I did a bit of searching around, but couldn't find a similar topic. I discovered a fuel leak the other day on my Dad's 99 E 300 Diesel that was associated with a hose running from the center of the fuel filter assembly down to the injector pump. The original had a 90 degree fitting and hose that led straight into top of pump assembly.

Figuring the hose had a crack I didn't see, I replaced the whole thing with a new part from MB. The part was slightly modified from original, but seemed to fit the same way.

Unfortunately my quick fix didn't work and there is still leakage around this hose. Can this be a sign of something other than a leaky hose?...perhaps a clogged or clogging filter that is creating excess back pressure? I am not really sure what this hose does...if it is a return line or something else.

I know VW diesels well, but this is a very different set up, so forgive me for asking what may be very basic questions.

Thanks in advance for any advice or direction.

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Tony B.
1999 E300D

Not uncommon in that engine. Many of us just replace every hose and O ring as a preventative measure. Total cost around $100 or so. The hoses themselves not only leak, but so does the fuel shut off valve that is bolted to the injection pump. Do a search and you'll find lots of info about the problem.

Len
'99 E300TD

Once again, sorry for the elementary questions...and thanks for your reply!

Upon further investigation, it appears the fule is leaking from a seam where a black piece attaches to the side of the injector pump. Is this the fuel shut off valve? This piece has two fuel hose inlets/outlets on top, and one on the side.

If this is the shut off valve, how expensive a part is this?

I can work over a VW diesel in my sleep, but this is my Dad's car, and has a lot of parts I am not familiar with.

Thanks in advance for any advice.

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Tony B.
1999 E300D

YES, it's the shutoff valve.

It's probably just the o-ring between the fuel shutoff valve and the injection pump. It is $1.40 from Phil at Fastlane.

The shutoff valve is $142 from Phil but I doubt it's bad.

I would suggest replacing every single line you disturb as they are prone to leakage when they are "tweaked" after the o-rings take a set. Probably would be a good idea to replace ALL the lines (minus the one you just replaced).

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2005 Pathfinder LE
2001 E55
1998 M3
1982 320i

That's it - replaced mine a year or so ago. I think the cost was about $130. It's also a possibility that you may only need to replace the O rings.washers. I replaced mine because it was throwing a fault code.

Len

Hi Len, was yours the one setting the Fuel Temperature Sensor fault code?

I presume replacement of the valve fixed it?

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2005 Pathfinder LE
2001 E55
1998 M3
1982 320i

Thanks a lot for the info! Does replacing the valve or O-ring necessitate removal of the intake? I can't even see any attachment bolts or screws down there. I'd like to help my Dad, but don't want to make this a weekend project!

Thanks again for your assistance. This group is outstanding...I was looking around and am amazed at the wealth of info. Makes me want to trade my VW diesels for a REAL diesel!

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Tony B.
1999 E300D

1. Yes, the fault code was P0180, fuel temperature sensor, and yes, a new fuel shut off valve fixed it even though the WIS diagnosis procedure didn't seem to indicate that was the fix. it's been over six months now and no check engine lights - sure is nice.

2. You may be able to replace the unit with the manifold in place, but I would remove it. It is so much easier that way and since I've had my manifold off/on so many times, I can do it in about fifteen minutes now. If it was my car, I'd change all the fuel hoses and the glow plugs while I had the manifold off, but maybe that's just me. There are two bolts, maybe allen, holding it on.

Len

Hi there are 2no. Torx head bolts that hold the shut off valve onto the pump mine happened about 2 months ago. I was able to replace it without taking off the manifold but i have a 2 post ramp. If u remove the washer bottle u might have a better chance.

McCool300TD

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1988 190E Sold
1996 C230K Sport Sold
His: 98 E300TD Estate, 7 seater, Avantgarde, Silver, Black cloth, parameter steering, dipping rvm, folding mirrors, rain sensing wipers, pentagon tints, 17" Elegance wheels. 298K
Hers: 93 300TD, 7 seater, Grey MB Tex pearl blue metallic, 15" 8 hole alloys, OTG, Cruise, not much else 220K

Yes you have to remove the intake manifold to properly install those new plastic lines... You might as well replace all of the lines together rather than one by one, because there is a high probabilty that if one of the other lines are leaking, you won't know it until the motor doesnt fire and you are stuck at an inconvenient place.

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2005 SL65
1999 E300
1995 E300
1994 SL320
1988 560SL
1987 300TD
1982 300D
1955 300SL

Thanks for all the info. I got an o-ring, and while wishing for a couple of more elbows and wrists on each arm, I managed to replace the shut off valve o-ring. I plan to buy up all the hoses and do the full job ASAP. I was just glad to get the car in working condition again with this quick fix. This is a great resource, and I can't thank you all enough!

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Tony B.
1999 E300D

You can actually replace all the plastic fuel lines except for one without removing the intake manifold. I did it recently on my '98 E300 by removing the fuel filter manifold which opens up enough space for your arm to reach down under the shutoff valve to get at that really short one. The only one I was not able to replace was the return line to the tank, which has a real through-bolt banjo fitting on it (and its not under a vacuum) to I was not too worried about skipping that one.

Make sure to get a new prefilter O-ring since these are not included with the prefilter!

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Scott C.

2006 E320 CDI (120k miles)
FOR SALE: 1998 E300 Turbo Diesel - Black w/Tan Leather - Euro delivery (236k miles)