Author Topic: Fuel Injection Pump Large Nut  (Read 2725 times)

tel76

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Fuel Injection Pump Large Nut
« on: September 14, 2011, 14:26:54 »
I have the large nut removed from the rear of the injection pump (The large nut that incorporates the knurled adjuster).
Can someone inform me it there should be  a copper/alloy: washer fitted between the nut and the cover,( when i removed the nut there was nothing fitted),
If there is a sealant washer what is the Bosch part #.
« Last Edit: September 16, 2011, 09:36:39 by 280SL71 »
Eric

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Re: FIP Large nut.
« Reply #1 on: September 16, 2011, 06:32:41 »
Hello Eric,

Most likely MB does not supply a part number for this and most individual IP parts. You will need to check with a Bosch distributor or a pump rebuilder, or source the seal yourself once the size is known. 
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

tel76

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Re: FIP Large nut.
« Reply #2 on: September 16, 2011, 07:41:10 »
Hello Joe,
The question i want answering,is there some form of seal fitted and if so is it a copper or alloy: washer or is it a rubber 'O' ring?
One of our members thinks that there is no seal fitted.
« Last Edit: September 16, 2011, 09:36:57 by 280SL71 »
Eric

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Re: Fuel Injection Pump Large Nut
« Reply #3 on: September 16, 2011, 21:22:39 »
Eric,

I took off the large nut about a year ago. My problem was the thumbscrew was leaking oil a bit. BTW, there is an o-ring on it that can only be accessed by removing the nut. The o-ring was only about three years old but always had a small drip. I went ahead and replaced it with a fractional sized o-ring that was a few thousands thicker than the metric. Since it is a static seal, it worked perfectly. Best to replace it while the nut is off.

I did not find any seal between the nut and the body and had the same question as you. I believe that there is NO extra seal. If you look at the face of the nut that goes into the pump, there is a very thin protrusion that I believe seals on the aluminum pump body. So you have steel mashed into aluminum. Same sort of arrangement as a seal ring. The narrow protrusion on the nut cannot have any damage in order to work though. If there is a ding in it, the oil will leak past there. I didn't put any external seal on and mine doesn't leak a drop. You could always call Pacific Fuel Injection and briefly ask them to confirm.
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6