After wondering why I had trouble starting my 1987 300TD on an incline, I discovered I had a major drip from the bottom of the injection pump. Furthermore, the top of the injection pump is damp as well where the injector lines meet. Is there a seal kit to fix this and is this a DIY job?


1987 300D 186Km
1987 300TD 196Km
2001 CLK 430 Convertible 32Km

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

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

The pump on my 603 is leaking as well, but from the emergency shut off lever.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

Mine too (leaking around the 'stop' lever)! Does anyone know how to fix this? It's not a major leak, but I hate having any sort of leak...

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1989 250TD Wagon 5-speed, 160,000mi ::: Dark gray metallic / black cloth
1984 190D-2.2 5-speed, 287,000mi ::: Silver-blue metallic / black MB-tex ::: SOLD

I followed psfred's procedure and the leaks stopped. However, I had a problem afterwards with the fuel line tubing going to the injectors. It seems, that I could not get some of them to seal on the injectors. Less than 10 miles after the pressure valve seals were replaced, the #2 fuel line tubing started leaking (squirting) on the top of the injector. I tried to tighten the the 14 mm nut but no luck. So far, I had to replace the #1, #2 and #4 fuel line tubing at about $32 a piece. I imagine, I will have to replace the rest at some time soon. Any similar experience out there?

Thanks,

1987 300 TD 198Km
1987 300D 185Km
2004 CLK 500 Convertible 200m

Replace all the plastic clips on the injection lines, otherwise the vibration will cause the line to fail at the fitting on the injector. I've replaced #4 for this reason, but still need to get some clips replaced. Hans says this is very common if the clips are bad.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

If you take off the stop lever you'll find on the shaft an o-ring that's probably seen better days. MB doesn't list such an o-ring and I couldn't match the o-ring at Pep Boys or Autozone but generic o-ring set had a pair that more or less bulked up to the size of the original one. It's been holding for 2-3K miles now.

The stop lever comes off more or less the same way the shift lever comes off the shaft through the neutral start switch. In other words, remove the bolt that holds the stop lever in place where the shaft necks down.

Sixto
95 S420
87 300SDL

Thanks for the tip on the stop lever leak! I'll give it a try and let you know how it goes...

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1989 250TD Wagon 5-speed, 160,000mi ::: Dark gray metallic / black cloth
1984 190D-2.2 5-speed, 287,000mi ::: Silver-blue metallic / black MB-tex ::: SOLD

For future reference, the tightening procedure for the delivery valve seals is in the TDM (Tech Data Manual), not the 602/603 engine manual - don't ask me why.

IIRC (!) - it says to tighten, then loosen & tighten a second time, then loosen again (or not?) and the third time go to a higher spec. I think it was 30Nm the first two times and 35Nm the third time (basically the same as Peter's lb-ft numbers). If you do it wrong, the pump body can warp, resulting in rough idle, leaks, or permanent pump damage. So be careful! If the engine is running OK you probably did it right.

Photos of what happens if you do NOT have the proper clips in place are at this link - scroll to the bottom:
http://www.meimann.com/images/mercedes/OM603_injection/

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Dave
Boise, ID
Check out my website photos, documents, and movies!

GSXR:

Can you elaborate on the procedure... I need to replace these on my 87 300D and I wondered if you could post the exact procedure to tighten down the new seals.

Thanks!
Marcb

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1960 MB 190Db w/ full sunroof
1985 Toyota Pickup
2006 Honda Odyssey EXL R&N
2001 VW Jetta GLS TDI

Here's what the TDM says, word for word:

To obtain a correct seat of delivery valve holder sealing rings, tighten delivery valve holder to 30Nm and release, tighten once again to 30Nm and release again, then finally tighten to 30+5 Nm. Excessive tightening may cause a leak on elements at low and high pressure end by distortion of injection pump housing.

Interprest as you wish...

As Ed Asner said on SNL, "You can't put too much water in a nuclear reactor."

Sixto
95 S420
87 300SDL

Thanks guys... Can you please elaborate more on the procedures involved... i.e. I've seen several posts and I was hoping someone could list some good step-by-step "how-to's".

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1960 MB 190Db w/ full sunroof
1985 Toyota Pickup
2006 Honda Odyssey EXL R&N
2001 VW Jetta GLS TDI

Does anyone have a source for the stop lever o-ring?

IIRC it's the same o-ring used in the stem of the filter.

Sixto
MB-less