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LUVMBDiesels · #5 09-16-2007, 10:06 PM

Do you know the history of the car? When was it last run? Does the owner know what happened to make it not start or did he buy it that way?

Did you change the secondary fuel filter as well as the primary?
The secondary looks like a small oil filter near the injection pump.

Does the '81 240D have an oil reservoir on the injection pump? If so make sure that it is filled. I am not sure if this year has the pump lubricated from inside the engine or not.

Next I would disconnect the line from the lift pump (fuel pump) to the injection pump and make sure that it is pulling up enough fuel.

I would also try this, disconnect both rubber fuel lines from the long metal lines going back to the tank and insert them into a jug in which you have poured two cans of Diesel Purge. I would then pull the remove the injectors from the head but reconnect them to both the hard and soft lines. Then crank the starter until you have run through most of the DP. This might loosen up the internals of the injection pump. Plus you will be able to see if the injectors start popping.

I would also pour Marvel Mystery Oil into the cylinders to see if that helps with the compression. If the car has sat for a long time the rings could be rusted and stuck. I had to do the MMO treatment a few times before my engine regained its compression. Let it sit with the oil overnight.

Since you are on the forum, try some searches using google advanced search. Put mercedesshop.com in the domain box and look at Diesel Purge, Injection Pump, Pull start. etc

Good luck