Trying to help a friends mom out. She has an 87 300d with a fuel leak on the top of the IP around the $3 injector line. After blowing the unit clean, letting the engine run for several minutes you start to see fule on the serrations where the fitting enters the pump. Seems to be only #4. Is this something I should tackle or send it to a dealer. I'm wondering if that piece threads out of the pump and maybe has a leaky seal at the base that could be replaced?

Should be an oring and a crush washer inside of the valve holder. Orings go bad. If you do one you usualy do all.

Is a lil bit technical. I believe you will need a special MB tool (socket) to remove the valve holder. MUST not distrub anything inside the holder (dont touch, twist or allow vavle element to fall over) or can mess up the claibration of the pump resulting in having to get it recalibrated on a Bocsh bench tester or replaced. Torque on my 606 is 30-35NM, should be similar on your 603.960.

Search here for "Delivery valves" or "Pressure valves" for your specific engine for more info.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Allison, I agree. It sounds like a classic delivery valve seal job. The 603 (PES pump IIRC) seems to be sensitive to ULSD.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!