PeachParts Mercedes-Benz Forum - View Single Post

psfred · #2 03-12-2004, 08:42 PM

The seals on the pressure valve holders are shot. You need new pressure valve seals (copper) and 0-rings -- total cost for me a while back was $8.38 plus the cost of new injection line clips (they will bread when you unclip the lines)

You will also need a splined socket to fit the holders.

Procedure:

Remove injection lines on both ends -- you can just take the cap nuts loose and lay the entire assembly aside.

Remove the bolts that hold the lock rings down. Torx fasteners, if I remember correctly. Note order so you can put them back the same way.

Unscrew the pressure valve holders one at a time and lift off. Watch for the spring inside, it tends to stick in the holder and then drop out, and you MUST have it in there!. Lift the copper seal off the top of the pressure valve seat (a hooked scribe is nice here). Remove the old o-ring and put the new on on the holder, then screw it back down. Make sure the spring a seat are in place. Tighten finger tight for now.

When you have all six done, you must torque them all to 20 ft/lbs, then torque them all again to 20 ft/lbs without loosening, then to 25 ft/lbs, again without loosening. The seal is pretty critical, and a single stage torque will not usually seal them correctly.

Re install the loc rings, pre-loading them as much as you can to keep the holders tight. Use antisieze on the screws, the pump body is aluminum.

Replace the line clips and re-install the lines, leaving the injector end cap nut slightly loose.

Crank engine with you foot to the floor until only fuel comes out of the lines, then tighten, glow, and crank til it starts.

I'd do this on a hot engine -- it will start more easily.

Check the seals on the lift pump -- the suction line seals with an o-ring on the fitting, I think, and it can go bad. This results in all fhe fuel leaking out of the lift pump and sometimes from the filter on a slope, or in air getting pulled in (or both), making the car hard to start. Leaking pressure valve holder o-rings will make this worse.

Peter