1976 300d Question

Hey all, I just recently purchased a very nice MB, body, interior, and engine (supposedly) in excellent shape. Here is my dilemma, when I purchased it, (at auction) it was stated that it would just need a little TLC
since it has been sitting inside for 5 years. The owner died of cancer recently, but was going to have it running for the auction. I purchased it and messed with it yesterday to see if it would run. Replaced filters, primed fuel lines to injectors, replaced battery, etc. It has a 1800 dollar repair bill from 1994 in the glovebox with timing chain, valve guides, etc done at 92000 miles. I purchased it with 99500 on the odometer. Needless to say, with fuel at the injectors, it will not fire. I even went so far as to disconnect the glow plugs and shoot some starting fluid into the intake to see if it would fire. No luck! Then I placed my hand over the intake manifold, (disconnected the hose to the air cleaner, and it doesn't seem to suck the skin off my hand like other diesels I own. Is this a sign of bad rings? What vacuum should be on the intake manifold?
I removed the valve cover to insure all was fine there, but is it possible the timing could be off 180 degrees? Sorry for the long email, but wanted all to know what has been done to eliminate some of the obvious. It turns over fine, but no joy.
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"..repair bill from 1994 in the glovebox with timing chain, valve guides, etc done at 92000 miles. I purchased it with 99500 on the odometer."
So it must have run after the timing chain was replaced.
Yes, there should be some suction at the intake. There's probably a crank case breather hose connected to the intake that will relieve some of the suction.
Since you have the valve cover off:
Suggest you crack open the high pressure line to the injector for #1 cylinder (at the pump) and turn the engine by hand so you see (i) if there's fuel being sent to the injector and (ii) when that occurs, if both valves for #1 are shut (cam lobes at 1 o'clock as viewed from the front).
Then you can also check the synchronization of the cam to the crank. Just aft of the cam's chain sprocket is a collar which has a notch. Mid point on the driver's side of the front camshaft support is a cut groove. Turn the motor (not by the cam) to align the notch with the cut groove - that's TDC for the cam. Then read the scale on the crank's harmonic balancer - should be less than 5 degrees ATDC given the chain replacement job.
If you find all this to be OK then I suggest you check if the glow plugs are working and, if so, suggest you prime the fuel system again to ensure all the air has been expelled.
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Thanks T.G. for the response! This has me puzzled and makes me think that it is a timing issue and I will definately check on the suggestions that you mentioned. It especially worries me when it won't even fire on starting fluid (with the glow plugs inactivated) as well. Either it is way off on timing or there are all of a sudden issues with the bottom end. Thanks again!
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Starting fluid is BIG no-no on Mercedes engines. It washes the oil off the cylinder walls and you loose compression. The engine needs all the compression it can get to fire.
When this happens, we have to resort to 24V to get them started.

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I'd think that the stress to the connecting rods and crankshaft from the starting fluid's lighting off so early before the pistons reached top dead center would be a bigger concern with a diesel. (Especially in the case of a 350SDL.)
But setting that aside for a moment, wouldn't the engine have enough rotational momentum, after the starting fluid had been consumed, to get oil flowing onto the cylinder walls again while fuel was still being injected into the cylinders?

Simply cranking the engine with 12V (and without starting fluid) wouldn't restore oil to the cylinder walls adequately?
Geoff
--
"Many of the same people who cry 'No blood for oil!' also want higher
gas-mileage standards for cars. But higher mileage standards have
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writes:

Starting fluid is dangerous in a diesel that uses glow-plugs, which Benz does. Some large trucks have a provision to mount a can of ether with dedicated in-cab control.
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Holy cow TG! We all should pay you a salary! :-)
cp

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Okay all Update on the unit! It looks like all is in order with the valve train, and the timing on the timing chain as well. It would turn over fine but wouldn't start. I seen on another group that even though it is an automatic, it will start if pulled over 30 and then slipped into S. Well that worked well, and the engine would purr like a kitten. I had it running for about 10 minutes then decided to shut it off and restart. Once again, it will turn over but would not fire off. How fast are these engines supposed to turn over with the starter? It doesn't seem to turn over as fast as my powerstroke, but seems to be spinning faster than some of my diesel tractors, so that shouldn't be the problem, or is it? I do not have a tach so it is hard to know exactly how fast it is turning. Most folks say their engine is running with only one or two spins so I definately have an issue there. (I also loosened all the fuel lines and it is pumping fuel out on all the injectors, no air bubbles.) When it was running it seemed like it was not as responsive, so maybe the inj pump needs to be timed. HELP! Tim
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On 22 Nov 2005 06:02:37 -0800, against all advice, something

I'd replace the glow plugs. I had a roommate (from hell, but that's a different forum) with a diesel car. He needed a push start on a not infrequent basis. I suggested he change the glow plugs, and it started normally after that. The nice part is that they don't cost much, and you should probably swap them out anyway.
--




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Talk about a dedication to maintenance..
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Definately. This guy had a few cars that were his reason to live. Nice fellow with lots of friends as well. His vehicles were very nice!
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