Parrot of Doom
MB Enthusiast
Most fuel leaks on the OM606 engine happen around the fuel pump, specifically the plastic fuel lines between the pump and the two fuel filters. These, while a bit inaccessible, are generally a quick and easy job to replace.
Tools:
Mercedes splined tool part no - 617 589 01 09 00
6 x copper seal (7f)
6 x o-ring (7h)
Sockets, torque wrench, torx bits, extensions, etc
Delivery valve schematic:
http://homepage.ntlworld.com/tom.jeffs4/car stuff/merc tech/diesel delivery reseal-1-1.pdf
The fuel leak we fixed today was on the other side of the pump - the injector side. This is where fuel is pumped out at high pressure, down hard metal lines, into the injectors, and thus into the engine. The leak was at the 6 valves on top of the pump (1 valve for each cylinder). There are 6 o-rings (these are the source of the leaks) and 6 crush washers to replace. To access these valves, the intake manifold must be removed, as well as the washer bottle and all 6 injector lines. Its probably not a job for an amateur DIYer like myself, which is why I was very glad to have my mate with me, who is much more experienced in these matters than I am. Its a good idea to have 2 people on this job anyway, since a spare pair of hands is invaluable for catching hold of loose springs, holding clamps, etc.
1) Remove washer bottle
1 bolt holds my bottle in place. Remove that, and pull the bottle to the front of the car - it will unclip itself from a small bracket. Remove any connectors on the top, and put it out of harm's way (I left it resting on the +ve battery terminal).
2) Remove intake manifold.
Full instructions can be found in the EGR cleaning thread. Essentially theres 1 bolt accessed from above, this unclamps the small pipe that enters the EGR valve to the back of the engine. Another bolt below (allen IIRC) holds 2 aircon pipes to a clamp, said clamp also is bolted onto the chassis. There are 12 torx bolts on the top of the manifold screwed into the head.
Once these are all removed, the intake manifold should come completely clear.
3) Remove injector lines
The 6 injector lines must be removed from the pump, and the injectors. This is easy enough, just a normal spanner can be used. Unscrew each line, its easier to start with line 6 (rearmost cylinder) and work down to line 1. As you unscrew each line, take care not to mix them up.
A simple way to avoid mixing them up is just to leave each line hanging in the relevant injector well. Another tip is to take a photograph of the arrangement, or you could tie a small label on each one.
Once you've removed all 6 lines, you should be looking at this:
You can see we've grouped 4 injector lines together on the right of the pump, the other 2 are at the left of the pump out of shot. If you look closely, you can see diesel welling up at the top of each delivery valve (its blue).
4) Remove splined collars
Each delivery valve is held in place by a splined collar. This collar is designed to stop the delivery valve from moving once it has been torqued to the fuel pump - if this collar wasn't there, then once you put the injector line on the valve and began tightening it, the delivery valve would start rotating in sympathy.
There are 6 collars, held in position by 3 bolts. Remove all 3 bolts. The collars will be stuck to the head with age and grime (and diesel). Get a flat bladed screwdriver and bend it 90' in a vice - this gives you a nice lever to get them up. Work them back and forth, they'll start moving. Then just lift them off.
From the picture above you can see the installation order - collars 1, 3, 5 are first on, followed by 2, 4, 6. They overlap.
Tools:
Mercedes splined tool part no - 617 589 01 09 00
6 x copper seal (7f)
6 x o-ring (7h)
Sockets, torque wrench, torx bits, extensions, etc
Delivery valve schematic:
http://homepage.ntlworld.com/tom.jeffs4/car stuff/merc tech/diesel delivery reseal-1-1.pdf
The fuel leak we fixed today was on the other side of the pump - the injector side. This is where fuel is pumped out at high pressure, down hard metal lines, into the injectors, and thus into the engine. The leak was at the 6 valves on top of the pump (1 valve for each cylinder). There are 6 o-rings (these are the source of the leaks) and 6 crush washers to replace. To access these valves, the intake manifold must be removed, as well as the washer bottle and all 6 injector lines. Its probably not a job for an amateur DIYer like myself, which is why I was very glad to have my mate with me, who is much more experienced in these matters than I am. Its a good idea to have 2 people on this job anyway, since a spare pair of hands is invaluable for catching hold of loose springs, holding clamps, etc.
1) Remove washer bottle
1 bolt holds my bottle in place. Remove that, and pull the bottle to the front of the car - it will unclip itself from a small bracket. Remove any connectors on the top, and put it out of harm's way (I left it resting on the +ve battery terminal).
2) Remove intake manifold.
Full instructions can be found in the EGR cleaning thread. Essentially theres 1 bolt accessed from above, this unclamps the small pipe that enters the EGR valve to the back of the engine. Another bolt below (allen IIRC) holds 2 aircon pipes to a clamp, said clamp also is bolted onto the chassis. There are 12 torx bolts on the top of the manifold screwed into the head.
Once these are all removed, the intake manifold should come completely clear.
3) Remove injector lines
The 6 injector lines must be removed from the pump, and the injectors. This is easy enough, just a normal spanner can be used. Unscrew each line, its easier to start with line 6 (rearmost cylinder) and work down to line 1. As you unscrew each line, take care not to mix them up.
A simple way to avoid mixing them up is just to leave each line hanging in the relevant injector well. Another tip is to take a photograph of the arrangement, or you could tie a small label on each one.
Once you've removed all 6 lines, you should be looking at this:
You can see we've grouped 4 injector lines together on the right of the pump, the other 2 are at the left of the pump out of shot. If you look closely, you can see diesel welling up at the top of each delivery valve (its blue).
4) Remove splined collars
Each delivery valve is held in place by a splined collar. This collar is designed to stop the delivery valve from moving once it has been torqued to the fuel pump - if this collar wasn't there, then once you put the injector line on the valve and began tightening it, the delivery valve would start rotating in sympathy.
There are 6 collars, held in position by 3 bolts. Remove all 3 bolts. The collars will be stuck to the head with age and grime (and diesel). Get a flat bladed screwdriver and bend it 90' in a vice - this gives you a nice lever to get them up. Work them back and forth, they'll start moving. Then just lift them off.
From the picture above you can see the installation order - collars 1, 3, 5 are first on, followed by 2, 4, 6. They overlap.
