Water pump running dry

David Guthrie

David Guthrie

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Joined
Oct 21, 2016
Posts
63
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Northumberland
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45,710
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Fiat Ducato Hi-Top
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When we drive with the 12v system on (for the fridge) the water pump runs. The van used to have a permanent under-slung tank, now replaced with a tow bar.
I'm a bit concerned about the pump running dry for extended periods.
Try as I might, I can't get at the pump (or trace the power lead run) to introduce a switch into the system.
Two things:
1) Is it a big deal that the pump (make unknown since I can't get at the beggar) runs dry for extended periods
2) Is there a way to get at the lead from the Zig panel?
I realise this is a bit of a 'hail mary', but ...
 
The pump is running because it's searching for water due to a pressure drop as a result of no water in the system (If I have read your post correctly). This is not good but I fail to understand why you have no water tank and hence no water ? Anyway, it's not good to let the pump run dry for extended periods and find it odd you are unable to access it. Anyway, not to worry it will be protected by a fuse, so just pull the fuse in your fuse board assuming you have one.
 
Thank you @PhilandMena Ah! Yes, you assume correctly. The water tank is portable, so only put under the van while we're parked up, hence the pump's trying to upload water to no avail.
I did try removing the fuse identifies as 'pump' - it made no difference!
Ah, the joys!
I think maybe I'll have to take the front off the control panel and see if there's a way of doing it. On the control panel, incidentally, there are no switches (it's an old van) just the fuse holders.
Many thanks for your swift response.
David
 
@PhilandMena - As to access, the pump's built in behind woodwork (which I'd have to cut to gain access - and even then, I'm not sure it's where I suspect it is!
As I said, 'Ah, the joys!'
David
 
As the tank has been removed it obviously isn't a submersible pump but a diaphragm pump.
These pumps can run dry as there is no spinning impeller.....but I wouldn't let it run for hours on end.
As it is a diaphragm pump it has to be somewhere in the van.
See if you can trace pipework back from the sink or from the water barrel inlet point.
It may be under seating or even under the wardrobe floor......it has to be somewhere accessible.
You could try pulling different FUSES to see which one controls it.....just because the legend says its No ? Doesn't mean it is and it does need fusing.

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@pappajohn
Ah, yes! I'll try all the fuses as you suggest.
On access, yes, it could be any old where. I'd already dismantled a cupboard to get at the water heater. Might just do that again and see if it's lurking in there - but it sounds like it's behind a glued-in panel near the sink. I guess I'll have to take out the sink and have a peek down there.
Maybe I'll just buy a coolbox ....
 
Well, @pappajohn and @PhilandMena , I managed to find the wire feeding the pump, having dismantled the cupboard behind which the heater lies, so will install an in-line switch. In fact, the control panel does not have a fuse marked 'pump' (false memory), so I couldn't try the process of elimination.
The trouble is ... I don't know whether that line also feeds the fridge. The cabling disappears down a hole drilled in the floor of the cupboard; oh joy. We'll know when we get wherever we're going and find the butter in a puddle I suppose. If only the bloomin' fridge had a wee red light on it to indicate it was on!
Anyway, the dry-running pump problem is solved.
Many thanks for your contributions.
 
Hello, @Gellyneck . Nope, never did as far as I can recall. I'll run a cable out to keep the batteries charged, then run the fridge on battery and wait for the chill in the freezer compartment!:)
 
David Guthrie said:
Hello, @Gellyneck . Nope, never did as far as I can recall. I'll run a cable out to keep the batteries charged, then run the fridge on battery and wait for the chill in the freezer compartment!:)
Click to expand...
and I though I was the king of the bodgers :notworthy2:I am not worthay:rofl:
bill

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Ah, no, @Wildbill. I am the Plastic Padding Potentate! Just been bodging a slightly loose front fender. Takes me back to me old car-owning days. Acres of aluminium mesh. Then there's Gun-Gum ...
 
David Guthrie said:
Ah, no, @Wildbill. I am the Plastic Padding Potentate! Just been bodging a slightly loose front fender. Takes me back to me old car-owning days. Acres of aluminium mesh. Then there's Gun-Gum ...
Click to expand...
I have fund stekaflex and mille putty epoxy putty grate bodging material
bill
 
David Guthrie said:
Hello, @Gellyneck . Nope, never did as far as I can recall. I'll run a cable out to keep the batteries charged, then run the fridge on battery and wait for the chill in the freezer compartment!:)
Click to expand...
Your fridge shouldn't run on 12v except when the engines running.
But it sounds like that fella Mr Bodger has been fiddling so any things possible I suppose.
 
Well, I've learned summat new, @pappajohn ! Never knew that. Ah, well, we'll see if Mr Bodger's gone a bodge too far!

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David Guthrie said:
Well, I've learned summat new, @pappajohn ! Never knew that. Ah, well, we'll see if Mr Bodger's gone a bodge too far!
Click to expand...
The 12v fridge supply is taken from the engine battery via a 30amp automotive relay.
The relay is triggered by the alternators D Terminal (the thin wire) when the engine is started.
Turning off the engine cuts power through this wire so the relay disconnects cutting the 12v supply to the fridge.
There, you just learnt how it works.
 
Whilst positive displacement pumps will run dry for a while it will not improve their longevity. It would be a good idea to firstly find out where the pump is and how to get into it, and to carry a spare pump.
 
Wise words, @maxi77! Unfortunately, short of dismantling the carcass of the area where I suspect it is, I think that'll be for another day. In the meantime, I've isolated the wire feeding it and inserted a switch in the circuit. As mentioned earlier, we'll now find out whether I've also isolated the fridge! (I've checked: there is no helpful little light in it that indicates that it's on); but I have a longish run to do today to pick up a little trailer, so I'll find out soon enough.
As to a spare pump ... I think it'll be a bucket!
David
 
WHEN you find the pump it may be worth moving it to an accessible location for future repairs...they don't last forever and the cost of a bit of pipe and couplers is minimal compared to a strip out again.

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Very true, @pappajohn . Since we're off on our travels to France next week, it'll be a job for when we get back and it won't matter that I've hacked the galley to bits.
The other job I have lined up is to replace the existing 240v feed and RCD box. There's one in the van, but it's only rated at 3 amps, as far as I can gather; at least, that's what it says on the one and only socket!
Another thread, methinks.
 
Aye, I'll do that. It'll be after we get back from our trip to la douce France (off on the 18th). Can't wait to get back and start dismantling the galley to get at the bugger!
I'll be looking at replacing the existing 240v RCD next - it seems to be rated at 3 amps; well, that's what it says on the socket. Oooh, these old vans!
 
David Guthrie said:
Wise words, @maxi77! Unfortunately, short of dismantling the carcass of the area where I suspect it is, I think that'll be for another day. In the meantime, I've isolated the wire feeding it and inserted a switch in the circuit. As mentioned earlier, we'll now find out whether I've also isolated the fridge! (I've checked: there is no helpful little light in it that indicates that it's on); but I have a longish run to do today to pick up a little trailer, so I'll find out soon enough.
As to a spare pump ... I think it'll be a bucket!
David
Click to expand...

One problem with positive displacement pumps is they are noisy, the noise is a form of water hammer and thus is transferred along pipes so the loudest noise may well be where the pipes touch a sounding board rather than where the pump is. It may well be worth trying to trace the piping, not easy I agree but it may save you hair when things go tits up.
 
Looks like I'll have to take the sink out. Rusty screws. Oh joy!
 
Wise man, @maxi77 ! I used to have a boat, so I have boxes of stainless bits and bobs I didn't think I'd need again. I also had a really nifty box of electrical connectors and tinned 12v cable. Alas, no longer with us. Live ... learn!
 
Always carry a spare water pump, I can hear it now "Darling I'm sorry you can't have a shower or wash your hair because the pump has gone phuttttt ". :pray:
 

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