Fuel column “leak down” & Injection Pump element check valves - replacement procedure
 

I have been reading through the archives regarding replacement of the seals in the injection pump delivery elements. Steve Brotherton has made several postings regarding the symptoms related to faulty check valves seals, but there is very little information as to how to actually replace them.

In one posting there is a reference to a special socket to torque them down. In another posting there was a statement that the elements cannot be removed (except by a shop) from pumps that have "external fuel correction" capabilities.

My car is a 1984 300D -- do these pumps have external fuel correction? Is there really need for special socket to torque them down? If so, where could I obtain or rent one?

Has anyone actually done this themselves? If you could please post some helpful hints on how to do it, I would greatly appreciate it!

Thanks in advance!

RTH

External fuel correction = electronic control. You don't have it.

There are two nuts on the injection pipe at the IP -- the top one holds the line on the pressure valve assembly and the other on is the nut for the pressure valve holder. Take the line off, then unscres the pressure valve holder. The seal is an o-ring at the bottom and a copper ring. Have a care to get the bits all back in correctly, and oil or coat the threads with vasoline before replacing the pressure valve holder -- the torque spec is for lubricated threads, not dry threads. Clean everything VERY carefully before dissasembly and again before replacement -- grit or dirt here will cause running problems such as leaking pressure valves (no injection at idle) or sticking injectors. Not fun, nor cheap.

The later pumps use a multi-spline instead of a nut on the pressure valve holders that takes the special wrench. Otherwise much the same.

Later 617 pumps and 601/602/603 pumps have a locking bracket that must be removed to torque or remove the pressure valve holder. 615 pumps have a clamp between the holders to prevent them from rotating.

Peter