Leaking 'seawater' pump

[RuK]

Hi there's a Jabsco 'seawater' pump on my marinised BMC 1.5 engine, for river water cooling, which is now spraying water all over the engine room. Anyone dealt with this before?

 

I've not taken it apart yet, but am wondering whether I can repair it or need to replace the whole thing. The pump (Jabsco 6490-252) is out of production now but can be replaced by their CW403

[saltysplash]

Hi there's a Jabsco 'seawater' pump on my marinised BMC 1.5 engine, for river water cooling, which is now spraying water all over the engine room. Anyone dealt with this before?

 

I've not taken it apart yet, but am wondering whether I can repair it or need to replace the whole thing. The pump (Jabsco 6490-252) is out of production now but can be replaced by their CW403

 

 

Where is the water spraying from?

 

If its from the cover plate for the impeller, it may just be that the impeller is a bit tired and has 'forced' the cover slightly causing the gasket to fail. New impeller and gasket could be all thats required. if anything has gone wrong internally you wont really know till you have a look. Is it mechanical or electric?

 

I assume its still pumping as water is being sprayed, How is the flow from the outfall? if very weak then you may have some form of blockage in the engine cooling system and the pump is forcing water out from the nearest weak spot as it cant get past the block....just a couple of ideas

[RuK]

Where is the water spraying from?

 

If its from the cover plate for the impeller, it may just be that the impeller is a bit tired and has 'forced' the cover slightly causing the gasket to fail. New impeller and gasket could be all thats required. if anything has gone wrong internally you wont really know till you have a look. Is it mechanical or electric?

 

I assume its still pumping as water is being sprayed, How is the flow from the outfall? if very weak then you may have some form of blockage in the engine cooling system and the pump is forcing water out from the nearest weak spot as it cant get past the block....just a couple of ideas

 

Thanks I'll take it apart & have a closer look, i'm guessing it is the impeller and/or seal (is the gasket the seal?). It is mechanical & pretty old. It's still pumping plenty of water through & out the exhaust so no blockage I don't think

[Batavia]

Hi there's a Jabsco 'seawater' pump on my marinised BMC 1.5 engine, for river water cooling, which is now spraying water all over the engine room. Anyone dealt with this before?

 

I've not taken it apart yet, but am wondering whether I can repair it or need to replace the whole thing. The pump (Jabsco 6490-252) is out of production now but can be replaced by their CW403

Certainly worth trying to fix it, given how much they cost new.

 

I have been very impressed by Jabsco's ability to produce key spares (seals, etc.) for very old pumps.

 

There is not much that can go wrong - either something at the impeller end, which an normally be cured by a new gasket and possibly reversing the cover plate if it has become very worn, or at the shaft end, which can normally be fixed with a new seal (and replace the bearings while it is stripped down).

 

The only real problem is if the shaft has become very scored in the vicinity of the seal, but even fixing this properly would probably be cheaper than buying a new pump.

 

Chris G

[KevTheWelder]

I've got a 1960 2.2 litre BMC in my boat with the same setup.Mine started to drip awhile ago,took the inspection cover off&sure enough,as has been suggested,the gasket was just very worn.Put some blue Hylamar gasket sealant on it&all's ok now.On the subject of raw water cooling,I'm in the middle of converting my BMC to radiator cooling.Have found a nice old lorry radiator,just need to weld up some new fittings.I've never personally seen a radiator cooled boat engine,but there must be some out there surely?I've a plenty big enough engine room,with side doors either side,so I'm of the opinion that ventilation won't be a problem?In a way I would've liked to keep the raw water cooling,as my BMC&Newage gearbox,and all fitments,are original,so 49 years old,but the reality is that raw water cooling on the canal just isn't practical in my opinion,there's just too much crap in the canal to block the system.

[ditchcrawler]

I've got a 1960 2.2 litre BMC in my boat with the same setup.Mine started to drip awhile ago,took the inspection cover off&sure enough,as has been suggested,the gasket was just very worn.Put some blue Hylamar gasket sealant on it&all's ok now.On the subject of raw water cooling,I'm in the middle of converting my BMC to radiator cooling.Have found a nice old lorry radiator,just need to weld up some new fittings.I've never personally seen a radiator cooled boat engine,but there must be some out there surely?I've a plenty big enough engine room,with side doors either side,so I'm of the opinion that ventilation won't be a problem?In a way I would've liked to keep the raw water cooling,as my BMC&Newage gearbox,and all fitments,are original,so 49 years old,but the reality is that raw water cooling on the canal just isn't practical in my opinion,there's just too much crap in the canal to block the system.

You may need a BIG fan

[KevTheWelder]

You may need a BIG fan

Well I've a spare 2.2 engine,ex-BMC lorry,so will try the fan blade off of that.Two chances!Will keep a close eye on things,but my logic is that if the same engine didn't overheat under a cramped old lorry cab,it shouldn't in a spacious,well ventilated engine room.

[RuK]

Certainly worth trying to fix it, given how much they cost new.

 

I have been very impressed by Jabsco's ability to produce key spares (seals, etc.) for very old pumps.

 

There is not much that can go wrong - either something at the impeller end, which an normally be cured by a new gasket and possibly reversing the cover plate if it has become very worn, or at the shaft end, which can normally be fixed with a new seal (and replace the bearings while it is stripped down).

 

The only real problem is if the shaft has become very scored in the vicinity of the seal, but even fixing this properly would probably be cheaper than buying a new pump.

 

Chris G

 

Thanks Chris & Kev,

 

I've taken a look & the water's coming out from the impeller end, under the end plate. I'm a novice with engines so I'm afraid I don't know what a gasket is, but when I took the end plate off there was no rubber seal - just metal on metal. Is there supposed to be a rubber seal there? The impeller looks fine - tough, rubbery & flexible.

 

I tried screwing the cover plate back on hard to stop the leak & snapped one of the brass screws. Jabsco have got spares so I'll order some screws & a gasket & see if that stops it. I also emptied out the filter between the seacock & the pump- it was full of silt - & I noticed how rubbish the filter is: it doesn't even cover the whole area which water can pass through, so it's likely plenty of crap could be going through the cooling, & maybe caused the leak by blockage & build up of pressure?

Ru

[Batavia]

I've taken a look & the water's coming out from the impeller end, under the end plate. I'm a novice with engines so I'm afraid I don't know what a gasket is, but when I took the end plate off there was no rubber seal - just metal on metal. Is there supposed to be a rubber seal there? The impeller looks fine - tough, rubbery & flexible.

There should be a very thin, compressed fibre gasket between the two.

 

If the inside face of the end plate is badly scored, you can give it a new lease of life by reversing it. This will give a better seal between the end of the impeller and the plate, thereby improving the pump's flowrate a little, and its delivered head, if that is an issue. If you do reverse the end plate, make a note of the pump Model Number first, as this will get worn off quite quickly (speaking from bitter experience).

 

I would also replace the impeller at the same time.

 

Chris G

[Tony Brooks]

Thanks Chris & Kev,

 

I've taken a look & the water's coming out from the impeller end, under the end plate. I'm a novice with engines so I'm afraid I don't know what a gasket is, but when I took the end plate off there was no rubber seal - just metal on metal. Is there supposed to be a rubber seal there? The impeller looks fine - tough, rubbery & flexible.

 

I tried screwing the cover plate back on hard to stop the leak & snapped one of the brass screws. Jabsco have got spares so I'll order some screws & a gasket & see if that stops it. I also emptied out the filter between the seacock & the pump- it was full of silt - & I noticed how rubbish the filter is: it doesn't even cover the whole area which water can pass through, so it's likely plenty of crap could be going through the cooling, & maybe caused the leak by blockage & build up of pressure?

Ru

 

 

Jabscos will not build up much pressure because the impeller wings just fold back but they do freeze and that bends the endplate.

 

When you take the plate off rub in on a bit of wet & dry held against a window, that will show if it has bowed.