Pressure Valve Seal Replacement
This was done on a 1991 Mercedes 300D 5 cylinder 2.5L Turbo Diesel,
but this process should be the same on most Diesels.



gather parts and tools... recommend
the two special tools - the socket with the splines
and the crows foot for the injector lines... although
a good 14mm wrench would work fine.


before picture so I know for sure how it's supposed to
be... (trying to keep my track record up of having things
work, look like they did before and not have extra parts
left over when done. ;)

Note the Diesel fuel on the top of the pump... after
careful examination I noticed that fuel was leaking,
seeping actually, from the #3 line at the base.


looking down on pump


loosened injector lines to get them clear
shot showing the 1/4" drive ratchet with extension
and the special 14mm crowsfoot.


pulled the locking plate bolts off
injector lines off


pulled the lines for #1 & #2 


removed the lines in the back to give extra room
by the pump.


shot of the two special tools, roughly around 20 to 25 USD each
The spline tool might be available other then from the dealer,
but trying to do this job without it would result in 
damage.  Torque spec works out to about 25.8 Foot Pounds 
of Torque - 35NM.  Injector lines get around 7 ftlbs.


The locking plates off the pump.


note the protection for the fender... hood barely
clears carport roof...  :)


Disassembled pressure valve also showing the new
O-rings, springs and brass washers.  Cleaned everything
out with cotton swabs.  The special tools are shown again.


Closeup shot of the disassembled pressure valve.  Not
sure if it's visible but the original o-rings were quite
distorted and flattened out.  It was a good thing I
replaced all 5 valve part internals.


looking down into the top of the pump.

The hardest parts were getting it started again... and
getting the dirt off of my forearms...  Runs great
now, and no more smell of Diesel fuel leaking onto the
ground.

John Meister     
© September 13, 2003 
 Snohomish, Washington