Recently, my 240D has been leaving a small puddle on the ground when parked for more that a few hours, especially in the summer heat. After further investigation, I have realized that fuel appears to be leaking from some patches around the fitting on the forward end of the tank where the strainer is and the fuel line attaches. I had a shop look at it up on the lift, and the mechanic seems to think that much tampering with it will mean the end of this fuel tank. Has anyone else seen this before?

At this point I'm thinking of pulling the tank and making it my Veggie oil tank for my 2 tank conversion which I've been working on. I will use a small 5 gallon tank in the trunk for my start/stop fuel. I have a metal worker friend who has worked on fuel tanks for SVO conversions, and he can probably do the tank work. It seems like the only long term solution is to replace the tank or weld a new piece into the tank and re machine it for a fuel pickup. For my situation it seems like the second option would be the better of the two in terms of cost. What do others think?

Unless you look yourself, after cleaning the area, I don't think you can be sure of what that mechanic told you... the hose clamps were not tight on mine when I checked it... and the hose was OLD.... probably the original....
I took mine tank out and power washed it...
I renewed the rubber hose there....and there would be a potential for leaking just from the threads for the tank strainer...
Why don't you wash it at a car wash... and then keep looking until you see the start of the leak ?

The rubber hose definitely needs to be replaced, but the mechanic believes that in replacing it, the fitting at the tank for the strainer and hose barb will separate from the tank. It looks to me, and to the mechanic, like the tank has been patched around the fitting, and this patch seems to be weakening.

I will take your advice and try to wash the area as well as possible and perhaps this will shine more light on the situation, but I'm expecting some repairs need to be done to the tank itself. Perhaps I will be pleasantly surprised.

This is so wierd, my 240D tank also sprung a leak and is making an unholy mess. I have been so busy, that I havent had a chance to pull the back metal off from the trunk to see whats going on, so its parked for a little while. It happened all of a sudden after my first B100 tank of the year and it seeps into the trunk and luckily follows the "ditches" to the frame-drain. it doesnt happen if its sitting there, only during driving. I checked all the lines and connections bellow the car and it is definetly not coming from there. I was wondering if the biodiesel rotted through something and then when the car is being driven, it sloshes out of a compromised seal between the fill and the tank. But, like i said, that should be answered when i pull the sheild off. anybody have anything similar happen?

I had a leak on coincidentally, the 240D a month or two back, but mine was a deteriorated return line where it attached to the tank. Cheap fix but a pain in the ass to do, the hole clamp was above the subframe facing the wrong direction, I ended up cutting it off.

If you could provide a picture (after hitting it with some brake clean or similar product) we could help diagnose it better.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

seems unlikely. those tanks are pretty rugged. the hoses that come out of it do fail often after 20 years or so. i am betting that if you replace the line section that comes out of the tank all will be ok. i recommend using factory parts.

also, if it breaks it breaks. what choice do you have? i wouldnt pull the tank until i try to replace the leaking line.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Well, this is the thing. I have several choices. Due to the fact that I am doing an SVO conversion on this car, I am now thinking about pulling the tank and adding a coolant heated fuel pickup to it for SVO use. This would give me much better Veg. capacity than a five gallon tank in the trunk, which was my first option. It would also allow me to really inspect the tank and figure out if it has been compromised, and repair it if necessary.

So, I can replace the hose, which is easy except for the mess factor. Then continue my Plan a which is a 5 gallon tank for SVO in the trunk. I can pull the tank and inspect and possibly repair it, and then modify it for SVO use. I can potentially leave the tank in place and not use a heated pickup, but still use the tank for SVO by just plumbing to the existing fitting. Too many options.

I'll get under there this evening again and try to get a photo with the area cleaned.

the plot thickens... a pun related to the veggie oil.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Got under the car this weekend and got this photo. I tried to remove the old hose and replace with new factory part, but hexagonal fitting in the tank began to move as I attempted to rotate the hose fitting out. The blue goo on the tank is flexible and I can push my finger into it and flex it with no fuel in the tank.

My guess is that someone damaged the tank at some point and repaired it with the goo. Now the goo is leaking.

Attached Thumbnails

 

"got this photo." It did not post... try again...

It should be there now.

looks a little like silicone. if so then it is time to do a proper repair or replace the tank with a good used one. since they rarely go bad they should not cost too much.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.