ML270CDI Diesel pump is leaking

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Dernburg Wagon
Posts: 9
Joined: Sun 01 May, 2016 7:47 am
Model you own: w163

ML270CDI Diesel pump is leaking

Post by Neo » Fri 28 Apr, 2017 2:38 pm

Hi all,

My Diesel pump is leaking on the right side (Air filter side). When put my head down in the engine bay I can see the drips (1 every 3 seconds) falling behind the pump. I have checked the fuel lines but my guess is it's coming from the lower left cover plate which is part of the pump. I guess I'm lucky it's on the low pressure side but if I remove the pump is it possible for me (or someone) to remove that cover plate and reseal it?

Thanks for your help.


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300 SLR
Posts: 2045
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: ML270CDI Diesel pump is leaking

Post by Bartman4800 » Tue 02 May, 2017 4:25 pm

Not trying to be pedantic but a few words of warning:

Common rail diesels run at a very high fuel pressure (up to 2000 bar/29,000 psi)

If you get fuel injected in your finger or other body protrusion make sure the ambulance is present.
Fluid injection under the skin is fatal if not addressed immediately!
If you can get medical help you might get away with some nasty scars running up your arm where the surgeon had to cut the skin to flush the fuel out.

To be honest, I think this is a job for the BOSCH diesel specialist

1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

Dernburg Wagon
Posts: 9
Joined: Sun 01 May, 2016 7:47 am
Model you own: w163

Re: ML270CDI Diesel pump is leaking

Post by Neo » Tue 02 May, 2017 4:39 pm

Thanks Bart,

I'm going to be removing the pump to fit a seal kit but I was already concerned about the high pressure and was wondering how long it takes to die down. Your point is very valid so I'll double up on the nitrle groves and make sure that only a long spanner is touching that HP rail when I losen that pump nut. Will also wear googles too.

Thanks again for the "heads up" on this ;-)

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Posts: 14
Joined: Sat 14 Oct, 2017 10:04 am
Model you own: I own multiple different models
Location: Yankalilla SA

Re: ML270CDI Diesel pump is leaking

Post by Roger82 » Wed 27 Dec, 2017 10:11 am

I've serviced my own ML270 high pressure pump, they are pretty simple.

But as a safety note to add to the others, These high pressures can cause the diesel to cut through steel so gloves and goggles will not protect you much.

I do wonder what pressure it's running at idle...
2002 ML270 Classic wife's car
1983 500SEC fixer-upper

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