Hi ,I'm new to this site.I have a very hard starting benz.It also idles very rough.I changed all flters & bled all lines.It seems like theres not enough oil at the pump as it fires and then dies .Does the vacum pump pull fuel into the injecter pump?.I also put in new glow plugs.My question is what next.The car does use lots of oil and smoke some.The car was sitting in storage for some time.It shows 56,000 miles but the speedometer is acting funny so I don't know how acurate it is .If anyone is familiar with this model I would gladly try anything.Thank You GaryH

If it uses oil, likely it has serious cylinder wear -- that model was known for soft cylinder liners in the original design and hence pre-mature wear (they normally run several hundred thousand miles before giving trouble.).

You should do a compression test and leakdown test to determine what is going on -- worn out valve guides will do the same thing (oil goes past the valve stem and gets burned, and the valves are worn out and don't seal).

Check valve clearance -- these have manually adjusted valves, and if ignored, they close up and the intakes will stay partially open cold, makes them hard to start and rough. Leave them a bit wide and re-check, as carbon on the valve stems can also hold them open, once adjusted, the carbon wears off and they will go tight again.

Replace the hoses between the supply line and the lift (hand) pump -- it's likely rotten and allowing air in. If the hand pump leaks fuel when you operate it, replace it, it's also leaking air in.

If you get copious clouds of unburned diesel while attempting to start, the fuel system is OK -- if not, you have a leak. Once fixed, it will take a bit to get all the air out of the pump, so run it a while.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

High oil consumption on this model could also be due to a broken/torn diaphram in the vacuum pump, which puts engine oil up to the intake and then thru the combustion side of the engine. This is not a difficult repair if that is what the problem turns out to be.

The vacuum pump is used to operate the power brake booster, since diesels do not generate a lot of vacuum on their own.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

Thank you all for the great info I will check them all out and come back with the results Gary H

Hi It's me again Gary H.I have 2 lines coming off vacuum pump.1 goes to brakes the other goes to the air intake manifold and then to the injection pump.I feel like it has something to do with getting fuel to the pump I'm I right or not? Thank You

Gary, I do not believe the vacuum circuit has anything to do with the rough running etc. The pipe going to the manifold from the vaccum pump should have no oil in it if the vacuum pump diaphram is intact. That is what one person meant by stating it could be a source of the oil you are burning. Just disconnect it and see if there is any oil there. You could check the valves for clearance next as mentioned. That is important. It may or may not pay to run some concentrated diesel purge through the fuel system. Beyond that I would do a compression check and if good enough check the injectors out. Or you could loosen each injector nut in turn to determine if all cylinders appear to be firing equally. If you run across something bad and really expensve the 240 engine probably drops right in and is the cheapest solution. You do have fresh fuel in that car for starters?

How can I tell if I need to replace timing chain and all sprockets.where will the wear show.I'm rebuilding the Engine so this would be the time to repair it.If anyone has any thoughts please respond. Also I'm still trying to find the rubber part on the front engine limit stop.No one seems to know what it is.I can post a photo if interested.So far the oil use problem seems to be valve guides and seals.The pistons bore show about .30mm wear on top & about .02mm on bottom. They are very smooth and show no scratches of any kind.I will take to local auto machine shop to get opinion on what to replace and have them size and fit if necessary. Valves are burned bad and reflect low compression reading on 2 cylinders.Thank you for reading and all the interest.This is a great site.Gary H

Gary, if you're rebuilding the engine then it's cheap insurance to change the timing chain, tensioner and guides. Perhaps also the springs. Sprocket wear to me is an eyeball thing. If you know what the new sprocket is supposed to look like.... ....and your eyes may be different than mine.

Try Phil at this site for the front engine stop. Any parts guy is going to have to look at the microfiche then cross over to the computer for these old parts, by the way. Some (not Phil) are lazy. That CD I referenced earlier (also from Phil) has front engine stop installation and adjustment instructions, as well as great engine overhaul stuff. Send me a Private Message with your e-mail address and I can send you an Excel file I built which is a table of contents for the CD.

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daBenz - 1970 220D