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  #1  
Old 11-06-2009, 07:52 PM
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Unhappy ?Fuel in oil?

My neighbor has a beautiful 1985 300cd European delivery with i believe less than 50,000miles.The oil level in the crankcase has gone up leading him and i to think the fuel must in some way be getting thru a seal of some sort in the injection pump.Do any of you people with experience with the 617.952 engine have any other ideas of what might cause the oil level to rise? Is this a seal that can be replaced without complete dissasembly of the injection pump or is this strictly a job for a Bosch shop? TIA Don

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Old 11-06-2009, 08:53 PM
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Well, the two can get together in the IP, but do a smell test of the oil.
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Old 11-07-2009, 01:15 AM
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There is a tiny O-ring in the Fuel Supply Pump that is on the side of the Fuel Injection Pump that seals the Rod that pushes the piston in it.
I have seen that leak in the past and cause Diesel to get into the Engine Oil on other types of Bosch Fuel Supply pumps.

However, there is another thread where it is claimed it is the Oil that gets suck into the Diesel Fuel.

The size given for the O- ring was 5mmx1.5mm (the 1.5mm is the cross section of the O-ring/thickness).

The only other place the Diesel Fuel can leak into the Engine Oil is if it is leaking around the Elements inside of the Fuel Injection Pump.
The reason the Elements leak is most often is that the are scored/scratched a Fuel leaks buy them.
The other reason is rare; the Steel Element erodes or rust in the area it seats in the Fuel Injection Pump Housing.

Removing the Elements will change the Factory Fuel settings for each Element.

Unless your friend has an M type Fuel Injection Pump there is cover that can be removed to observe the Elements.

Below is a pic of (this is not an M Pump Element) of the more common Fuel Injection Pump Element. There is an O-ring that goes at the top but I believe it seals metal to metal in the Fuel Injection Pump Aluminum Housing. But, I have never had one of these Fuel Injection Pumps Apart before.
Attached Thumbnails
?Fuel in oil?-w-bosch-element.jpg  
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Last edited by Diesel911; 11-07-2009 at 01:32 AM.
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Old 11-07-2009, 01:54 AM
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Most likely

culprit is the Mechanical Lift Pump o-ring(s) seals
(Lift pump is on the side of the I.P)

Rubber o-ring(s) rupture and allows Diesel into the Crankcase.
[Pictograms and parts from a W124 Diesel ,yours may vary]
[And if it's a OM617 Diesel,the lift pump may not have a repair kit inside of
MB's Parts System...But,Bosch will!]

Parts # 557 and 560 in Cyrillic Pictogram below:
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?Fuel in oil?-screenhunter_01-nov.-07-18.11.gif  
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Last edited by compress ignite; 11-07-2009 at 06:20 PM.
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Old 11-07-2009, 05:22 PM
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I have never seen any Bosch Fuel Injecion Pump with a Fuel Supply/Lift Pump that has a Diaphragm.
However, some Diesel Engines do use them and on those Engines they do rupture and leak Fuel into the Engine.
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Old 11-07-2009, 06:16 PM
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Thanks

Diesel911,

For straightening out my memory...No Rubber Diaphragms (O-rings only)
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Old 11-08-2009, 08:03 PM
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Thanks guys ,when he gets that pump off we will have a look around for the O rings.I looked for a part number for them but nobody seems to break the lift pump down just sell it as an assembly.I guess we will have to find a Bosch shop. Thanks Don
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Old 11-08-2009, 10:51 PM
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Quote:
Originally Posted by oldiesel View Post
Thanks guys ,when he gets that pump off we will have a look around for the O rings.I looked for a part number for them but nobody seems to break the lift pump down just sell it as an assembly.I guess we will have to find a Bosch shop. Thanks Don
There is only 1 O-ring as pictured below with the Red Arrow.

The Yellow Arrow in the 2nd pic points to the groove the O-ring goes in inside of the Fuel Supply Pump.
Attached Thumbnails
?Fuel in oil?-w-o-ring-supply-pump.jpg   ?Fuel in oil?-w-o-ring-supply-pump-groove.jpg  

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