I just replaced some fuel lines on my '79 300SD and when I pumped the hand pump to vent the fuel system, I had air coming out forever. I gave up on that and closed the hollow bolt on the main fuel filter, and continued pumping. My injection pump bypass valve never made an audible rattling sound. I had fuel coming out under the hand pump, so is my gasket shot and letting in air? Can I unscrew the hand pump and replace an o- ring or something? Should I replace the hand pump or is it normal for fuel to come out under it? My car seems to start and run fine.

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'79 300SD (340K),'71 VW Karmann Ghia conv.,Toyota '77/'88 Land Cruiser's

the primer leaks a little out of the top when I pump it too, so maybe my plunger is worn?

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'79 300SD (340K),'71 VW Karmann Ghia conv.,Toyota '77/'88 Land Cruiser's

The hand pumps are only around $15 each, including the copper washer. Please buy two and keep one for a spare -- it's cheap insurance. When these pumps leak, they can dramatically affect the performance of your diesel, BTDT . . .

Richard Easley
Waco, Texas

Your pumps are leaking and need to be replaced.

There have been some recent postings on trick to get the old one out. You may want to do a search. I personally did not find it that challenging, but my method certainly was not pretty and actually pretty crude. I just used a small set of vice grips to remove the old.

Good Luck

Thanks for the advice. I can't wait to see how much better it will run after I replace it. It has basically a big nut at the bottom, and it unscrews easily with a wrench. I think it has leaked for several years.

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'79 300SD (340K),'71 VW Karmann Ghia conv.,Toyota '77/'88 Land Cruiser's

Well, here is the outcome. I replaced my old screw open, white plastic, hand pump with the new Bosch, smaller, black, ready to push, replacement. It came with an adapter(which I did not use) because I believe it is used on all diesels. I got it from my dealer(part no. 000 090 88 50) because I was in a hurry($13.50 which is the same price as here except a slightly different part no.. PartsShops' no. is 000 090 00 50-$13.30). It was very easy to install, mainly because the new one requires a smaller 17 mm wrench, so I had plenty of room to turn. The old one was 24 mm. I was sure of getting all of the air out of the main fuel filter loosened bolt, tightened it while still pumping and listened for my injector pump to rattle which it did. I started the car and immediately heard a completely different sound when the engine turned over. I could hear the "choo", "choo", "choo", that I had not heard before. I was actually nervous something was wrong because it sounded so different. When it fired up I was amazed at how NICE the engine sounded. It purred like a kitten. I did not notice how before it was clanging and banging. I will feel much better about taking a trip now. My fuel mileage had dropped to 19 mpg. I expect to see a dramatic change in that for sure. I think it is idling a little fast so I may turn the idle down. Thanks for the help....One more note, I started the car this morning without plugging it in for the first time since I've had it, and the weather is below freezing.

[Edited by patsy on 12-04-2000 at 09:54 AM]