240D starting - Mercedes-Benz Forum

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post #1 of 4 (permalink) Old 06-24-2008, 08:58 PM Thread Starter
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240D starting

I took my 75 240D off the road for a few days to do some maintenance. I started with a valve adjustment (ALL the valves were too tight!) and I also pulled the injectors to see how they looked while I was at it. They looked pretty bad, so I ordered new nozzles and left the injectors out until the new nozzles came. Ohhhh what a mistake... air all in the lines.

After lots of cranking I got fuel to the injectors (some fuel comes out when I loosen the nut holding the line to the injector), but the engine is still not starting. It will on occasion fire a cylinder or two, but not much, and no smoke from the pipe.

I guess there are really only two possible problems. Fuel or air. What should I do? Is it possible I adjusted the valves badly? Do I still have some air in the lines/injectors/IP/somewhere else? Does it matter which side you hook the return lines to on the injectors? Should there be a few air bubbles in the clearish (return?) line from the IP to the top of the fuel filter?

Gah... Out of ideas.
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post #2 of 4 (permalink) Old 06-26-2008, 07:13 AM
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If you crack all the injector lines loose at the injectors and crank until fuel comes out, this should bleed all the injectors. If you can't get fuel, or just want to make sure all air is out, loosen the bleeder on top of the fuel filter and pump the primer pump on the side of the injection pump till only fuel and no air comes out of the bleeder. Then you can crack the lines again at the injectors and crank again to fuel comes out.

Another thought: Are you sure the glow plugs are working properly? If the connection of one of the connector wires got bad, or a glow plug happened to burn out (plugs in series), you won't get enough heat to start the engine. Might try checking all the plugs for continuity and cleaning all electrical connections.
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post #3 of 4 (permalink) Old 06-29-2008, 04:16 PM Thread Starter
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problem found

Time for an update!

I really did not think to check the glow plugs since the car was starting fine before, but that is the problem. The best plug of the bunch has 20 ohms of resistance. I will probably retrofit with the newer pencil style plugs.

Ill post again later with the result.

With the plugs out, I can also confirm that the new nozzles I put in are all spraying, so that was not the problem.

Thanks for the suggestions!
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post #4 of 4 (permalink) Old 07-13-2008, 12:50 PM Thread Starter
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Got it started

After I got the new plugs in it still would not start. I thought there must still be air in the lines. My car has a WVO conversion, and there was a valve for controlling the fuel return flow. It was set to loop back to the IP, which means the air was being recirculated. I switched that and primed the IP again to get air out. I then pulled the glow plugs so there would be no compression in the engine and the starter could turn fast and not burn up. Cranked on it a few minutes with the injector lines cracked a little. Put glow plugs back in and it fired right up.

Thanks for the help!
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