Fuel Leak

[Patrick]

Hi All,

Discovered a leak coming from the fuel pump beside the gas tank. Is there a rebuild kit I can use? And if so, does anyone have the part number. Secondly, anything else I should be aware of for taking the pump off and reinstalling it. It is a '68 250SL.

Patrick

[Naj ✝︎]

Have a look here:

http://www.sl113.org/wiki/pmwiki.php?n=Fuel.FuelPumpRebuild

naj

68 280SL

[George Des]

You need to first determine which pump you have. The rebuild procedures are as Naj pointed out. Just make sure you pinch off the fuel line from the tank to the pump before you remove it, or you will get a very unpleasant "shower"!

George Des

[dseretakis]

Are you sure that the leak is from the pump and not one of the fuel lines?

Dimitri

[Patrick]

Hi All,

Naj & George Des, thanks for the feedback. The info in the technical manual is brilliant. Cheers to Bob Smith.
Dimitri, I took a close look and the gas is seeping from the pump, however, the lines look like the should be replaced. While I'm there, right?

Patrick

[J. Huber]

So, I too have sprung a fuel leak. (did not know if I should start a new thread or continue this one...)

Anyway, the fuel is collecting and dripping at the point where the fuel feed hose (I believe) connects to the hard line. (see attached pic). The connections at the pump (later style) seem fine. Do you suppose the hose has simply given out at the clamp? can I trim the end and reattach? or is a new hose needed? any input appreciated!

[psmith]

Hi James,

My hose went a few years ago and it was a simple replacement.  But do mind the advice about getting a gas shower.  Glasses and gloves are a good idea, and I bought enough extra line that I could take a couple of short lengths and plug them firmly with golf tees and use them for temporary plugs on the hard lines and pump while I got the old one out and the new one in place.

[jameshoward]

James,

Like Peter and, I suppose, you I needed to change all the hoses at the rear of my car. They'd become very hard and the shrouding had rotted away. At the same time I changed the fuel filter in the bottom of the tank, but never managed to change the filter on the pump although I have it still sitting here to do. As Peter says you stand a pretty good chance of getting covered in fuel. Do have a deep tray with saw dust or better, spill sorb, ready to catch what misses your arms and clothes. I worked with a battery light and had an extinguisher with me also. The car battery was disconnected. If you do it indoors you will very quickly build up a vapour hazzard. It's a job worth doing, though, but given the amount of fuel in the lines and the fact that you're likely to get it all up your arms and on your clothes, you might want to do all the lines (the 2 to and from the fuel tank) and the filters at the same time.

The golf tees idea is brilliant (Joe's, I think); I read about it here and also used it.

JH

[thelews]

Why not just clamp off the supply lines in and out of the pump assembly with hose clamps or if unavailable, lightweight vise grips?  When my fuel pump went out I clamped the fuel tank line and line to the injector pump.  Removed the whole assembly and dripped a few drops, nothing major. 

Turned out the problem was a huge build up of filth (carbon?) inside the electric motor after 150K miles.  Took it apart, blew and cleaned it out and reassembled.  Vrrrroooooom!

[J. Huber]

Great info. So are there more than just this one hose that I should do at same time? Would anyone have the MB numbers of all involved?

I have seen two set-ups as far as the main fuel hose toward engine...

working away from pump, some have the main hose with a special fitting at pump, and a hoseclamp at other end. Then a small section of hard pipe, then a small section of soft hose, followed finally by more hard-pipe...the other cars don't have this small piece (250s?). Pete -- which do version do you have?

What if I clamped off the small soft section? and then the hose into pump from tank? Is that what TheLews is getting at?

Good news is -- I already have plenty of golf tees! (that are not getting much action lately... ).

[thelews]

Is that what TheLews is getting at?

If you clamp off the line from the tank to the pump as close to the pump as you can, that will take care of gas running out of the tank, which is the main problem.  For good measure, clamp off the line to the injector pump.  Then the only gas running out will be what's in the pump assembly itself, which will not be much.  An oil drain pan is plenty wide to catch any dripping.

[jameshoward]

I may be being particularly dense, but I don't see how you can clamp to any useful effect a hose that you're going to replace. At some stage you need to remove the hose in order to replace it, which is where the golf tees come in (one in the old hose that you will remove) and one in the new hose, (that you will replace). Moreover, I tried to clamp my old hose to give me some more control over the inevitable flow of fuel and split the hose wide open; it really was very rotten. I am not sure if you could damage a hose that would otherwise be OK save for slapping a pair of mole grips around it and weakening it. A bit of both methods is probably in order.

James, I just used standard fuel line for the replacement rather than faff about trying to get MB stuff. It's generic fuel line shrouded with some form of material. You need two different diameters. Helpfully, I can't remember what they are, but take a look at the SLS website (www.sls-hh.de) and you should see the parts you need with, I think, the sizes. They also show the fuel filters for the tank and pump. The tank filter can be a real sod to undo. Dan recommended using a spark plug spanner in the hole, which was a great idea. Unfortunately, mine was stuck fast so I had to weld a bolt to a metal bar to get leverage, which nailed it. Whatever you do, just ensure you have good ventilation!

Lews - did you notice an appreciable difference in the sound of your fuel pump after you stripped it down? Mine seems to work fine, but I wondered if the whine was any less noticeable after the maintenance? That said, I should probably let sleeping dogs lie, rather than attempt to maintain the thing and do more damage.

James

[thelews]

Well, I didn't read closely to see which hoses are being replaced.  Obviously, clamping a hose you're removing isn't going to do much good unless you want to buy some time.  If it's the tank to pump hose, I think I'd drain the tank as much as possible.

I didn't notice a difference in sound, it's very present.  I didn't notice a difference in sound before she stopped working either, but I was driving at that point.

[J. Huber]

Well, I crawled under and took a closer look. Santa obviously didn't bring that lift I asked for....

Since the leak is on the engine side of the pump, it only leaks when the engine is running. I carefully identified the leak as about 1 inch above the hose clamp. I experimented by sliding the hose further onto the hard-pipe and clamping behind the apparent split or hole. It worked!

Of course, its only a band-aid -- I'll be ordering a new hose very soon to be safe. That's when the real fun will start -- I think clamps may still work -- if I clamp that small section of hose closest to engine and the tank to pump hose. That leaves the pump unfed and just the fuel in between to deal with... Unless I am missing something. I'll be back.

[psmith]

I've always been hesitant to clamp fuel lines because I'm afraid I'll crack the old rubber.  And I don't do the new lines because I'm paranoid!

Another tip VW shops sell metric sized fuel liines with a nice braided cloth cover just like ours at a good price.

[Garry]

Just a tip
Given that fuel leaking points are notoriously hard to pin point, and I took hours to find one recently, my mechanic showed me a good way to find them by the use of Talc powder around the suspect area that then shows exactly where it is leaking from.