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Old 07-20-2015, 11:55 AM
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Join Date: Feb 2014
Location: charlotte nc
Posts: 166
injection pump OIL leak

hi all, I have a 92 300d 2.5 and I have noticed the drivers side motor mount has oil all over it. I used my mirror and looked at the plate on the bottom of the pump and it seems to be one of the sources of the oil leak. the other is on the round red plastic piece on the rear (firewall side) of the pump.

is there replacement seals/gaskets available for these or is it just rtv that is used? are any part numbers available for the seals/gaskets?

I should be able to get both replaced while leaving the pump in that car right?

I know it's not fuel, I have zero leaks on the delivery valve holders and all the fuel hoses are new.

'92 300D 2.5
'99 E300TD
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Old 07-21-2015, 11:55 AM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 26,415
There is a Block to IP O-ring at the front and there is a lage usually square O-ring on the Bottom Pan of the IP.

I am not sure what the red thing is but O-rings seal the other items also. You need to be careful not to push any shafts inside of the Fuel Injection Pump. Seveal Members have done that with the Manual Shutoff Shaft.

Another leak area is the sheetmetal Cover on the side if the Fuel Injection Pump.

Can it be done on the Vehicle? That may be possible but the Pan Screws are usually relly tignt and the Pan Screws on My Year and model are for a Blade Screwdriver and a Blade Screwdriver does not center easily on the Screw when in cramped positions and you usually need to push the Screwdriver agains the Screw so the Blad does not jump out of the Screw Head Slot.
However, I do not know what the Screws on the Later Models look like.

If you go to a Mercedes Parts site that has exploded Views they show the Pan O-ring/Gasket as a seperate part. Likely the O-rings also.
They may also have complete Fuel Injection pump and Governor Gasket Kits.

Any, Bosch Fuel Injection Pump Shop can get them and if you can find the Bosch Number for the complete gasket kit they are often on eBay.

If you get the complete gasket Kit you would get new Crush Washers and O-rings for the Fuel Injection Pump Elements/Delivery Valves Seals along with it. But, I don't know if the kits come with Viton O-rings.

For a possible source of the Bosch Gasket Kit part numbers a few People who did the Delivery Valve seal change bought complete gasket kits.
84 300D, 82 Volvo 244Gl Diesel
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Old 07-21-2015, 12:07 PM
WTB: 94/95 E320 Wagon
Join Date: Oct 2007
Location: Charleston SC
Posts: 2,538
I have replaced all OM603 injection pump seals / gaskets / o-rings leaving the pump in the car EXCEPT the o-ring between pump and engine. Not fun, need a mirror and lots of patience, in retrospect it would be faster/easier to remove the pump and then do them all.

On the OM603, the screws on the bottom plate are Torx, T-20 or T-15 I think.

Never ever ever use RTV to seal anything related to engine oil on a Mercedes diesel engine that has the piston-cooling oil jets. It is possible for a small piece of RTV to break off and flow with the oil to the jet and plug it, and then your engine becomes a doorstop. I suspect that the RTV pieces can go through the oil pump and the oil filter bypass (if your oil filter is old and the primary element is plugged up) and then plug up the jet.
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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Old 07-21-2015, 04:22 PM
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Join Date: Feb 2014
Location: charlotte nc
Posts: 166
it doesn't look like it is coming from the ip to block seal. I have already done the delivery valve holders and the crush washers. I also have the torx bits on the bottom of the pump. where can I find the model number of the pump?
'92 300D 2.5
'99 E300TD
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Old 07-21-2015, 04:41 PM
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Join Date: Aug 2011
Location: Carolina
Posts: 1,334
Should be a lil name plate that lives on the outside of the pump kinda under the stop leaver
Current fleet
1992 300D "IceBerg"
1984 300D "Blues Mobile"

1978 300CD "El Toro" Gone on to be born again
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Old 07-21-2015, 11:19 PM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 26,415
In the pic the Green Arrow points to the Fuel Injection Pump ID Plate.

When the Pan is removed there is going to be 1-2 Cups of Oil inside.
Attached Thumbnails
injection pump OIL leak-m-fuel-injection-pump-number-plate.jpg  
84 300D, 82 Volvo 244Gl Diesel
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Old 01-05-2016, 12:47 PM
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Join Date: Jan 2016
Posts: 1
Change bottom seal of injection pump (IP)

The IP of the old diesel cars has many seals and they get hard over time.
When one breaks, engine oil starts leaking and shows up on the motor
mount of the driver side.

The IP bottom plate seal tends to leak and plenty of engine oil ends up on
the motor mount. The seal/o-ring can be changed without removing the IP
However this requires plenty of finger acrobatics and more patience than
milking mice.

- You need a new seal, use the large seal that comes with the oil-filter.
It is somewhat thicker than the original one but will work. You just need
some muscle to stretch it around the bottom IP plate.

- Also you need new screws to replace the ones that come with the IP.
Get 20 flange screws from McMaster M6 with 1.0 pitch x 12mm long, best
grade they have. The large screw head puts pressure on a more
distributed area.

- Get a little wrench set, like the GearWrench 85035 35 Pc MicrtoDriver Set
to hold the Torx-30 bit and 10mm socket.

- A little mirror the see under the IP

Before you start, remove the fuel lifter pump attached to the IP and also
the fuel heater sitting below the IP on the right side. Clean the bottom of
the IP and make sure the screws (Torx-30) have absolutely clean heads.

Take your time when you try to loosen the screws and make sure the T30
bit is totally inside the screw's head. Use the little wrench to hold the T30
bit. After all the screws (4 or 6) are loose remove the bottom plate and
clean it. Remove the old seal, it might be stuck inside the IP so check
there too and clean the inside of the IP.

Stretch the new seal around the bottom plate and push it against the IP
to hold the seal in place. Hold the plate against the IP with one hand and
use the other hand to screw the new screws in, tight enough so the seal
doesn't come out. This requires patience and may be a few tries to get it

Now change the T30 with a 10mm socket on your little wrench and tighten
all new screws evenly.

Also replace more T30 original screws from the front plate of the IP, one at
a time, with the new screws while you are at it.

Drive your car for a day and check for leaks with a mirror under the IP.
No oil on the motor mount is a good sign that you fixed the issue.

Attached IP picture from web-site of person who hosts Mercedes

Attached Thumbnails
injection pump OIL leak-602.962_pump10_bottom.jpg  
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