Is anyone familiar with this leaking fuel sender?

[RichardS]

I would be grateful for any advice about the attached photo of my fuel sender.

As you can see, the white plastic centre part is full of diesel and when the tank is filled up into the filler pipe it leaks onto the top of the tank.

The seal under the bolted plate might also be leaking as well, although it's impossible to tell with so much fuel around, but I can't see how that would fill the raised plastic part.

The sender says "VDO - Swiss Made" on it and is 8 cm in diameter. There is also a number but I can't see it clearly.

The tank is 34 cm deep and I assume that this is a tube type of sender rather than a float. Presumably the tube is a bit less than 34 cm long?

Does anyone know whether a leak on the plastic part can be repaired or do I need a complete new unit?

If it needs a new unit does anyone have any experience of where these can be sourced.

Many thanks

Richard

 

[Tranona]

It is a standard VDO sender unit. Good supplier is www.merlinmotorsport.co.uk Don't know if you can buy the floats on their own, but give them a call. If you want to a bit of searching yourself the VDO catalogue is on www.vdo-gauges.com

 

[Andrew G]

+1 to it being a VDO fuel gauge sender. I have one.
It is relatively easy to remove it and check/renew the seal BUT DO NOT REMOVE ALL THE SCREWS - SEE BELOW. You may not need to spend any $, apart from a new seal.
It certainly shouldn’t leak like that (the seal may be faulty or incorrectly installed).
Can you possibly avoid over-filling too? (the gurgle sound on my filler changes as it nears to being full - and it then spits back if I'm too slow to stop). I can also guess, to within a few litres, how much fuel to put in and go very carefully towards the end.
I’d suggest getting the installation instructions off the web so you can check the seal (cork from memory) and be confident of re-installing it.
Underneath the unit, below the top of the tank, there is a metal ring (say 80mm OD x 60mm ID) with a gap between two of the holes (I think I can see an example of the gap just right of the screw under the black lead in your pic - the fact we can see this makes me suspicious that it has not been installed correctly). The screws are tapped into this ring and hence, if you unscrew them all, it will drop to the bottom of your tank. Bu##er.
The seal is between the unit and the top of the tank.
Unscrew one screw and check its length, put it back and screw it in so there is say 10mm threaded into the partial ring below (you could check another to be sure). Unscrew all the screws to this point (and no further) so the partial ring is still suspended below the top of the tank. You then wriggle the unit to dislodge the seal and pull it out of the hole, facilitated by the gap in the ring.
There is a possibility that the screws are tapped into the top of the tank and that there is no partial ring underneath. This is how I did mine as it was a new tank and I could clean the swarf out afterwards. (I also had to use plastic screws and an insulated seal to stop the sender unit earthing to my aluminium hull.). You will easily see if there is a ring as you wriggle the unit.
Check the seal and replace if necessary . . . good luck, Andrew

 

[RichardS]

Many thanks Tranona and Andrew - that is really helpful.

I'm still not sure whether a leaking seal could allow fuel to fill the plastic centre section as it feels like the diesel would have to run "uphill" to do that but as a first stage I will try changing the gasket. I see that Merlin do a VDO fitting kit which looks the same as mine and seems to be at a "non-marine" price!

I've changed "float and arm" type senders on cars and bikes but I've never seen this dip-tube type before!

Thanks

Richard

 

[Andrew G]

Unless you are in a rush I'd have a look at the seal before investing too many £?? Diesel can be pretty pervasive and can almost flow up hill. Has the boat heeled after it was filled - if so it has only had to flow down hill. Andrew

 

[pvb]

I've changed "float and arm" type senders on cars and bikes but I've never seen this dip-tube type before!

I've just replaced the VDO dip tube sender in my Hallberg-Rassy's keel tank. The sender is 800mm long! Out of interest, I took the old sender apart - it has a tiny plastic float with little brush contacts which run on two very fine wires. As the float goes up or down, the resistance given by the wires changes.

 

[Andrew G]

And those fine wires are not just any old wire (as the "professional" installing mine thought - I took over . . .). They have a specific resistance, top to bottom, which is how it works. Cheers, Andrew

 

[Dave_Seager]

It almost looks as though the cable has been used to make an improvised gasket. I would expect to see a "rubber" gasket between the plastic moulding and the metal tank but the cable is in the way. Is there a gasket under there?

 

[RichardS]

I've finally managed to get hold of an exploded diagram of the sender unit from VDO in Germany who were very helpful and very quick. Excellent customer service from both the USA and Germany.

My sender appears to be a 226-801-015-001G and it is a "traditional" arm and float type rather than a dip tube.

Dave is correct in that it has been mis-assembled in some way as that black rubber ring should not be showing like it is.

Andrew is also correct that there are four 15mm M5 bolts and one 30mm M5 bolt securing the flange. I would never have guessed that!

I can also see from the diagram that a fuel leak past the tank sealing ring will, in fact, end up collecting in the plastic centre part so I suspect that the actual sender unit is probably OK and it is a sealing ring problem.

I should now be able to order the two flange sealing rings and the five bolt o-rings here in the UK.

I can't wait to get on with the job. It is great having my boat in the Med but, on rare occasions, I envy you guys who can just pop down to the coast and get on with things!

Many thanks to all who contributed.

Richard

 

[Andrew G]

Well done Richard. I checked it on www. Interesting that there is only one long screw (its to help you wriggle it in place but it would have to be placed in the correct hole?).
I'd be tempted to use 5 x the long screw to make it even easier - now and next time so there is no risk of confusing long with short. Do VDO have a view? Cheers, Andrew

 

[nigelmercier]

I'd be tempted to use 5 x the long screw to make it even easier - now and next time so there is no risk of confusing long with short.

I painted the head of the long one with red paint.

 

[Andrew G]

That would work (especially if in x years you remembered what the red paint was for). Andrew