Frankenstein '78/84 300D problems - Mercedes-Benz Forum

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post #1 of 1 (permalink) Old 01-31-2016, 01:38 PM Thread Starter
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Date registered: Jun 2010
Vehicle: 1974 240D, 1978 300D
Location: Winnsboro, TX
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Frankenstein '78/84 300D problems

'78 300D, the original engine (non turbo) overheated and did major damage, so I swapped it. The donor I chose was nothing short of extremely risky and dumb: An '84 turbo OM617 from Picknpull, with 450,000 on the odometer and a makeshift WVO system in the trunk. They didn't punch a hole in the oil pan like most of the cars there, which was nice, and it turned over, so I pulled it.

Off and on, the engine runs smooth and powerful, but most of the time it idles very choppy. If I try and take it for a drive, it will drive great for about 3 miles and then start loosing power, and after about 4 more miles of getting weaker and weaker, it dies. I have another spare engine which is lower mileage, and I might just swap it again because this is driving me insane. But first, maybe I'll ask for some advice.

What I've done since installing this engine:
-156k mile turbo injectors
-156k mile lift pump, new hand pump
-fuel filters, 3 times
-valve adjustment, 2 times
-compression test (was acceptable)
-cleaned tank strainer
-whole bottle of Biokleen in fuel (supposed to treat like 700 gallons)
-whole bottle of Dieselkleen in fuel
-bottle of Dieselkleen run straight into the lift pump, fully concentrated
-glow plugs (although it always starts right up)
-ALDA is unhooked, runs better without it, but still terrible
-bled fuel system by cracking injector lines, many times, with and without it running

As far as I can tell there's no air in the system, and it's getting enough fuel. Timing chain stretch? I'm kind of nervous about the timing chain job, more nervous than I am about swapping the engine again. IP timing (probably because of stretched chain)? Should I order rebuilt injectors? They are expensive relative to the free extra engine I have, but if it's highly likely that that will fix it, that's what I'd rather do. Another detail is that is runs worse the longer it runs. When it first starts up it idles really smooth, but after about half an hour of idling it's shaking the whole car side to side. Sometimes, but not usually, the thing has enough power to rival my Nova, and it really takes you by surprise, so I'm not thinking it's a thoroughly worn out engine.

I'll update with any other details I come up with. Here's a video of it running, after idling for about 10 minutes:

Last edited by GolfClapperX; 01-31-2016 at 01:42 PM.
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