Mercedes 240D 123.123 619
Finally, I got around to replacing the gasket
between the injection pump and the motor block.
What a massive amount of work to replace such a
small gasket! It seems that cars just were not
designed with servicing in mind.
I could not find the Hylomar Blue and, based on a
discussion in this group in the past, I picked
Aviation Permatex from a lot of others. It is
supposed not to harden and that should make it
more effective in the long term. What surprised
me is the width of this gasket and the width of
the metal-metal contact. In places it is only
3/16". I would think that a wider bearing surface
would give much more resistance to leaks.
Of course I had to remove the complete injector
pump, after disconnecting the vacuum line (just
pulling it off the pump), the two control rods,
and the eight fuel connections:
1 Below the hand pump - the fuel inlet from the
tank via the small transparent filter.
2 Right beside No. 1 - again below the hand pump -
is an outlet that goes up to the top of the main
3 This is the fuel outlet from the main filter
down to the front connection of the injection pump.
4 This one is the fuel return line that starts on
the engine side of the injection pump, goes to the
top of the main fuel filter and then attaches to
the return line that goes back to the tank.
5 The other four are the metal fuel lines to the
Lastly, I removed the three nuts and washers that
held the front of the pump to a bracket at the
front of the engine, and another three that fixed
a small bracket to the rear of the pump and to
the engine block. The pump then was removed,
with the rear end down to keep the oil from
running out the front. I placed it level on a
bench top and noticed the oil coming out the
front. That was the area where the gasket was to
be located and, to prevent any more oil mess, I
turned the pump with that end down and drained
about two cups of oil. I sure didn't want it
dribbling out after I had the gasket and cement in
The Permatex - Aviation comes in a 4 oz bottle
with very few instructions. Basically: "Apply to
thin film to each surface. Allow to air dry for a
few minutes before assembling." This was all that
applied to what I was doing. I went online and
came up with a PDF (
that gave far more instructions. What about
people who can't go online? Undoubtedly everyone
has noticed that the instructions in English on
all containers are getting less all the time, to
make room for the Spanish traslation. Another cost
of the illegal migrations? When will we learn?
The gasketting went smoothly but, when I had
everything reassembled, I had trouble starting the
engine. I had released the air on Line 3 at the
main fuel filter and, after the bubbles stopped, I
tightened the nut and went on to Line 4 where it
attaches to the main fuel filter. While doing the
manual pumping I noticed a stream of fuel heading
downwards. I had oscillated the plunger up and
down by about 1/4" on each stroke and I guess that
it is worn or defective. I set up two plastic
containers, one under the main fuel filter, and
the other below the injection pump and then
vigorously repeated the venting. When I was
finished the container around the main fuel filter
had about a cup of fuel and the other one had
about three. I tried a few times to start the
engine and it came very close at the last try. I
stopped and the battery is now recharging. It
seems like I am near the end.
What a ghastly, messy, stinking - especially in a
hot garage - and primitive process this is. Why
not a liquid-air separator valve attached to the
tops of lines 3 and 4 with the air line heading
into the air intake and the liquid heading into
the return line to the tank? Now that would be
civilization! :-) Anyone heard of such a gizmo?
Is it possible to buy the manual pump plunger
itself, or the washer that presumably attaches to it?
I want now to stop all the drips from the engine
and I noticed that there was a small leakage at
the corner of the cylinder head gasket - the left
front side. I tightened the nuts to the correct
torque and I suspect that the cover may be a
little distorted. The gasket is only a few years
old. I am thinking of removing the cover and
gasket to clean them up and then use the Permatex
at that corner, or possibly the complete gasket.
This sealant seems to have an alcohol base so I
doubt it would bother the plastic of the gasket.
I won't be able to identify other leaks until I
get the car to a radiator shop to have the engine
box and the outside of the radiator very clean.
Anyone know what this typically costs?