You're saying the injectors nozzles should be like new if they've run 135K miles? I don't agree with that. Mine were in deplorable condition at 135K on a 1-owner well maintained example. 3 out of 5 were shooting a straight line of fuel and the remaining two weren't far behind. All had cupped, concave nozzles.



Henry

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1976 Mercedes-Benz 300D, Colorado Beige / Mahogany
www.hmclever.com

Did you do all the miles yourself?

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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.

No, got it in 2017 with 133K miles. 145K now. Very good original docs, most of the miles were put on in the late 70s and early 80s. Owner died in '01 or so and it went into storage until I got it from a family friend of his - it was in a sealed shipping container until they retrieved it in 2017, drained the gas tank and sold it me. The car is in excellent original condition, and I have no reason to think that poor maintenance caused premature deterioration of the injector nozzles.

-Henry

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1976 Mercedes-Benz 300D, Colorado Beige / Mahogany
www.hmclever.com

It's tough call. I called my mechanic, he said he has a machine that tests them, which he did, as I still have them out he invited me to bring them in so he could show me. The nozzles look flat, they all look pretty damned good.

Oh man, I would give a lot to know the maintenance history. The title trouble was almost a blessing in disguise as w/o that I likely wouldn't have interacted with the PO. As I mentioned, she said her father was a VW mechanic, "from the factory in Germany," I can only guess that means either factory trained or previous engineer of some sort at the factory. Their name is indeed German, and much about the car is in pretty good shape. The father owned the car for the first 20 years or so, and only passed away a few years ago. That's one reason she was so helpful with the title renewal issues, and they wanted her to jump through hoops. Wanted her mother's death certificate (they had proof of her father's death), inheritance distribution (she had not titled the car in her name after her mother's death), a letter from her 'personal representative' (poor man's notary, best I can tell) verifying that she releases interest. I sent her photos of my first trip (below). She said she was so happy to see her car having adventures in the world and that her father would be smiling that someone was restoring it.

So who knows, would a guy with the means and knowledge replace injectors at say, 80K? My car sounds a bit like you describe yours. The body has a few tiny marks but the doors all close with that lovely, solid thunk sound. Even the cruise control works.

OTOH, the tach does't work (it's on the list) or the clock, and the climate control is always hot. Vacuum is not good (definitely on the list).

But hey, working cruise control is like a miracle. Works very well, really useful on the long trips.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

Perhaps the nozzles were already replaced at some point. Or there's some other confounding factor. Interesting.

I guess I'd inspect them at 80K and see how they tested out. But I might wait until 100K? Hard to say.

I'm looking forward to getting my cruise control working again. I guess your cruise control isn't vacuum-powered, which mine is. Also interesting.

Henry

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1976 Mercedes-Benz 300D, Colorado Beige / Mahogany
www.hmclever.com

It might be. The vaccum issues are hard to figure. Sometimes the door locking works, other times not. Sometimes the engine will turn off right away, other times not. The cruise control mostly works well, I should amend that. About once a half hour it will suddenly cut out completely. As if you just took your foot off the pedal. I've gotten in the habit of being ready to use the foot immediately, is quicker than resetting the CC, but it will reset and work again just fine until the next drop off. I can only guess it suddenly loses vacuum in those episodes.

I haven't yet mentioned that another issue is my ignition key/st. wheel lock going south. One day I had a bit of trouble with the key, didn't think to immediatly pull the cylinder, that night I suffered the dreaded paperweight/key won't turn sydrome. I was in WA state, in a parking lot, with my mother. I called her an UBER, and started looking hard at what to do. Decided to tow, AAA asked what's up, and then said their policy is to first send a locksmith. Dude did his best, no dummy, had one of those vibrator thingies. Could not get it to turn. None of it sounded good, me 750 miles from my shop. It occured to me that Home Depot was still open, I figured that to buy a batt powered Makita angle grinder to destroy the st. wheel lock would be cheaper than paying a locksmith $500 (WAG) to pull it out. And I'd still have the tool.

Saints be praised, I pulled it off. Will install new stuff soon. The punchline is, for the brief spell I've driven it since, I hooked my mighty vac up to the igntion shut down line. Oh man, that engine shuts off right now when I squeeze the handle. I've GOT to improve vacuum.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

Car sounds like it needs just a detailed mainteance run. An assortment of the usual suspects. Time more than money.

Estimate a day or twos time to lubricate everything after the essential issues are dealt with. It is well worth the effort in my opinion. It also can bond the car to you. So may things return to what they were like when new.

You got caught by the magic ignition tumbler. Any sensation of it becoming an issue at all. Members should replace it right away. They are too well known to cause real grief otherwise.

Holy crap I was kicking myself hard. I knew that a dead tumbers were a big problem. I just didn't think it would happen that fast. I had my Makita 18 volt screwgun with me - two batts. So buying the grinder w/o batts wasn't too steep. I've been around tools long enough to know that grind/cutting (those .048 thick carborundum wheels) works a lot better on hardened steel that drill bits, hacksaw, etc. Trying to drill out the tumblers struck me as way tough. Would need a good corded drill and parhaps diamond bits. One bad move and you scar up your dash. Grinding from underneath wasn't easy, a couple of times I thought I was at a dead end but it worked.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

On you car it's done by a servo motor that's right next to the power steering pump. And cutting out is a sign of cruise ecu going bad (bad caps and cold solder joints I have a diy link if you want)



On a W123 with OM617a an engine driven vacuum pump does:
1. engine shutoff
2. brakes
3. central locking (no separate electric pump like in a w126)
4. automatic transmission shifting (VCV simulates vacuum so it's like in a gas engine)
5. egr
6. climate control pods


so as you see there is a huge potential for leaks


If you test your vacuum pump by itself it should be making minimum 15 inches of vacuum


I would start by testing other systems with a mityvac

Great info, thanks. I really want to get on top of the vacuum issues, I just needed to get to greater priorities.

What you say about the CC makes sense. The vacuum is too inconsistent to operate the CC as well as it works. I would like that DIY link. Won't get to it for a while. If it went completely south I'd proably get to it quicker.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

diagnostics:

https://sites.google.com/site/mbcruisecontrolrepair/home/diagnostics/1982-1995-electric-servo-cruise-control-diagnostics

repair of a cruise amp (half way through the first post is your model):

http://www.peachparts.com/shopforum/tech-help/313824-how-cruise-control-amp-repair-14-pin.html

same guy can also do it for you. his new website:

Cruise Control Repair

Here are mine. Your description of cupped, concave nozzles caught my eye. Mine don't seem to have any of that, but these are the first MB injectors I've seen. What do you think?

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

Mine were definitely worse looking. It's kinda hard to see from the lighting. My fingernail would easily get stuck on the lip of the cupping. Now that you have them out, pop-test them. If only you were in Atlanta, I'd lend you my pop tester.

-Henry

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1976 Mercedes-Benz 300D, Colorado Beige / Mahogany
www.hmclever.com

Thanks! Nah, Atlanta's a bit far.

I hitchhiked through Georgia in Dec. '73. Camped out at a rest stop. Maybe the starriest night I ever saw.

I'll take them to my buddy, pretty sure that's the sort of device he has. Will get a kick out of seeing it. He wants to keep me happy. If I ever get rich and famous I'm going to have him put in new seals on my SDL tranny. He wants to do it. Says he can stop all the leaks. Might do it myself someday. Whoa, big job.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

Do not waste the opportunity to inspect the glow plugs heating up with the injectors out. The tips should get really hot visually. If they do I would not put in a new set. As you would have no ideal on most acquisitions of the time they have been in service. They could have been replaced not that many miles ago for example. Also have a look for possible carbon buildup in the pre chambers. Many of the aquisitions have not seen highway service for years.

Of note was one poster on this thread mentioned that every thing he did seemed to make some difference. I have advocated going through the fuel system at least partially on any new acquisition for years. How extensive depends on your 0-60 times for the version you have.

At a minumim enough to reduce the chances of an issue while away from home. It is usually very cheap to do yourself. All my versions of 123s are on the faster side of most other similar ones I have driven. Especially the 240ds.

I have another bone to examine as well. I expect these engines to light off as soon as they start to turn over. If they do not something is not right. In reasonable temperatures of course. If they will not do this they are going to be harder to start in cold weather if you need that ability.

A road breakdown can be expected to become ever more expensive to deal with. Every year. Many mechanics have no working experience on these engines. Plus there are other factors that can impact the situation. You want to reduce the probability as much as you can yourself. Doing it all cost less than all the components of just one road breakdown. When far from home.

We are also driving cars that a wait for parts of even just a secondary filter or belt can take time. Mind things like your lift pump is bad. To me it is simply preventative maintenance on antique vehicles.

Our 77 N/A 300d even is not too bad for what it is. The 84 300d has passing ability like a gas car. Or at least feels that way to me. It does so well in that area I am almost positive that the whole system must be functioning like new. I call it just making certain that all components of the system are working well. Not a true restoration .Expected Zero to sixty times are well documented in the archives on each version.