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ML270CDI Diesel pump is leaking

13K views 9 replies 4 participants last post by  sbk1972 
#1 ·
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.
Neo

 
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#4 · (Edited)
Thanks Matt .... I've watch a few Youtube videos since. One states that the leak is an indication of imminent pump failure .... Would you agree with that?

Ok I can buy the seal kit but I've never dealt with High Pressure fuel lines before. Do I need to wait a long time before detaching the rail?
How hard is it to remove the pump? .... Is it likely I will break a fuel line connection (connectors and plastic tubes look aged) when I do this job?

A crazy idea I have is to remove the pump cover (cylinder head they call it) while the pump is still in the car. I could remove the turbo and oil breather tubes to get just enough room to work in there. But I know the pump has to be very clean on reassembly so I though I could cover all around the pump with clean plastic sheet..... Whats your thought on all this?

Hmmm .... I guess this is what will happen eventually
 
#5 ·
Yer I would pull it out and do all the seals. Get the correct tool for the fuel lines to disconnect them and warm them up a little if you can. They do get hard. Remove the radiator top mount so you can lean the radiator forward a fraction. You might just prolong a failure by servicing it properly. If you have the electric fan I would pull it out for better access.


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#6 · (Edited)
Ok my Seal kit is on order.

Been thinking about the best way do this job but then stumbled on the best two Vids on YouTube ...


How to remove Diesel High pressure pump ... on an ML270CDI



How to rebuild high pressure diesel pump


Don't be fooled by his introduction clatter .... This guy makes a good job of these these.


Will report back when I've completed my rebuild.


All the best.
Neo
 
#7 ·
Ok I manged to do the pump rebuild yesterday. I followed all the instructions did the three sets of heads seals and the two green cam chamber seals. Then I refitted it and using my inline fuel primer and the stater motor I flushed diesel through the pump before connecting up the HP line.

Engine is running great .... but something around the back of the pump is still dripping at the same drip, drip rate as before.
Before I take it all apart again does anyone have any ideas what else this could be??? :frown

All the best.
Neo
 
#8 ·
Years ago, I fitted a full seal kit to my ML 270 cdi high pressure fuel pump but it still leaked afterwards, I tried all ways to stop the leak but with no success.
I since suspect that the cylinder heads can warp over time and not sit flat, also I have read that some have had success in resealing the pump, where others have not.

I finished up buying a reconditioned pump from a local motor factors, which has served me well.
 
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#10 ·
Neo7, cant add much but I feel you pain / frustration. i had leaking seals on my old Mitsubishi Shogun, had the seals swapped out by a professional for £700. These lasted 50k before they started to leak again. I did a search and found that adding brake fluid to the diesel when filling up made the seals ` sticky` again and stops leaks. I tried it and it worked. in the end I was adding 3/4litres of cheap brake fluid to a full tank of diesel which stopped all leaks. In the end I sold the truck on but might be worth a go.

Simon
 
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