Water pump in tank

[2dandaddy]

Hi
I have a Hymer Mercedes MLT 630 and have a problem with the in tank water pump! After I have travelled a distance the pump hose to tank connection comes off which means the pump pumps water in the tank! Tried a different compression clip but that’s not working either! Could superglue connection to hose but I’ve already changed two pumps( burnt out!) and that would make it difficult to change another one! Any suggestions?

 

[MisterB]

can you check along the length of the hose and find out what is causing enough vibration for it to come off, even when tightly secured? if you can stop/reduce any vibration on the hose then it might help. also is the hose long enough, if it was too shrt, then again it might come off more easily than if it were a bit longer then necessary. try fitting some pipe clips/supports to the hose? i assume the pump itslef is not causing enough vibration that the pipe works loose?

 

[tonyidle]

Change the pipe? It isn't a common problem. You've changed one part so it's reasonable to assume the hose is either an incorrect size or (more likely) has aged.

 

[2dandaddy]

I put it down to bounce! If I hit a bump almost guaranteed to come off! It’s the original hose so should be long enough! Longer hose would allow the pump to sit on bottom of tank but would encourage any silt/ bits to be sucked in!

 

[tonyidle]

The pump should rest on the bottom at an angle that tilts the intake. As I said this isn't a common problem (it's the first time I've seen it mentioned on this Forum).

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[Landy Andy]

From what I understand, your setup is allowing all the weight of the pump to hang on the pipe.

To me that is bad design. The fittings won’t be designed for that. I would either hang pump on string/line to take the weight, or put something on the bottom of the tank, so weight is taken , but it isn’t at the very base of the tank.

 

[peterc10]

The pump has a raised flat bottom for a reason, it should be installed so that it just sits on the bottom of the tank with a slight bend in the water pipe. That is the way the one in my Hymer is. You need to lengthen whatever is holding it off the bottom of the tank. It could be the hose or the power cable.

 

[Lenny HB]

Mine does the same. In the last year its done it at least once on every trip. I've made sure the pump sits on the bottom of the tank, tried warming the pipe to soften it before tightening the clip still does it.
They appear to be using a harder pipe than they used to. It used to be a clear reinforced water pipe. The pipe in mine is black. I m going to replace the pipe with a softer one so it will clamp up better.

tonyidle says it's not a common problem as it's not been mentioned on the forum but it's such a minor problem and only takes a few minutes to fix. A lot of people, me for one don't think it's worth a mention.

I don't know why you are burning out pumps as they normally only burn out when run dry for a long period and the pump only comes on when you turn on a tap.

 

[peterc10]

Mine does the same. In the last year its done it at least once on every trip.

Lenny HB You need to understand that those French speed bumps are designed to slow you down They are not there as a challenge to try get all four wheels off the road at the same time.

 

[Lenny HB]

Lenny HB You need to understand that those French speed bumps are designed to slow you down They are not there as a challenge to try get all four wheels off the road at the same time.

They are not a patch on normal Belgium roads.

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[peterc10]

They are not a patch on normal Belgium roads.

I would agree with you there.

But the roads around our way are trying to get as bad

 

[2dandaddy]

Thanks people! Basically what I was thinking but needed reassurance that I wasn’t the only one with this particular problem! I’ll change the hose to a longer one with more flex so that the compression clip can do its job! Might even roughen up the outside of the inlet pipe to get more grip! Yep! I had noticed the bottom of the pump was raised off the bottom but didn’t think it was sufficiently far enough up! Long story short Lenny! Micro switch in toilet stopped working so they fitted another switch just under the basin!!! Thought that wasn’t a bad idea until until the galley micro switch stopped working
And had to keep switching on at the toilet switch! Inevitably the switch kept getting left on and burnt out the pump(s)! I was told the micro switches were always failing! I have no idea why the wires for the micro switch are so tightly routed in the taps. Tried to take one out and wires stretched! Cheers guys! Good to know there is some useful ideas out there!

 

[Lenny HB]

Micro switch in toilet stopped working so they fitted another switch just under the basin!!! Thought that wasn’t a bad idea until until the galley micro switch stopped working
And had to keep switching on at the toilet switch! Inevitably the switch kept getting left on and burnt out the pump(s)! I was told the micro switches were always failing!

Oh dear.
The microswitches don't fail very often it's normally the wires to them that break as there is not enough play for when the lever turns. The latest Reich taps appear to be more problematical than the older ones.
Also I don't think it's very clever on the later taps, the switch is normally closed and the tap in the off position holds the contacts open, confused the hell out of me when I was repairing one.

I always fit a relay in series with the pump to take the load off the switches. A hangover from when they used to fail regularly in caravans.

 

[2dandaddy]

Add to that your normally open and normally closed relays and you can have some right fun with the switches. The German DIN system numbers help there though! Just need to find a piece of hose and get my problem sorted! Must say though Lenny could not be a***d getting down to the pump to put the hose back on every time I wanted a cup of tea! Bit more than a ‘minor’inconvenience! Happy camping people and thanks again!

 

[Lenny HB]

Must say though Lenny could not be a***d getting down to the pump to put the hose back on every time I wanted a cup of tea! Bit more than a ‘minor’inconvenience! Happy camping people and thanks again!

Normally only happens once on a 6 week trip, might be more often if you use your van in the UK with the state of our roads.

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[2dandaddy]

Could put up with that! (Not the roads - the pump problem!!!)