Guest Posted May 29, 2010 Share Posted May 29, 2010 This is something I feel I ought to know, but don't want to get it wrong ... On a boat I'm working on, the domestic water pump has stopped sucking, following the tank unexpectedly running dry. The tank is now full and the pump is running, but not drawing water - all the taps are dry. It looks like quite an old pump (pics below) and I guess not self-priming. I know very little about this, and everywhere I've looked on the net tells me (somewhat obviously) that I need to prime the pump, but without clearly explaining how. I'd be really grateful if someone could kindly explain the priming process in simple steps. Quote Link to comment Share on other sites More sharing options...
Palmtree Posted May 29, 2010 Share Posted May 29, 2010 Hi, Is the pump lower than the tank? The filter beside the pump is there water in it? You might have an air lock in the system, if so try just cracking the brass nut beside the pump and let the air out. Ian Quote Link to comment Share on other sites More sharing options...
Palmtree Posted May 29, 2010 Share Posted May 29, 2010 Hi, Thinking about this I made the assumption the brass nut fitting is on the inlet side of the pump, it is the inlet side you need to get the water into. Does the water pipe come out of the bottom of the water tank or the top? Ian Quote Link to comment Share on other sites More sharing options...
Guest DAYTONA-BILL Posted May 29, 2010 Share Posted May 29, 2010 I would have thought the feed pipe from the tank would come from the bottom, with the pipe inside the tank having an extra length so as to allow "sludge(?)" to lay below the outlet, like in a cars fuel tank. If the pump is lower than the tank, i`d have thought it would be fed by gravity to assist self priming, though i could be wrong. It`s also worth considering if this is an OLD pump, and it`s been allowed to run dry, the internal impellor could have been destroyed, or, as in the case of one of my previous outboards, the rubberised impellor broke free from the centre keyed brass collar. The blades were intact, but the centre was spinning without the blades. Regards ................... Neil. Quote Link to comment Share on other sites More sharing options...
Guest DAYTONA-BILL Posted May 29, 2010 Share Posted May 29, 2010 I know this might sound like i`m taking the arthur, but is there a stop tap on the tank outlet/pump inlet pipe, so you don`t lose all the water when you disconnect it?. If so, check to make sure it`s in the "on" position. This has happened to people before . Regards ............... Neil. Quote Link to comment Share on other sites More sharing options...
Palmtree Posted May 29, 2010 Share Posted May 29, 2010 Neil, I agree the pump looks lower than the tank, and therefore expect gravity will prime to the pump. This is why I suggested bleeding the air if there is an airlock bend in the pipework where the pump is. The pump is a diaphragm type pump so it will not have a rotating vane but a rubber disc moving in and out and a set of valves, these needing the water to be fed in on the inlet side to prime the pump. I suspect the pipe on the water tank needs to be disconnected and a jug or two of water poured down the pipe to fill the pump. Ian Quote Link to comment Share on other sites More sharing options...
C.Ricko Posted May 29, 2010 Share Posted May 29, 2010 It should self prime, if it is refusing to, undo the filter, (it comes apart in the middle) and wait for the water, put it together and turn it on. I assume the taps are all open? Quote Link to comment Share on other sites More sharing options...
Guest Posted May 29, 2010 Share Posted May 29, 2010 Thanks everyone! I'll check tomorrow, but yes, I'm sure the pump is lower than the bottom of the tank. I'll apply your collective wisdom and have a fiddle. Bruce Quote Link to comment Share on other sites More sharing options...
jimbo Posted May 29, 2010 Share Posted May 29, 2010 Bruce, Another thought, I wondered if when the tank ran dry, it filled the filter and pump with crud? I may be wrong, but looking at the colour and type of pipe on either side of the pump, the filter looks to be on the exit side of the pump?? In which case the pump could very well be full of gunk Quote Link to comment Share on other sites More sharing options...
Guest Posted May 31, 2010 Share Posted May 31, 2010 Quick update - by following the advice on here it was dead easy. I tried Ian's first suggestion initially, so slackened off the nut on the inlet coupling until a little bit of water ran out of the joint, re-tightened, opened the taps and turned the pump on - it worked! Thanks everyone for your helpful suggestions. The forum once again demonstrates what a great community it is! Bruce Quote Link to comment Share on other sites More sharing options...
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