. I would worry about opening a lot of leaks with syn oil at first.
 
Ditto on the design and build quality. The more I looked over and tweaked on the car the other day, the more it became obvious that it was designed to make it very sturdy and refined, yet generally simple and straightforward to work on. No excess of parts, a good compromise of optimum engineering that still retains some kind of serviceability - not the simplest car or the easiest to make duct-tape-and-baling-twine fixes to, but one that can be maintained well and hence go many, many miles.
 
Originally Posted By: fdcg27
You knock the cobwebs out of one of these every time you drive it since it needs to be driven pretty hard just to avoid rolling roadblock status.
These are not fast cars. An '82 would be a W123, a point in its favor as this is a very good platform.
These are solid engines that shouldn't suffer any particular maladies. Turbo problems are rare.
There was no water trap on our four cylinder 123s, so I guess that Mercedes found this unnecessary.
There is some sort of weird vent in the tank which may have performed this function.
I'd be more worried about the coolant hoses and fuel lines than the drivetrain itself.
This car should otherwise make a 450 mile trip without any problems.
This is a car from the day when Mercedes could honestly claim that its products were engineered like no other car in the world. The cars of this era had no cheap Chinese parts and everything is about as good as it gets in any car from any maker.
Enjoy this classic old Benz sedan.
Like most IDI diesels, the 123s do best when driven hard (when fully warmed up)-mine wasn't slow, it would comfortably bury the 85 MPH speedo, just took a while to get there. Other things to watch are old fuel lines (ULSD makes them leak if they haven't been replaced), and the vacuum system can be weird/leaky, causing vacuum shutoff & power lock malfunctions.
 
I did the same thing but 850 miles.
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Car had a half quart bottle of autozone 10w40 gas engine oil. I just ran the oil that was in it.

Fuel filter slurped something up when I was gunning it.

Brakes overheated.

Sorry Photobucket hates the internet.
 
Congrats on the diesel. I LOVE W123 cars, currently own and drive two, and think they are some of the best vehicles ever made.

If it were mine, this is what I'd do:

- Buy four gallons of Delo 400 15w-40, two gallons of Delo 5w-40 (you mentioned schaeffers which is GREAT oil and fine as well), and two Mann oil filters.
- Buy two new diesel prefilters, and two new secondary filters.
- Buy lengths of rubber or cloth braided fuel transfer line, and a length of the injector return lines that go between the injectors.
- Buy a can or two of LM Diesel Purge, and a bottle of Power Service white or similar diesel additive and cetane improver.
- Buy a gallon of Zerex G-05 coolant and a gallon of distilled water
- Get a quart of ATF or preferably MB spec (can be generic febi or similar fluid), plus a PS filter and a small siphon.
- Get a few quarts of Dexron ATF or Maxlife ATF.
- New air filter and filter housing standoffs if needed.
- New valve cover gasket, feeler gauges, and a big socket for the crank bolt.
- Synthetic 75w-90 diff fluid
- Contitech belts
- Brake fluid

1) Apply normal dose of power service fuel additive to the tank.
2) Drain radiator and refill with ~1 gallon of G-05 coolant.
3) Drive to warm car.
4) Change oil with Delo 15w-40 and filter. Drive car as needed for a week or so, try to get tank as empty as possible, but do not refill.
5) On next car work day, warm car to reasonable level.
6) Remove fuel lines at prefilter, remove secondary filter. Fill secondary with diesel purge. Plumb draw and return lines to a jar holding diesel purge, start warmed car. Allow car to run on diesel purge until consumed. Change oil with 15w-40, filter not necessary.
7) Install new fuel lines and new prefilter, purge air through hand pump (if it leaks, buy a new style replacement and install using crows foot wrench).
8) Replace air filter and rubber standoffs as needed. Verify fit of turbo U tube and rubber bushings.
9) Drain ATF through dipstick suction or drain bolt. Add same amount.
10) Suction PSF, replace filter, replace fluid.
11) Replace diff oil.
12) When car is sufficiently cool, drain radiator and install second gallon of G-05/distilled mix.
13) Drive to fueling station and refill tank with maintenance dose of Power Service.
14) On next work day when engine is fully COLD, check and adjust valve clearances and check timing chain wear.
15) Change belts
16) Lift front end, verify suspension parts that need attention (it is highly likely that something will)
17) Bleed brake fluid
18) Change to 5w-40 after maybe 1000 miles
etc.

Good luck. Ask questions and definitely post pictures of the car!!!!

PeachParts is also a good forum to discuss these cars.
 
Check if any belts are cutting into hoses such as power steering belt into oil cooler hose. If so, long term fix is replace left engine mount to raise engine. Short term, use anything to move hose away from belt like tie up with rag or zip ties.
 
What he said.

Valves need adjusted every 15K miles; not too bad a job. It's much easier with the special wrench set as the two adjusting wrenches are bent to clear the injection lines and the other one has a spacer to hold it the perfect height above the head to engage the valve spring cap. Valves may be either too tight or too loose; there's no pattern.

MB only approved two additives to fuel; Chevron Techron injector cleaner, and BioBor Diesel Doctor (biocide).

Since the dipstick tube runs all the way to the bottom of the pan, it's possible for an engine with excessive blowby on a hard run to
push all the oil out of the pan. This does not bode well for engine/turbo survival (don't ask...).

If the timing chain gets too loose and skips a tooth, the valves will hit the pistons and the camshaft will come out in pieces.

This car has the mono valve for heat instead of the previous servo; rebuild kit was easy to install and about $30 vs $500 for replacement servo.

Great car; not too bad to work on and parts availability was pretty good when I owned mine. It will do about 98 mph on level ground at full throttle.
 
I've ridden in this one a few times before and 70-75 on a hilly interstate never seemed to tax it greatly.

The money nor time is there to do all that before setting off for home, but I will be DD'ing the car and it's in good enough shape that it's absolutely worth maintaining and improving so all that will come before too many miles are accumulated. But all the advice is welcome - gives me a better gauge of what maintenance is most pertinent and where over-maintaining may be particularly prudent.

With the oil fill cap off there's really no pressure (cap doesn't dance around trying to jump off), just a wafting of oily vapor. That 15K valve interval is going to keep me on my toes - that's second only to my motorcycle's schedule!
 
Other then the overly strong pedal return spring, you can keep your foot down in any of these old Benz diesels and they'll never seem strained.
I could do the same sort of speeds with our old W123 240Ds and a passenger would have noticed no signs of struggle in the journey.
IIRC, the five cylinder three liter turbo makes all of 114 bhp, which isn't all that much to move the weight of a W123.
Still, these are very nice cars to drive and the diesel has a pleasant mechanical note at speed, even though it gently shakes the whole car at idle.
I notice that you've bought a coupe, which in the 123 is very attractive.
Have fun with this old-school Benz. I know that I would.
 
Gas pedal certainly takes effort to put down - thank goodness it has cruise control!

I believe the OM617.95 is 125 HP. On the low side for horsepower, but about as much torque (170
or 181, depending on where you look) as most current mid-size gas sedans of similar weight.

Yes, the W123 coupe lines are quite nice. The sun roof is a really nice option, too.

Bought? Who said I paid anything for it.
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And the serial number is 000001, build date 01/81 - supposedly the very first 300CD turbo. If not, it's the very first CD turbo of the '82 model year which only makes it the 778th one, nonetheless.
 
So you're saying that you got this nice old Benz for free?
If so, good for you and I need not express my envy.
Don't think it made 125 bhp either and any current four cylinder would eat it for lunch.
 
My 83 is rated for 120 HP per the hood sticker.

Its cruise control adds 8 MPH to the set speed so I don't use it that much. Suspect the capacitors are getting tired.
 
Yep. Ex-girlfriend's dad (from 8 years ago) contacted me saying if I came and got it, it was mine. His dad gave it to him when his Civic hybrid burned in '09, he DD'd it until he bought a new '14 Accord, and let the plates on the Merc go a year ago when it was stored in a secure storage lot. He's just not the type to keep a second car and tinker with it, and I suppose it made him feel better to see me have it and take care of it than go through the hassle of selling it to some of the kinds of... individuals, that would be most interested in an old, project-grade Mercedes in St. Louis.
 
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