More Duetto Pump Problems

We have just had our first full week away with our 96 Duetto I was not shure how long a tank of water would last so I asumed that when the pump ran constantly it was either low on water or we had a leak. As a matter of intrest I turned on one of the taps and water came out. When I turned the tap off the pump stoped running. It was the same when we turned the hot or cold tap on. If it is a leak the pump would re-start after a while but it only keeps running after you have run the water. My first thoughts are the switch but I think some outside thoughts from you nice people before I go susing and bogling.

The pump contains a pressure operated switch in the supply to the motor.

When you fill the tank and boiler with water you use the pump to fill the pipes and push out the air. When water is running freely from both hot and cold taps you close them. Pressure builds up instantly in the pipe system and the pressure switch disconnects power from the pump motor. The pump stops.

When you open a tap the pressure reduces and the pump motor starts and keeps going till you close the tap gain.

I hope that is clear.

Peter

Thanks Peter. I get what youre saying but this is not quite what happens. As I tryed to describe the only way to stop the pump running is to re-open a tap, you get a splutter of water then it runs clear, then when you turn the tap off again the pump stops as you say it should do. I asume the fault must be in the switch. If so were is it and what sort of a job will it be to change it. I am an ex PSV fitter so am I used to things being fitted in daft places that were accesable before the body was built.

What you describe is typically consistent with there being insufficient water at the pump for it to pump through, not (typically) a fault with the pressure switch. It may be that the filter assembly - which screws onto the inlet side of the pump - is cracked and letting in air, which the pump cannot push through easily.

When you find the pump, take a close look at the filter (which should have a clear body) and see of there is any sign of air entering there. They are known to crack if not carefully drained down for the winter and ice expands inside them.

Dave 418 wrote: ............... the only way to stop the pump running is to re-open a tap, you get a splutter of water then it runs clear, then when you turn the tap off again the pump stops as you say it should do. I asume the fault must be in the switch. ............

Hi there,

It probably isn't the pressure switch.

The "spluttering" is a big clue! Either the water level is low or air is getting into the system some other way.

Have you left the pump switched on when you have been motoring? If so then it is possible that the water has slopped below the level of the pump suction and air has entered the system.

My suggestion is to fill the tank to the very top, run the pump until you get steady flow and then close the valve. If you can't get steady flow then air is getting into the suction from somewhere and you need to check the pipework.

If you get steady flow and the pump doesn't stop when you close the valve then the pressure-switch may be the culprit OR the pump diaphragm may need replacing.

Hope this helps.

Best regards,

many thanks folks. This gives me some ideas to play with. If the filter is cracked my logic thought is why isnt it leaking water. I have had a quike look at the pump area to see where is mounted and it apears dry. Air ingress with no leaks isnt unheard of on Diesel fuel systems and are a pig to find. If this filter is the culprit I asume this is a seperate item from the pump. If so were would I get one from. Another odd thing I forgot about. One morning I realised I hadnt turned the pump off the night before because it started running at exactly half seven in the morning. Being on managements side of the bed she wasnt too pleased and demanded a brew in bed. Any way I have some thing to play with now. Next trip will be two weeks in Europe late June.

Dave 418 wrote: If the filter is cracked my logic thought is why isnt it leaking water.

Because it's on the inlet side. When the pump is running there's negative pressure there so it pulls in air. When it's not it has the wieght of a column of water to the tank, so it pulls in air until the water column drops back down.

If the pump is a Shurflo (almost certainly will be) then the filter body is readily available separately and just screws on.

Dave 418 wrote: Thanks Peter. I get what youre saying but this is not quite what happens. As I tryed to describe the only way to stop the pump running is to re-open a tap, you get a splutter of water then it runs clear, then when you turn the tap off again the pump stops as you say it should do. I asume the fault must be in the switch. If so were is it and what sort of a job will it be to change it. I am an ex PSV fitter so am I used to things being fitted in daft places that were accesable before the body was built.

Thanks for the clarification. I have a pump in the garage that exhibited exactly those characteristics. It had a minute air leak into the pump chamber. It took a long time to find and when it was, what could be seen was a tiny bubble develop for an instant at the joint between the two halves of the pump when the tap was closed.

When I dismantled the pump I could see no sign of a fault in the joint but I smeared the joint with the slightest amount of sealant and re-assembled it. Its worked perfectly since - every time I use it to drain the garden pond!

Peter

Right folks I think we have progres of a sort. This is just like working on buses, clip facing just in the wrong position and the pipe is kinked. Once I had a bit of a swear the clip loosen and I tryed to ease the pipe off the filter. Not me being ham fisted but the stub for the hose broke off the filter as soon as I touched it. This could be a scorce of air getting in if it was cracked. The route of the pipe was a bit strange and as I said the pipe was kinked quite a bit. I had to trim a bit off the hose because I couldnt get the old stub out were the pipe is. When I re-routed the pipe to get rid of the kink there is plenty of pipe the to fit back on. New filter ordered and we will see what happens next. This must be an ill omen because I have domestic warfare this weekend. I have the tap to change in our kitchen I like many others dont mind playing with mechanical things but domestic repairs I hate because they hate me by going wrong.

This is exactly what happened to me, the new filter housing sorted it out.
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I had a quike look for anything in the forum relating to my problems and missed youre artical some how. Now I recognise the filter you talked about. I was looking for a black cased filter as per the spares list in one of the adverts for sureflow pumps. The place I eventualy found a filter is just down the coast from me so it shouldnt take postman pat long to get it here. So far our Duetto minor faults havnt put me off so as long as I can keep on top of these I think it has been a good choice for a first van. Next little chalenge is to find a replacement mug. One of the set that came with the van the handle has fallen off. A minor superglue job for now.

Got the new filter fitted today. Not as simple as it sounds. Pipe just long enough and very hard due to its age and a two hands in the back of the cupboard to get it on with the help of a bit of washing up liquid. Now the pump shuts off when it should do. Whilst I had my head in the cupboard checking for leaks whith pump running Inoticed that as the pump shut off there was a pin head size buble apeared at the joint near the base. I asume this is were the diaphram sits. As I havnt got time to take the pump out before we go away next month I will have to risk it rather than stripping the pump. I can see it involving changing pipes as well due to there age. It must be nice to own a newer van that you can sit back and not need to play with.

Dave 418 wrote:................. It must be nice to own a newer van that you can sit back and not need to play with.

Ah, but the problem then is that it is so new you are scared to dive in yourself in case you do more damage!

Plus, by the time everything is A1 on the old van you will have the confidence to go anywhere in the knowledge that you can fix whatever goes wrong.

With regard to "chancing it" with the tiny leak be reassured that leaks NEVER cure themselves; but hope for the best and remember that there are caravan accessory shops all over Europe! (Also check out the motto below!)

Best regards,

Dave 418 wrote: It must be nice to own a newer van that you can sit back and not need to play with.

The more I read through the problems that members on here have with "newer" vans, the more I'm glad I have an older one. Vans that are so clever, they lock you out of your own van and you need a secret key to get in, vans that have immobilisers which need special data cards & keys which cost a fortune when they go wrong at best or £1000 for a new one at worst. Engines that need a particular grade & make of oil or they threaten to self destruct etc..etc..etc..
I'll keep my '95 petrol Symphony thanks

Frank

Hi Dave

Read again my post of May 8. It is exactly the fault I describe there. The fix I describe should work but if it was my van I would replace the pump. In your current circumstances I would get a spare to keep with me while away so if it failed completely it could be replaced but otherwise just replace when I had time.

Peter

Hi Dave.

I would not worry to much about this small leak. Best to repair it when you can though. As you have identified it needs a new diaphragm.
The only problems you will encounter with such a small leak will be the taps tend to spit when first turned on. Ohh by the way after you have taken out your pump to repair it don't screw it down to tightly when refitting it. this tends to make them quite noisy.

Good luck. Whisky.

Thanks folks, yes I agree about newer vehicles. I worked at the roadside for 22 years and it got so I was fixing less every day. My old timer boss couldnt get why our fix rate was going down with new vehicles. Regarding my pump I am going to chance it for now. I realy dont fancy disturbing the pipes that are on there. My time on old buses taught me not to disturb old pipes unless you are ready to replace them. Just let me get to the point of thundering down the A1 and I will only look foward to our time away not look for faults.