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Westy water tank level sensor repair

Printed From: The Brick-yard
Category: T3 Section
Forum Name: Useful Westfalia threads
Forum Description: A forum to squirrel away some of the more useful threads relating to Westfalia models
URL: http://www.brick-yard.co.uk/forum/forum_posts.asp?TID=42742
Printed Date: 20 Sep 17 at 06:43
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Topic: Westy water tank level sensor repair
Posted By: Holydiver
Subject: Westy water tank level sensor repair
Date Posted: 19 Aug 09 at 13:59

< ="-" ="text/; =utf-8">< name="ProgId" ="Word.">< name="Generator" ="Microsoft Word 9">< name="Originator" ="Microsoft Word 9">
Westy water tank level sensor
Before I explain how I fixed my level sensor for the second time I would recommend that you also read a thread posted here or on 80-90 forum by Lagerhead on 13th Mar 07 titled water tank depth gauge – fixed that too! or I have it on a word doc that I could e-mail if required, as I found this very useful first time around plus it explains how the sensor works.
 
The first time that I fixed my level sensor it was just a case of reading the above thread following the instructions and replacing the lower reed switch, that was that until last week when I noticed that it was not working again.
This time it was not possible to strip and take apart the sensor tube as before because I did to good a job of gluing it all back together, this time I had to gentle cut around the tube in-order to get to the switches inside. On closer inspection I found that the tube had cracks in it which had allowed water in, thus creating a short circuit and giving a fails reading on the display.
 
Knowing that the sensor was working fine (once dry) my next problem was what do I do next being that I had cut the tube up in-order to get to the sensor inside, lucky for me a quick and successful call to one of our plastics suppliers at work and the next day they delivered 2mts of 10mm acrylic tube.
 
The following explains how I rebuilt the sensor (If you are stuck I do have tube, resistors and reed switches to build another 2 or 3 for £12.50 +P&P)
 
1. First I drilled out the centre of the base mount to 10mm.

 
2. I cut a length of tube to 375mm and than super glued it into the base so that it was flush with the top.
IMG]http://i191.photobucket.com/albums/z176/sbbfuk/P8100169.jpg[/IMG]
 
3. Next I threaded the sensor into the tube so it was almost flush with the end, a small blob of silicone at both ends to fix it in place.

 
4. Now it was just a case of fixing the stops in place, this was done by simply connecting a multi-meter across the two wires and measuring the resistance whilst sliding the magnet up and down the tube. Once I was happy that it was all working I super glued the stops in place.
Top stop


In between

 
Bottom stop


5. To finish it off I found a tight fitting cap for the end (Mine was the red cap that comes on a roll of 10mm Hep2o) and then used a bit of heat shrink over that just to make sure it was water tight.
I also took the opportunity to make the wires longer and used bullet crimps so that I could easily disconnect the wires when removing tank lid. 

The finished item


Reed switches and resistors used all from RS


Hope this is of help to someone.Smile





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Replies:
Posted By: Joker_Club
Date Posted: 19 Aug 09 at 16:48
Top fella, good info and pics there, ultra-useful Thumbs Up

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Sunny Lancs


Posted By: jameshere
Date Posted: 20 Sep 09 at 02:58
   Just managed to find your post again in Usefull Threads!  No luck finding the one by "Lagerhead" that you referred to - could you please send it to me if you still have it - sound as if it describes the operation of the gauges in depth (no pun intended!)
   I am wondering what model the gauge illustrated was from? It looks a lot longer than my Florida unit - not that that is relevant, as long as they  work on the same principal.
James    


Posted By: Holydiver
Date Posted: 21 Sep 09 at 13:42
Hi James

I have it as a word doc, so could e-mail it to you if you want??

Just PM me your e-mail and I'll send it.

Cheers
G


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Posted By: Joker_Club
Date Posted: 21 Sep 09 at 14:39
Is it worth posting back to here Sbffuk?

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Sunny Lancs


Posted By: Holydiver
Date Posted: 21 Sep 09 at 17:20
Hi
Here's the write up done by Lagerhead, sorry no photo's but I do have them in the word doc so can e-mail that it anyone needs them.


Posts: 913 Topic: water tank depth guage - fixed that too!
Posted: 13 Mar 07 at 00:12
One of the apparently common failings of the westfalia kit is the depth guage inside
the onboard water tank. I made it a mission to replace mine until I found that they
could be repaired. Here's what I did
A post from Lagerhead on 80-90 was really helpful as it led me to understand how
these work and consequently how the inners must be constructed to enable it to be
manufactured consistently.
As he says, they work by the float (which contains a magnet) opening and closing 2
reed switches to effect a pre-determined amount of resistance (through the two inline
resistors). The amount of resistance makes 1 of the 3 LED's in the control panel light
up. Simply really!
It appears to me that these sender units quite commonly fail for 2 main reasons:
a. the plastic rod leaks and takes on water which causes corrosion and deformation of
the copper strip.
b. the magnetic reed switches break (probably because the rods get bent or they are
made to bend due to water getting in and so causing the double sided copper clad
"rod" to bend)
NOTE- these rods are actually VERY fragile, so NEVER try to straighten a bent
one - this is what breaks the glass reed switches!
So, to repair them (mine was pretty well trashed, so i reckon that they can always be
fixed as long as all the main component parts are still present):
1. unplug the 2 wires to the depth rod (black and green) from the clear multi-plug
connector block which is found in the rearmost locker under the westy table
(you will need to remove one small screw to swing a metal plate back to
reveal the lid to the water tank).
2. Remove tank cap/lid and carefully withdraw complete with rod.
3. You may have to carefully "break" the glued connection of the rod and the
grey mounting cap, mine slipped out easily but they were originally glued.
4. Snip the connections of the two wires where they enter the top of the plastic
rod to free it.
5. using a sharp knife, break the seal of the glued grey plastic cap at the bottom
of the rod and remove the plug (this is where they seem to leak from)
6. push the inner rod through from the top (where the wires were) or use thinnosed
pliers to pull it from the bottom - it should only be glued / sealed
slightly at the top if at all.
7. Once you have all the pieces, it should be obvious that the tiny magnetic reed
switches are broken, mine were filled with water and like tiny spirit levels
with bubbles in too!
(all the bits..)
(
upper switch..)
(lower switch..)
8. Obtain new reed switches and desolder the old ones to replace with the new,
ensuring the rod itself is kept absolutely flat and straight - DONT TRY TO
BEND IT AFTER SOLDERING! or you will break the reed switches again!
(The switches can be found at Maplin, RS and Farnell, but look carefully at
the description, these are miniature switches and there's no room for anything
bigger! The top one is a SPST type - single pole, normally open (ie open
circuit until a magnet goes over it), the lower one I found much more tricky to
locate a supplier for as it's a DPST - double pole - this one has to be soldered
in to be closed and the "open" leg cut off short and not touching or soldered to
anything.) You can easily test the switches with a multimeter and a magnet to
check connections etc.
9. Ensure there are no short circuits, solder lumps or bumps, or anything more
than about 2-3mm above the surface of the rod, as if there is, it may not work,
or may not go back into the sleeve.
10. Depending on how easily your rod will feed back into the plastic sleeve, you
may need to go from the top or bottom - if you cleaned all the glue out, it
should make no difference. However, if you have to push it up from the
bottom, then carefully push the copper rod complete back up into the plastic
tube, pushing it through about 1/2" clear so you can resolder the wires to both
sides at the top.
OR.. solder the wires on first (doesnt matter which goes to which side, but
make sure no solder short circuits the two sides!) and push the rod back into
the tube from the top.
11. push the copper rod back in flush, seal with silicon or similar to prevent
moisture getting in, replace the bottom plug and glue it / seal it.
12. I used bathroom sealant to seal the lower plug and also the seal between the
rod and the grey plastic top that is screwed to the tank cap- whatever you use,
remember that's your drinking water in there!
Hey presto - you should have working LEDs again; stand back an admire -
oooooooooh, fairy lights! (the top switch on the display should show you battery and
water levels)
If you need the reed switches and cant get any, I have some (only a few of the double
pole ones tho) and can supply one for each of the top and bottom for 10 inc postage.
I might even consider repairing these for others, it takes about an hour once you've
got all the bits, or 3 weeks if you learned on the way and had to track down the parts
like i did!
Hope this helps!


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Posted By: Joker_Club
Date Posted: 21 Sep 09 at 18:05

Cheers mate, I will go through the whole thread now and edit it so all the info is in sequence etc. Top fella Thumbs Up Thanks to Lagerhead as well, wherever he may be Smile



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Sunny Lancs


Posted By: Lagerhead
Date Posted: 22 Sep 09 at 22:48
I'm here!!!
 
Unfortunately I can't claim that write up. I think I posted how the switches worked on 80-90 whilst I was mending mine and another member on here added the detail to it.  Funnily enough, once I mended mine I stopped using the tank as I couldn't be bothered to clean it after it had been left for a while.  We use bottles filled from the tap now...


Posted By: Holydiver
Date Posted: 23 Sep 09 at 13:01

CLEAN!!!!

Whats that?? mind you don't use are for drinking water.


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Posted By: Zeb
Date Posted: 08 Jan 10 at 20:37
Top post sbbfuc.

I thought my sensor was faulty following stripping and refitting the van, it now always reads full regardless of water level. Surprisingly I took the sensor out and checked it with a multi meter and it's fine?

Looking through the Bentley manual it gave the steps to check the panel but unfortunately for an older model. I struggled to follow the instructions and eventually gave up.

Can you offer any advice to check the display panel or maybe an alternative reason for the fault?

It particularly pisses me off cos it was fine until I stripped and rebuilt the van.

Any help is appreciated

Cheers

Zeb


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 11 Jan 10 at 10:02
Hi sorry not sure I can help as my fault was with the sensor, so never needed to look further than that.
Sorry
 
Are you sure it's not the sensor?? because they are fragile, I had to strip mine twice.
Top reed sw't 1st time and bottom second.


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Posted By: Zeb
Date Posted: 11 Jan 10 at 21:43
Hi Yes I'm pretty sure it isn't the sensor but I'll check again. I had three readings from it when sliding the magnet and as usual I probably did it half a dozen times to be sure, is there a range for each reading I should be looking for?

The reading from empty to full is very different but I did not record them, it leads me to think there is either a wiring problem or that part of the panel is buggered. If there was an easy way to check the panel it would be very useful as it is so simple to remove it.

I'll record the readings when I get the chance to check it again and compare to what you show in your post.

Cheers

Zeb


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 12 Jan 10 at 08:36
Hi
Yes- a quick way to check would be and I think I did is.
1. with a bit of wire short out between the supply and return wire and see which LED lights up (green / Red)
2. do the same again but with one resistor in line and Amber LED should come on
3. same again but wth 2x resistors in line
 
Down side is you will need a couple of resistors 


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Posted By: Zeb
Date Posted: 12 Jan 10 at 20:41
Time to go and search, I must have some electrical widget with resistors somewhere I don't need !

Thanks


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 13 Jan 10 at 08:11
Hi
I've got some PM me your add and I'll send them to you.


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Posted By: Zeb
Date Posted: 18 Jan 10 at 23:21
Hi sbbfuk

The resistors arrived today, thanks very much you have saved me a load of hassle looking for a fault elsewhere in the system. I tried them out and got the correct panel readings instantly.

The level of resistance I was getting when I originally checked the sensor was too low to be correct. This gave me the confidence to dismantle the sensor and have a better look. After scratching my head for a while I discovered the top reed switch connection was burnt (under X10 magnification) it is not disconnecting properly and gives the false reading of full regardless of what the lower reed switch is doing. I can actually hear the lower switch click as the magnet passes over it so it seems to be fine and the contacts also look clean.

So I think all that needs to be done is replacement of the top reed switch.

Looking at the picture in your post I checked RS for the part numbers, I am now confused as both "394-428" and "229-3692" are listed as Single Pole reed switches, which one do I need for the top switch?

Thanks again for your help

Zeb


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 19 Jan 10 at 08:13
Hi Zeb
 
Glad it helped
I had the same problem on mine I replaced the faulty sw't only to damage the other putting back together as they were so fragile.
 
Top is single pole
Bottom double ploe
 
I do have a spare set if you can't get hold of any.
 
 
Cheers


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Posted By: Zeb
Date Posted: 19 Jan 10 at 19:25
Hi sbbfuk

I owe you one already for sending the resistors !

Both part numbers are available from RS but I am not sure which one I need. On the picture in your earlier post you show the packets they came in so I checked the numbers and don't know which to order as they both seem to be single pole switches but a slightly different diameter. I think the picture on their site is a generic one so was no help.

If you can confirm which one I need to order for the upper switch I would be grateful, they both seem to be available and will only cost a couple of pounds. As they are reasonably priced it would be useful if you have a record of the part numbers for both and I will order them just in case I manage to break one when putting the sensor back together.

Cheers

Zeb


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 19 Jan 10 at 20:42
Top is SP RS229-3692
Bottom DP RS394-428
 
Smile


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Posted By: Zeb
Date Posted: 19 Jan 10 at 22:43
Thanks, they were the numbers I took from your photo's, I was not sure though as when I looked them up they are both listed as single pole, am I mistaken or is their listing wrong ?

Cheers

Zeb


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 20 Jan 10 at 08:01
Hi Zeb
 
I still have some here in their bags so took the numbers from them, the photo RS shows on their site is of a SP even for a DP.
The offers still open if you want me to send the set I have.
 
Cheers
G


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Posted By: Zeb
Date Posted: 20 Jan 10 at 11:29
OK then please do send me a set if you have them going spare. I checked their site and it is UK delivery only or I need to register and order from the French site, that will be a pain in the arse for me.

I appreciate this and would at least like to give you a couple of pints, so if you have a PayPal account PM me your e-mail address and I'll cover the cost of a couple of beers.

Thanks again

Zeb


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1990 Westfalia California 1.6TD


Posted By: Nugget
Date Posted: 18 Feb 10 at 23:25
Any idea where Lagerheads depth gauge thread can be found? I've done loads of searches on Club 80-90 and clicked the link but can not find anything.


Posted By: Zeb
Date Posted: 19 Feb 10 at 15:55
I don't think is is there anymore, look at the previous page on this thread as the text has been put here but without the pictures. I don't think you will need anything else.

Cheers

Zeb


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1990 Westfalia California 1.6TD


Posted By: Holydiver
Date Posted: 02 May 10 at 22:05
Hi Nugget
 
I've got it saved as a word doc PM me your email add and i'll sending to you


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Posted By: O===vw===O
Date Posted: 06 May 10 at 23:15
take a look at this one £24 from gunzl - http://server2.gs-shop.de/200/cgi-bin/shop.dll?SESSIONID=00887388153932989&AnbieterID=4357 - http://server2.gs-shop.de/200/cgi-bin/shop.dll?SESSIONID=00887388153932989&AnbieterID=4357

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life moves pretty fast,if you dont park the T4 and take a look around once in a while,you could miss it!

03 2.5tdi 88 with decat, egr blank, big injectors, stan intercooler, remap apparently 130bhp


Posted By: grm2507
Date Posted: 06 May 10 at 23:39
I bought one of these a while back and never used it (managed to resell on ebay).  It doesn't look that straightforward to fit and certainly isn't a direct replacement for the original sensor.

I managed to get a direct replacement for the original item from BusDepot.com in the US.  A bit pricey but so simple to fit - and worked first time.  Trouble is that I may have got the last one available made by their supplier (I always believe what they tell me!!) - worth checking though.


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1987 Vanagon GL DJ 2.1 - Dove Blue Metallic

1991 Westfalia Atlantic JX 1.6TD (Pop-top) - Alpine White


Posted By: Zeb
Date Posted: 07 May 10 at 21:48
It really is a simple repair if you have a soldering iron and are able to buy the resistors and reed switches locally. It is much more satisfying to repair/restore the original Westy kit instead of spending loads of cash on aftermarket kit.

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1990 Westfalia California 1.6TD


Posted By: grm2507
Date Posted: 07 May 10 at 22:23
Yep - I can appreciate that.

My problem was that I had absolutely nothing to work with.  Whoever had the bus before me had taken everything out.

I know I could have got the tube, fixed it to something in the tank lid, got the resistors/reed switches and fixed them to something I could shove into the tube etc. etc...

Not sure I have that much time or inclination.  I'd rather be out using the damn thing!Wink

Mucho respecto for those that do build the things themselves though.


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1987 Vanagon GL DJ 2.1 - Dove Blue Metallic

1991 Westfalia Atlantic JX 1.6TD (Pop-top) - Alpine White


Posted By: Zeb
Date Posted: 07 May 10 at 22:52
Ah I agree that's a little different than replacing the switches. Try Spannerboy on here for a used one then repair if you have to.

Is the pump still in the tank and connected with two spare spade connections for a sensor if you can find one?


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1990 Westfalia California 1.6TD


Posted By: dbeierl
Date Posted: 07 Aug 10 at 04:45
Originally posted by sbbfuk sbbfuk wrote:


It appears to me that these sender units quite commonly fail for 2 main reasons:
a. the plastic rod leaks and takes on water which causes corrosion and deformation of
the copper strip.
b. the magnetic reed switches break (probably because the rods get bent or they are
made to bend due to water getting in and so causing the double sided copper clad
"rod" to bend)
NOTE- these rods are actually VERY fragile, so NEVER try to straighten a bent
one - this is what breaks the glass reed switches!

The leakage failure is mostly because this is a very high-impedance circuit (it's pulled up to +12v through a 1-megohm resistor.  Water soaks into the edges of the PCB and shorts the foils together.  The tipoff for water damage (generally fixable by running several changes of neutral grain spirits through) is that the LED reading may change after the switch has been on for a few minutes.

The breakage failure is purely because the blighters who did the soldering didn't leave any slack in the leads.  Resolder them with a bit of slack and it will stop being so infernally delicate.


Posted By: Holydiver
Date Posted: 22 Sep 10 at 13:48
Seeing that over 1,300 please have read this post I take it that a lot of you have an issue with your sensor??
 
Since posting this thread I've been thinking about making these, but wonder if there's a market for it??
 
If you think there is PM me and if I get enough I'll look into this again
 
Cheers


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Posted By: cooky73
Date Posted: 26 Sep 10 at 20:56
I would but a T4 one if it was cheap - Gunzl wants €130!

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2003 Westy California TDi


Posted By: Holydiver
Date Posted: 23 Feb 12 at 13:38
Now available if you're interested please PM or email wedgewerks@btinternet.com


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Posted By: Zeb
Date Posted: 28 Jun 12 at 21:21
Top quality replacement, I Just fitted one of these after repairing my own a couple of times from the earlier post.

I'm not usually in a hurry to chuck out any original parts but it seems to be far more robust than the original.

Great job Holydiver Thanks very much

Zeb


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1990 Westfalia California 1.6TD



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