Diesel lift pump

[MoominPapa]

When we bought Melaleuca, there was a rotary vane pump for filling the day tank. This had two problems, it leaked a like a sieve, and it frequently didn't work at all, if it wasn't primed. It was necessary to undo the pipe union and pour some diesel in to get it seal and prime.

 

To fix this, I've bought a new semi-rotary pump, these seem to be the standard solution for this problem. Guess what it, doesn't prime either! Once full of diesel, it pumps like a good-un, but leave it for a few hours and the diesel drains back and it won't work again. PaddingtonBear of this parish has what looks externally like exactly the same pump: it's lifting higher than mine, and works perfectly. He says it stays primed for weeks.

 

The pump is lifting from a tank at bilge level, the pipe comes out through the top of the tank and (I assume) has a dip-tube to the bottom, the pump is about 18 inches higher than the bottom of the tank, and is discharging into a day tank another couple of feet up.

 

Have I just got unlucky and bought a duff pump, or could there be another problem I've missed?

 

Bah.

 

MP.

[Timleech]

When we bought Melaleuca, there was a rotary vane pump for filling the day tank. This had two problems, it leaked a like a sieve, and it frequently didn't work at all, if it wasn't primed. It was necessary to undo the pipe union and pour some diesel in to get it seal and prime.

 

To fix this, I've bought a new semi-rotary pump, these seem to be the standard solution for this problem. Guess what it, doesn't prime either! Once full of diesel, it pumps like a good-un, but leave it for a few hours and the diesel drains back and it won't work again. PaddingtonBear of this parish has what looks externally like exactly the same pump: it's lifting higher than mine, and works perfectly. He says it stays primed for weeks.

 

The pump is lifting from a tank at bilge level, the pipe comes out through the top of the tank and (I assume) has a dip-tube to the bottom, the pump is about 18 inches higher than the bottom of the tank, and is discharging into a day tank another couple of feet up.

 

Have I just got unlucky and bought a duff pump, or could there be another problem I've missed?

 

Bah.

 

MP.

 

Fit a foot valve on the bottom of the pipe.

 

Tim

[koukouvagia]

I use two of these pumps – one for the day tank on the motor and one for a diesel tank for the Refleks heater on the butty. You’ll see that the the pipewok curves upwards in both cases and neither pump drains because the fuel would have to travel uphill.

I did wonder if the fuel would siphon back into the tanks, but that doesn't happen and both pumps remain primed the whole time.

 

 

Edited January 1, 2009 by koukouvagia

[bargeeboy]

It looks like a proper boat

 

What is it?

 

Oh and as stated put a stop cock under the pump will stop it draining back when not in use

[MoominPapa]

Fit a foot valve on the bottom of the pipe.

 

Tim

 

You mean like this: Ebay clicky (I love the interweb: 'till today I'd never even heard of a Foot Valve. Now I can buy one!) I'll need to look hard at the fittings on the tank to see if I can get it in. Would a non-return valve in the pipe just above the tank take-off work as well? That would be easier to fit.

 

MP.

[koukouvagia]

It looks like a proper boat

 

What is it?

Top pic Hampton, bottom Owl.

[Timleech]

You mean like this: Ebay clicky (I love the interweb: 'till today I'd never even heard of a Foot Valve. Now I can buy one!) I'll need to look hard at the fittings on the tank to see if I can get it in. Would a non-return valve in the pipe just above the tank take-off work as well? That would be easier to fit.

 

MP.

 

Yes. Or an ordinary non-return valve.

 

A non-return valve just below the pump would certainly help, but not as good. The other way is a shutoff valve below the pump, turn it off after use & it should hold the pump full of fuel.

 

Tim

[OptedOut]

I have one of the "barrel" pumps, I fitted a filter and NRV before the pump and it works OK, the only thing I can add is that the pump is self priming anyway. (NRV is not 100%).

 

[NB Alnwick]

I use two of these pumps – one for the day tank on the motor and one for a diesel tank for the Refleks heater on the butty. You’ll see that the the pipewok curves upwards in both cases and neither pump drains because the fuel would have to travel uphill.

I did wonder if the fuel would siphon back into the tanks, but that doesn't happen and both pumps remain primed the whole time.

 

We have two similar pumps on 'Alnwick' the smaller one is used to pump diesel from the main bilge tank into the 4 gallon (18 Litres) day tank via a 3/4" pipe - it has always worked fine and has never needed priming - even after I inadvertently sucked the main tank dry on the way back from the IWA festival at St. Ives last year.

The large one is set up as a bilge pump sucking water out of the cabin and engine room bilges via a 2" pipe. We only needed it once when the domestic water pump leaked gallons of fresh water into the cabin bilge and whatever we tried we just couldn't get it to work - in the end we pumped the water out with a hose connected to the inlet side of our sludge gulping shower drain pump. It would be nice to get the large one working - just in case.

 

Does anyone know where we can obtain service parts and maintenance instructions?

[koukouvagia]

Does anyone know where we can obtain service parts and maintenance instructions?

 

These people are very good for rotary pumps which are about half the price of pumps elsewhere. Their website appears to be down at the moment, but the details are:

W Robinson & Sons (EC) Ltd, 35-41 Fowler Road Hainault Industrial Estate Ilford Essex IG6 3WR

Tel :020 85596000

[OptedOut]

Pretty handy diagram here.

 

http://images.google.co.uk/imgres?imgurl=h...l%3Den%26sa%3DN

[LEO]

Top pic Hampton, bottom Owl.

Hi,

 

I have a similar pump to KooKoo's and it did need priming each time when I bought the boat, but I tightened all the nuts and got the joints properly sealed, now it does take some 'action' with the handle to draw the diesel up from the tank before some reistance is felt and then she 'pumps like a good 'un'.

 

As an aside we had these pumps to pump water in a house when I was young, it became defective and my brother and I 'overhauled' it - the pump incorporated a leather washer which the dog ate - took us a few days following the dog round - but we got the washer back - nice and supple if I remember right.

 

Leo.

[Proper Job]

MP

 

A happy New Year to you

 

Ocelot has a semi rotary lift pump. Like yours, it drains back in to the main tanks between use.

 

Unlike yours, half a dozen strokes and it primes it self and we're away pumping up to the day tank.

 

I would recommend to courses of action suggested.

• Make sure every thing is tight (mine stiff to operate until it primes and the fuel lubricates the pump)
  
• Fit a non return valve in the line
  

 

The other alternative is to paint yours the same colour as PB's and swap them over after to much of the falling down nectar is imbibed one evening (only kidding )

[MoominPapa]

MP

 

A happy New Year to you

and to you.

Ocelot has a semi rotary lift pump. Like yours, it drains back in to the main tanks between use.

 

Unlike yours, half a dozen strokes and it primes it self and we're away pumping up to the day tank.

 

I would recommend to courses of action suggested.

• Make sure every thing is tight (mine stiff to operate until it primes and the fuel lubricates the pump)
  
• Fit a non return valve in the line
  

I'm pretty confident that the pipework feeding the pump is tight, and I've tightened the gland around the pump shaft - no improvement.

 

I think the NRV solution is the one to go for: I'll order one ASAP.

The other alternative is to paint yours the same colour as PB's and swap them over after to much of the falling down nectar is imbibed one evening (only kidding )

 

Given my luck with these things, I'd find that the secret of PB's success is a foot valve that he doesn't even know he has.

 

MP.

[MoominPapa]

Just to finish this off, I've solved the problem. I did two things: I tightened the gland nut on the diesel shut-off gate valve in the suction line. I don't think that was a problem, but it may have been. Secondly I found the right technique for priming the pump. The trick is to pump very fast, but over a limited arc. It's not possible to pump fast enough over the whole travel of the lever without smashing into the end stops so hard that something is likely to break, but by "waggling" the lever over the central two-thirds of it's travel as fast as possible it's possible to extract air from the suction line faster than it leaks back in, and prime the pump. Once it's primed it works fine and steady strokes over the whole range of lever movement work a treat.

 

As usual, it ain't what you do, it's how you do it wot counts.

 

MP.

[Timleech]

Just to finish this off, I've solved the problem. I did two things: I tightened the gland nut on the diesel shut-off gate valve in the suction line. I don't think that was a problem, but it may have been. Secondly I found the right technique for priming the pump. The trick is to pump very fast, but over a limited arc. It's not possible to pump fast enough over the whole travel of the lever without smashing into the end stops so hard that something is likely to break, but by "waggling" the lever over the central two-thirds of it's travel as fast as possible it's possible to extract air from the suction line faster than it leaks back in, and prime the pump. Once it's primed it works fine and steady strokes over the whole range of lever movement work a treat.

 

As usual, it ain't what you do, it's how you do it wot counts.

 

MP.

 

I expect you know this, but if your pump does need priming you should be able to remove a small plug in the front face (some new imports might not have this, not difficult to add though) and give two or three squirts of oil with an oil can & replace the plug, it ought then to work as the lub oil will help to seal the valve faces. Much easier than messing about trying to get diesel into the top, and the lub oil will do no harm.

 

Tim

[Proper Job]

I expect you know this, but if your pump does need priming you should be able to remove a small plug in the front face (some new imports might not have this, not difficult to add though) and give two or three squirts of oil with an oil can & replace the plug, it ought then to work as the lub oil will help to seal the valve faces. Much easier than messing about trying to get diesel into the top, and the lub oil will do no harm.

 

Tim

Good tip Tim

 

I actually prime mine in the way that MP describes (I didn't realise it was in the method - I just do it that way). Mine screams like a scalded cat until the fuel gets to it and I know its not doing the mating faces any good.

 

I only have a problem when its left for a few days. When used every 24 hours a couple of strokes and its fine.

 

I'll try the lub oil trick in future

[Strads]

Ok.. on a related theme,,

 

I have just installed the hand pump we gained with the boat (unfitted - along with the fuel day tank)

 

it primed fine - but then sprayed fuel out from just about every where!!..

 

the main leak points are the two flanges that are screwed tight by the 2 bolts - i had to remove two cardboard blanking washers and the used the red coloured diesel sealing gunge (used on the other joints ok) and screw tight -

 

now eau de diesel in the boat - almost as good as wd40,,,

 

My Question - point for clarification did you have to use additional washers - seals? ifso what sort ? copper / neoprene ???

 

Also does any one know stockest of fittings for them for 3/42 thread to 3/8 or even 5/16" - as the only ones I could find where to 15mm then to to 10mm(3/8)

which means lots more joints

 

 

 

Second question - is it smart/sensible to also leave the mechanical fuel lift pump in place also supplying the day tannk.

 

Thirs question -- ( I know - pushing my luck) the "breather" / fuel return pipe - will that when connected to the tank retrun pipe be sufficient to allow teh day tank to be "filled"...?

 

 

over to the techies...