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MB 420SEL 1986-Bought in 2010, MERCURY VELLAGER-1995, NISSAN MAXIMA 1996, Buick Lesabre 1995
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Discussion Starter #1
Hello! respected members-

I am a regular member of W126. One of my friend has E300D 1994. He told me that his MB is leaking diesal from the front of the engine. When I open the hood, I noticed the diesal is leaking slowly while engine is running. It look to me that deisal is leaking from some kind of filter on the top. I am not very knowladgable about diesal MB.

I am giving you all the details with photo-

1- What is the part in blue circle that is in front of the engine on driver side?
2- I noticed leaking diesal from the top of the part- red circle.
3- When tried to tighten the black plastic knob clockwise, diesal leak stops but engine cuts off- yellow circle. Please see attached picture.

4- What is this part in Second picture? That is back of the engine near firewall?

What is this problem and how can I fix this problem? Please pardon me for my ignorance about diesal engine. If there is a link for these problem, let me know.
I am sorry for lack of my knowladge about diesal engine.

Sahai
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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These OM606 engines have a series of fuel supply junctions with o-rings that begin to leak after running for a number of miles. The first pic is of the fuel filter, so this should be replaced, along with a number of the o-rings for all the junctions near there. Your second pic shows the top of the oil filter housing.
 

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MB 420SEL 1986-Bought in 2010, MERCURY VELLAGER-1995, NISSAN MAXIMA 1996, Buick Lesabre 1995
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426 Posts
Discussion Starter #3
These OM606 engines have a series of fuel supply junctions with o-rings that begin to leak after running for a number of miles. The first pic is of the fuel filter, so this should be replaced, along with a number of the o-rings for all the junctions near there. Your second pic shows the top of the oil filter housing.
Thank you very much Zeitgeist- really appreciate it.

Sahai
 

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95 E300, 91 300TE, 84 190D
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782 Posts
Further, you've circled the fuel shutoff valve, which secures the main fuel filter to the housing. There are two O rings on the exterior of that valve, which are replaced every time the fuel filter is.

However, there is also one internal O ring in that valve that is not sold by MB. If that stiffens too much, the shutoff valve will continue to leak even if the two exterior O rings are replaced, which means time to buy a new valve. Some people have successfully opened the valve to replace the internal ring, but it is not an official MB part, so it has to be sized at auto parts store.

Please remember this engine has two fuel filters, the main and the prefilter, located on the right side of that housing ( or above the shutoff valve in your photo). The prefilter is a plastic screen, accessed by removing that silver bolt. It also has an O ring that is sold separately, not included with the prefilter:(

As Zeit says, there are 12 or so O rings on each end of each of the six or so plastic fuel lines around the injection pump which will leak someday when those O rings age. Also, there are fabric covered fuel return lines that connect between the six injectors and then to the filter housing. These will dry out and leak.

FYI, diesel is spelled with two e's:)
 

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Registered
MB 420SEL 1986-Bought in 2010, MERCURY VELLAGER-1995, NISSAN MAXIMA 1996, Buick Lesabre 1995
Joined
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426 Posts
Discussion Starter #5
Further, you've circled the fuel shutoff valve, which secures the main fuel filter to the housing. There are two O rings on the exterior of that valve, which are replaced every time the fuel filter is.

However, there is also one internal O ring in that valve that is not sold by MB. If that stiffens too much, the shutoff valve will continue to leak even if the two exterior O rings are replaced, which means time to buy a new valve. Some people have successfully opened the valve to replace the internal ring, but it is not an official MB part, so it has to be sized at auto parts store.

Please remember this engine has two fuel filters, the main and the prefilter, located on the right side of that housing ( or above the shutoff valve in your photo). The prefilter is a plastic screen, accessed by removing that silver bolt. It also has an O ring that is sold separately, not included with the prefilter:(


As Zeit says, there are 12 or so O rings on each end of each of the six or so plastic fuel lines around the injection pump which will leak someday when those O rings age. Also, there are fabric covered fuel return lines that connect between the six injectors and then to the filter housing. These will dry out and leak.

FYI, diesel is spelled with two e's:)
Thank you DS- Sorry for the spelling mistake.

So far I only notice leak from the shut off valve. Is it possible to replace the shut off valve ( blue circle in the picture)? will that solve the issue at this time. I might get the shut off valve from the junk yard.
 
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