Injector pump leak at fuel lines
 

My '87 300D Turbo has a fuel leak on the top of the injector pump where the high pressure fuel lines connect to the pump. The leak appears to be coming from next to the IP not at the actual line connection. I think that each line has an "O"-ring. Is the replacement of the O-rings a reasonable DIY project? Is it likely that the replacement of the O-rings will stop the leak at this location? Thanks for all comments and suggestions.

Yes and Yes.

You will need a 14 mm wrench for the lines, an allen (size long forgotten) for the pressure valve holder lock rings, new o-rings and new pressure valve seals -- the part numbers are listed somewhere in an old thread. You will also need some antisieze. A splined wrench for the pressure valve holders is required, there is no substitute.

Process:

Clean all the dirt off the IP and lines.

Remove injection lines at injectors and pump, lay aside (no need to actually remove from car).

Remove lock rings by taking the screw out for each pair. Likely to be stuck.

One by one, remove the pressure valve holders. They simply unscrews. Watch for the pressure spring that sits on top of the valve instert, it tends to stick in the holder, then drop on the floor.

Remove o-ring from holder, install new one, then use a pick to lift off the copper seal on top of the pressure valve body. Make sure everything is clean, then put a new seal on top, put the spring back in, and re-install the pressure valve holder.

When you have them all in, torque to 25 nM twice, then to 30 nM without loosening. If you don't have a torque wrench, this is a firm pull, no more.

Re-install injection lines, leaving the injector nut loose.

Crank engine until all the air is out of the injection lines.

Tighten injector nuts and start car.

Caveats:

No grit in the IP, make sure EVERYTHING stays perfectly clean. DO NOT pull the sleeves out of the IP if they get dirty, use some carb or brake cleaner to blast the dirt off!

Don't loose the spring inside the pressure valve holder!

If you don't get the torque correct, the seals will leak, causing running troubles but no other damage: Hard knock and rough idle with no smoke, but engine runs fine at high rpm indicates leaking seals. Just retorque the affected holder, should fix it. At worst, you will need another seal

If you can lay your hands on the spline socket, this is easy.

Peter

Thanks
 

Thanks psfred for the prompt and detailed reply. I may tackle this project with your good feedback. Thanks

I got a very good deal on the 300D because the pressure valve seals were leaking on three cylinders. Best $8.16 I ever spent on car parts....

Peter

I plan on doing this repair myself soon. I did a search and found the part numbers for the correct O-rings (017 997 41 48) and Copper seal rings (004 997 45 40) for my vehicle. The number given in an earlier post for the Spline Socket appears to be for the 27mm socket to remove the injector from the prechamber and not the tool for the removal of the delivery valve holder on top of the injection pump. Does anyone know the correct MB part number for the Spline Socket?

Found the answer to my own question. The MB part number for the spline socket is 617 589 01 09 00