It just occurred to me that Type III fuel senders are almost unobtainable, and Type IV ones are pretty much totally unobtainable, and if you find some they cost alot.
Having just rebuilt my Type IV sender, and having had this problem before, it just occurred to me that maybe alot of people consider them non-repairable, and when the sensor dies they just either live without a fuel sender, or try to find a new/second hand one. I may be wrong, but iv never heard of anybody rebuilding one before.
I rent a corner of a classic car workshop specializing in VWs (i dont work for them, i just rent abit of their space) and when i was rebuilding mine they were all crowding around me looking at me like im an idiot, and then watching in amazement that im actually taking apart and fixing a fuel level sensor. One of the people there suggested that to most people, even mechanically minded people, its not really obvious that these things can be fixed, so i should perhaps tell people.
The reason these sensors die is because they are a stupid design and have very fragile components. They are very vulnerable to the guide rod rusting.
It especially effects cars which have been standing a while. They are also hard to take apart without breaking everything even more.
So, if anybody has a dead fuel sensor, don't throw it away just yet, it may be fixable. About 50/50 or maybe even 60/40 that its possible to rebuild it. Iv rebuilt a few now, all of them looked awful but only one was too far gone to fix.
Anybody has any dead sensors that they would be interested in getting fixed?
Got any dead fuel level senders? They may be fixable!
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purplepeter
- Posts: 2339
- Joined: 8th August 2006 - 4:41pm
- Location: Bath, Avon
Re: Got any dead fuel level senders? They may be fixable!
Its covered fairly extensively in the Club Technical Manual,& to a lesser extent on the club technical pages online www.hallvw.clara.net/fuelsend.htm ..Do a search
Re: Got any dead fuel level senders? They may be fixable!
I think quite a few have had to investigate them over the years, but mainly to clean deposits off. They don't really wear out like the sweep contact wire-wound type, which I've had to replace on other VWs at a much younger age.
We've had something up about this on the website for at least 10 years! Jim Adney in the USA has managed to get a supply of the wire - my investigations suggest it is around 44 swg nichrome to get the sort of resistance needed (220 ohms / metre is in the right ball-park). I think I worked out it needs about 100 ohms total resistance, but that would need checking. http://wires.co.uk/acatalog/nc_bare.html does a range of such wires and even better sells 10m of it at a realistic £5 - £6. Subject to checking, it would be worth getting some for the club to sell on. It would be easy to put a variable resistor between the earth and wire to the gauge and find the least resistance that gave empty on the gauge.
It's not the easiest material to solder - I think it needs a special flux. You may be able to add something there. One of the other forum guys has had to remake an earth connection from that end of the wire to the cap as corrosion had made it open circuit, or high resistance anyway. His photos are on the page too. http://home.clara.net/hallvw/fuelsend.htm
I never throw away anything - as some of you know! Even the odd screw salvaged from a broken part may be an unusual size.
I have to defend the design. How many of the wire-wound type give problems by 10 or 15 years old? I've changed them (not fixed - it's much harder to fix them) on a Camper and a Polo. I've only had to clean up the thin wire on the Fastback - the others still work after many more years. The best of all is the old Beetle one which has a Bowden cable and a red tab that moves up and down in a frame on the dash when the float moves up and down. It reads when stationary with ignition off too!
Do you have access to this thickness, or does it make sense to buy some in?
We've had something up about this on the website for at least 10 years! Jim Adney in the USA has managed to get a supply of the wire - my investigations suggest it is around 44 swg nichrome to get the sort of resistance needed (220 ohms / metre is in the right ball-park). I think I worked out it needs about 100 ohms total resistance, but that would need checking. http://wires.co.uk/acatalog/nc_bare.html does a range of such wires and even better sells 10m of it at a realistic £5 - £6. Subject to checking, it would be worth getting some for the club to sell on. It would be easy to put a variable resistor between the earth and wire to the gauge and find the least resistance that gave empty on the gauge.
It's not the easiest material to solder - I think it needs a special flux. You may be able to add something there. One of the other forum guys has had to remake an earth connection from that end of the wire to the cap as corrosion had made it open circuit, or high resistance anyway. His photos are on the page too. http://home.clara.net/hallvw/fuelsend.htm
I never throw away anything - as some of you know! Even the odd screw salvaged from a broken part may be an unusual size.
I have to defend the design. How many of the wire-wound type give problems by 10 or 15 years old? I've changed them (not fixed - it's much harder to fix them) on a Camper and a Polo. I've only had to clean up the thin wire on the Fastback - the others still work after many more years. The best of all is the old Beetle one which has a Bowden cable and a red tab that moves up and down in a frame on the dash when the float moves up and down. It reads when stationary with ignition off too!
Do you have access to this thickness, or does it make sense to buy some in?
Dave.
Re: Got any dead fuel level senders? They may be fixable!
Well, i was actually investigating the wire myself. I think the general consensus at the moment is that its NOT nichrome! Nichrome does not like soldering at all, but this stuff solders reasonably nicely. Got a couple of wire suppliers who might be able to get a match assuming I can get a sample from a broken sensor.
I got an approx reading of 1.4r/cm, so thats 140r/meter, and 0.05mm thickness or so. But that's with a cheap crappy multimeter, so its probably wrong.
The other thing I thought of is replacing the center guide rod with a stainless steel TIG welding rod! That would solve the rust problems on the center rod once and for all.
The rod can be held in a vice using a CuNiFe brake pipe cut in half length ways to make kind of like pipe-shaped soft-jaws, to stop it deforming the rod. Tap one end for the thread to hold the retaining nuts, and press the ally cover onto the other end. Then you can use a small hammer-struck jig to squish the rod near the top to form the back-stop for the little plastic wire holder, just like the original.
Then at least the float will never rust solid to it again.
I got an approx reading of 1.4r/cm, so thats 140r/meter, and 0.05mm thickness or so. But that's with a cheap crappy multimeter, so its probably wrong.
The other thing I thought of is replacing the center guide rod with a stainless steel TIG welding rod! That would solve the rust problems on the center rod once and for all.
The rod can be held in a vice using a CuNiFe brake pipe cut in half length ways to make kind of like pipe-shaped soft-jaws, to stop it deforming the rod. Tap one end for the thread to hold the retaining nuts, and press the ally cover onto the other end. Then you can use a small hammer-struck jig to squish the rod near the top to form the back-stop for the little plastic wire holder, just like the original.
Then at least the float will never rust solid to it again.
Death to FF!
Re: Got any dead fuel level senders? They may be fixable!
I've only taken two apart - neither had the float rusted in place, but they weren't sliding smoothly or working smoothly due to dirty wires. It's easy enough to measure the whole length with the sender out and the float on the bottom; the one I 'serviced' while the method was fresh in my mind measures 98 ohms for the total wire length, which I took to be about 30cm altogether. I had some broken wire from another which I measured with a micrometer, and I'm pretty happy it agreed reasonably with the nichrome table for resistance per meter. I don't recall how much it was, and can't remember where the wire is now to check.
I suppose you may have been soldering already tinned wire? Suggestion is that acid based flux is the stuff to use (there's an e-cigarette website which mentions that - I had no idea or need to know there is such a thing!). They make small heating coils that run on a battery to vapourise nicotine for their 'fix'.
The fun of repairing it yourself is partly having to get round particular difficulties. If the fight is too easy, it's not satisfying, but there are limits to what is still fun. Lying on my back with a blob of weld spatter finding it's way past my welding helmet into my ear comes quite low on my enjoyment spectrum!
I suppose you may have been soldering already tinned wire? Suggestion is that acid based flux is the stuff to use (there's an e-cigarette website which mentions that - I had no idea or need to know there is such a thing!). They make small heating coils that run on a battery to vapourise nicotine for their 'fix'.
The fun of repairing it yourself is partly having to get round particular difficulties. If the fight is too easy, it's not satisfying, but there are limits to what is still fun. Lying on my back with a blob of weld spatter finding it's way past my welding helmet into my ear comes quite low on my enjoyment spectrum!
Dave.