OK OK sorry to start a new thread. just delete it after I bought this car. (or not)
I checked out an '83 SD, silver, blue inside, no sunroof, interieur nice but driversseat ripped at the spot where you touch it when you get in, 167000 miles, odo tach clock windows air gauges everything works. doorlock dr side jammed. vacuum ok though. one key. not many dings, paint needs buffing or repainting if you are precize. no rust at all. car has been in storage 2 years.
engine looks new. as in, all the copper is new looking, the aluminium too, it just looks like a 70000 engine. little greasy oilpan, nothing major.
the only thing is:
it IDLES REALLY BAD! 5000 rpm and the whole car shakes of it. it shook the engine mounts to pulp. over 1000 rpm it's a lot more quiet. normal, yet loud. it looks like they did something with injector 3, the aluminium around it on the valve cover gasket shows scratches. I drove it and it has bad pickup but goes over 85. otherwise fine. WHAT IS THIS?? diesel gone bad from storage?

5k rpm.. it shouldnt idle that high or even run that high... post a thread asking for a carfax on that car with the vin handy.. it will tell you much

i could be alot of things, injectors, lack of valve adjustments,filters, ect. should you decide to buy it, change filters,adjust valves and run some dp through it.

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have no worries.....President Obama swears "If you like your gun, you can keep it

Do a compression check (if the owner will allow). If it checks out OK, I say buy it.

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1976 BMW 2002- 100k
1995 BMW 325i 175k
1984 Mercedes Benz 300D Turbo Diesel- 270,000 mi

1981 Mercedes Benz 240D- Estimated 300,000+ mi Returned to the earth

sorry I meant 500rpm (too low I know), I have no vin (I can get it though seller seems honest. for a seller.) and what is IP?)
I'm thinking about taking the risk I got him down from 3500 to 2200. if it's something simple like a flush or 500 miles flooring the car on B100 I would be pretty happy.
if a cylinder is ****ed i would not
a compression test, is that easy to perform by your 'random car sales smithville' ?? or maybe slightly special diesel?

I agree, you should get it checked out before you make an offer. The spec for idle speed is around 700 rpm, if I recall. I can get mine to idle smoothly down to about 550 rpm, but everything has to be perfect. There are several potential causes for the rough/slow idle, and there is no way of determining what's going on with out having it inspected. It's worth a couple of $100 to have it checked out if you are seriously considering it.

You really should try to find an independent benz shop in your area. I doubt you will get a good inspection by a general mechanic, because they don't know what to look for. BTW, a IP is an injection pump (the main fuel pump with the metal lines running to the fuel injectors.

didn't know injectionpump is usually abbreviated. excusez moi. yes, well maybe injectorpum-part #3 doesn't work I thought. and the rest of them do. that would explain rough idling (cylinder #3 not getting any...) yet reasonable smooth driving with bad pickup. so they tried to take out injector #3 with the wrong tools to have a look at it (hence the scrapyness on the valvecover around it) and didn't succeed. and know it runs like a tractor on butter
I guess I should take my time on this one. he won't go down on the 2200. I can replace a pump, I'm a little worried about timing it and air. and damage already done on cylinder #3 if it ran without fuel for a while. and timing a pump, that's always such a drag, having to get 5 fresh batteries before the engine finally decides to start working. bloody airbubbles. not to mention the thoughts about damage by turning it without lubrication.
indeed, an independent mercedesshop seems a good idea. but then again, there are such complete and utter fools presenting themselves as mechanics all over the world. and they usually get hired by the major companies... obviously I'd be one of them were I to present myself as a mechanic

FWIW, IP failures are not very common on these, it's more likely to be something else. Also, rebuilt IPs cost around $6-700, so you probably don't want to replace one unless you're pretty sure that's the problem.

maybe the old diesel gelled up one of the fuel lines? or a couple? or one injector is clogged up? pump seems unlikely to me too. but a couple of hundred for a test isn't really worth it I guess. it's a bit of a gamble this one. if you manually accelerate the engine and hold it at the point where the vibrating stops, (1000rpm or so) it'll start vibrating again a few seconds later. if you then pull it a little further, it will stop vibrating and start a little later again. that was odd.
but serious, that engine doesn't like idling! the rubbers it sits on are wasted. and it felt like it would explode when stopping. and even if you do get it fixed, would the damage be serious on the one cylinder that didn't get any? I'm sure it hasn't been driven much in the state it's in. I can get an IP at pull a part cheap, with 300k miles on it.

the injector probably isnt popping at the correct pressure or is coked, or the pre chamber ball is mia

yeah, it sat for 2 years he said. and before it ran fine according to him.
people talk a lot though, I never bought a car that didn't have an old man, housewife or doctor as previous owner. this one is the doctor version.
could be the injector that they must have tried to get out, whilst scraping the valve cover around it. my guess is their tool didn't fit so they 'machined it'. I have a set of 300k injectors, I could just go and make a deal with him. I put those in, it runs normal, I buy. who knows...
still my question about the damage done of running with no diesel remains.
price idea for buying as is?

would that be visible by taking off the return hoses (from the one that i think fails) to the other injectors and see if any diesel comes out of the disconnected hoses of the suspected injector? or will the diesel come out even harder when the injector is clogged?

to test the pop pressure youd have to either build a pop tester , buy one, or have an independent shop do it.

When the engine is running at normal temp try cracking the injector lines one at a time. If there is a significant rpm drop on each cyl then it's most likely the rack damper pin. You can adjust it sometimes and get the idle to smooth out. Sometimes they need to be replaced.
When I got my car it idled like a dead cyl but it was just the rack damper.