W115 1976 240d Problems - Mercedes-Benz Forum

 
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post #1 of 7 (permalink) Old 01-15-2013, 09:34 PM Thread Starter
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Post W115 1976 240d Problems

I've adopted a 240d. I'm still unsure why. It seemed like a good idea. I will be updating with pictures as I clean her out and clean her up. Little odds and ends that are irking me here and there.

My questions are:
Does this model have any known Achilles' heels? The same way my old W140 has that faulty fuel injector harness, is there anything I should look at replacing?

Is there a .pdf of the factory service manual out there? I've searched high and low for a download and haven't come up with anything. I would like to find one for free, but all the routes i take end up in paying for it. I'll bite the bullet if need be, but Benzworld has yet to fail me for anything MB related.

The major issue I'm having is that it's spitting out white smoke and runs like absolute garbage.. I set the timing according to the placard on the radiator support (24 degrees BTDC) and I feel as if the problem has gotten worse. Am I doing something wrong? I had this issue with an '82 240d that came into my garage a while back and I think I recall setting the timing closer to 60 degrees BTDC and solving the problem. I figured I'd get some advice before tearing at it again.

Thanks!

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post #2 of 7 (permalink) Old 01-16-2013, 08:19 AM
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As always with a diesel it's about compression. Absolute 1st step is compression test.

"white" smoke can be anything from coolant to brake fluid to incompletely ignited fuel.
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post #3 of 7 (permalink) Old 01-16-2013, 09:34 AM
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the easiest way is to test for blowby , if it shoots like a locomotive , the engine is worn .you may have a bad diaphragm at the vacuum pump , see if there is motor oil in the plastic line that goes to intake . i cant imagine a diesel running at 60 deg btdc , how are you testing this ???? . there is a diaphragm at the injection pump , this can cause bad running / smoke . totaly shot injectors will do it , also a bad prechamber , remove the injectors , and see if ball in prechambers are there in place .
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post #4 of 7 (permalink) Old 01-16-2013, 08:06 PM Thread Starter
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Mike, agillot, i've managed to get it running smoothly (for a bit) after my dad and I managed to mess with the timing enough. it won't stay running for more than 30 seconds or so.
i did notice however that the diaphragm is torn at the back of the pump. is this why it doesn't stay running?
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post #5 of 7 (permalink) Old 01-17-2013, 05:43 AM
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The diaphragm at the back of the pump? Are you talking about the governor mechanism attached to the very rear of the injection pump?
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post #6 of 7 (permalink) Old 01-17-2013, 07:11 PM Thread Starter
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yes, that diaphragm. i also noticed some leaking from the fittings where the lines to cylinders 1 and 2 go to the pump, so i ordered a few parts from mercedes and they should be here monday.
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post #7 of 7 (permalink) Old 01-18-2013, 06:28 AM
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If the diaphragm of the governor is torn, your engine should rev high. It will probably smoke too, unless you open the air flap in the intake manifold.

See this topic:
http://www.benzworld.org/forums/vint...moke-220d.html
for the working of the pneumatic governor.

If you used the drip tube to time the diesel pump, you should renew the copper crush washer (#5 in the picture below) in the delivery valve holder.



O ring #2 should also be replaced if damaged.

The delivery valve holder should be torqued according to a special procedure: First 30 Nm, then loosen, again 30 Nm and loosen again, now 35 Nm.

Work clean, diesel pumps don't like dirt.

Bleed the fuel filter and the IP (red arrow, picture below)

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