I just finished doing an overhaul of the cooling system on my recently acquired 96 E300D, including a new water pump and thermostat. After starting the car I noticed massive drippage, and I was like oh crap it better not be the new water pump, but in fact it was fuel that was dripping, almost pouring. Clearly it's just a coincidence because I didn't touch anything near the source of the leak. Attached is a picture taken from underneath the engine. You're basically looking at the IP from the bottom, above it is the intake manifold, and the arrow points to the source of the leak. Is that the fuel prefilter? The reason I ask is that it looks quite different from the one in the parts database. If not, does anyone know what it is? I verified that it's indeed the source of the leak, and not something above it.

A couple other questions, where does one buy those clear fuel lines? I don't see them listed in the parts database. And does anyone know what the "fuel line seal" is? There's no picture of it.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

See this great post by Rick Wiley- 99 e300td injector pump leak

About halfway down the first page, he lists all the part numbers you need. I'd probably start by cleaning things up and replacing those hoses and see what you've got then.

Len

From your photo it looks to me like the leak is from the shutoff switch. It can be the switch itself or the seal between the switch and the IP or the o-ring seals at the fuel line fittings. The fuel prefilter is mounted in the main filter assembly up top and not on the IP itself. As the post above indicated, if the lines are old and brittle you should replace them all. The total cost of the parts is something like $60 and each line comes with new o-rings on both fittings.

Be sure you replace the seal at the shutoff housing too as that was the one area my shop neglected to renew and it leaked after they were done replacing the rest of the fuel lines.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I had a similar problem with my 93 300D. It does create a hell of a mess.

I initailly thought is was the fuel warmer or some other component.

The leak came from the clear fuel line that is between the IP and engine. I had to tighten it on 3 different occassions for the leak to stop. Twice after I had replaced the manifold and injector line.

U can use a stubby 17mm or a cheap knock off that r shorter than the name brands. Use ur imagination to get leverage because the space is pretty tight.

Check that first.

Thanks for the advice. It's the fuel shutoff valve then that is leaking. The leak is coming from the rear of the valve and not from one of the plastic lines. It seems like the plastic just gave up, like a dam that breaks and lets water gush out. If it was a rubber o-ring I'd think the leak would be more gradual. Now I have to decide whether to just try to replace this fuel shutoff valve or take off the manifold and do a complete overhaul of all the fuel connections. Is there any danger of getting a runaway engine after replacing this fuel shutoff valve? On the older models that seemed to be a problem.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I'd replace all the hoses. You see, the shop that I bought it from put in the new shutoff valve without a new O-ring. Well, of course it leaked like hell. They put in the new shutoff valve a new O-ring and it was better. However at this time they disturbed all the fuel lines going to and from the valve and all that leaked too. IMO, id replace all the plastic lines and the fuel filter you have there.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Exactly. There's no way to replace the shutoff without disturbing the lines, and they will leak once you mess with them. If you're removing the manifold, be sure to follow my advice in the other thread about the fuel line clips. Remove them before you do anything else, or else you're almost guaranteed to get plastic bits in the engine. And there's no danger of a runaway engine when you replace this part. It is electrically controlled and either works or the engine doesn't get fuel.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Replace all of the clear lines, as soon as you touch them they will leak. Phil or the dealer can get them for you.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Why don't you also make a run for the Glow Plugs. Take them out and coat the threads with anti-sieze to make sure they are good to go.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

I'm wondering how much I can reach by removing the main fuel filter, I'll see tonight. Remember the manifold is a bit different on the naturally-aspirated engines. If that won't do I'll remove the manifold and in that case, yes I might as well coat the glow plug threads. I have a can of heavy Lithium grease, will that work well as an anti-sieze compound?

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

You can easily replace all of the lines except one without removing the intake manifold. You just have to swing the washer bottle up and out of the way and you can get in from the side and replace them from there including the shutoff valve and its lines. As I recall there is a line on the back of the IP which is the only one you will not be able to reach this way. I think it is the one with the bolt through the end of it.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

As I recall the intake manifold is flatter on the turbo models. Here's a picture of mine. I already removed the washer reservoir but I couldn't see anything without a mirror. Maybe if I remove the fuel filter housing as well it might work. I'll definitely try to do this first without removing the manifold.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

The good news is that the shutoff valve is out and I didn't have to remove the intake manifold. I only removed the crossover pipe, washer reservoir and fuel filter housing which gave me plenty of access. It looks like I have access to all the fuel lines this way and I didn't see any fuel line connecting to the back of the IP. Perhaps this is only on the turbo engines. All the fuel lines seem fine, only the o-rings are flat and I'll definitely replace those, but I think I'll keep the lines. Of course I'll be replacing the shutoff valve. Apparently it has o-rings inside and that's what's leaking, but the valve doesn't seem to be serviceable. I would say overall having all these rubber o-rings in the fuel system is a bad design as rubber tends to deteriorate after some time. I prefer the fuel system of the OM616/617 engines where there is no rubber in the fuel system, other than the o-ring on the fuel filter bolt.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I haven't beena ble to find just the lines or the O-rings. If you are going to replace the O-rings only, you might have to risk going with generic O-rings. When they did it under warranty because they sold me what I called a "dangerous used car" they did replace all the lines which came with new O-rings instead of just doing the O-rings.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

I ended up using o-rings from Lowes and Ace Hardware and they worked quite well, though they were very tight and it took a lot of effort to connect the lines. At least they won't leak. But now I have a different problem. I changed the fuel filter and decided to bleed the whole system with the starter. I kept cranking and cranking until I ran out of battery juice, then I used my fiancee's car to "jump" my battery and crank some more. I've done this kind of bleeding before on my 87 300D (though without the jumper cables) and the engine would start after a few minutes of off and on cranking. Well not this time. So I unplugged the line at the top of the prefilter and I was shocked to see no fuel! Could it be that my new shutoff valve is defective? I really hope not.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL