’81 300SD injector pump hand prime pump replace?

Jun 08, 2005 1 Replies

Hi All: I have traced a hard start condition to what I think is the cause. The hand prime pump allows air into the fuel system. Today after the car had sat for 4-5 days I used the hand prime pump for about 20 strokes, could see air bubbles pushing through the clear plastic bleeder tubes between injectors. The hand pump was leaking fuel that spilled down the side of the engine. I then started the car, it fired right up so I feel this pump is the problem. Some posts point to this as a cause. My questions are: can it be done with the injector pump on the car? Can anyone give me a blow by blow of how it is done? Can you seal the existing pump or must you get a new one? Can I order this from any Bosh dealer instead of MB? Any help or opinions are always welcome. I have had great success here to solve other MB problems that haunted me for a long while.


The seal under the screw down handle is broken or is missing; it cannot be repaired or replaced.

One can buy a hand primer pump from most on-line M-B parts suppliers for about $20. It's a simple remove and replace process - use a wrench to unscrew the old leaking pump and install the new pump. There's a hex or octagonal configuration at the base of the pump for a wrench or just use a pipe wrench on the old one, but not the new one.

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