Raw water pump failed

[davel]

The raw water pump on Iona started dripping a while ago. I took the pump apart and found that the seals had worn a groove in the shaft. After finding that the pump and shaft are obsolete I replaced the seals knowing it would only be a temporary fix and on our recent visit to Kent I took the pump off and had a local engineering firm turn down the part of the shaft where the seals sit from 16mm dia to 15mm dia to remove the groove (after checking that I could get 15mm ID seals).

 

When I stripped down the pump two of the impeller vanes were damaged but I figured some debris had got into the pump at some point.

 

On our return to the boat I replaced the pump and fired up the engine and took the dog for a walk only to notice on my return that there was no water coming out with the exhaust.

 

I stripped the pump again to find that all the vanes on the impeller were completely destroyed.

 

I put my last spare impeller on and tried again this time watching to make sure that the pump was pumping, but still no water with the exhaust.

 

I stripped the pump again and realised that there is a lot of wear at the back of the pump chamber and a small amount of wear to the faceplate.

 

It appears to me that there is now a gap at each end of the impeller and water can get around the impeller my feeling is that this is the problem but my neighbour were we are moored reckons that I should use gasket goo to make sure the faceplate is sealed properly.

 

On Johnson's parts list there is a wear plate available for this pump which appears to be held in place by a pin but I cannot see a pin in the chamber.

 

Has anybody used one of these wear plates?

 

The back of the chamber has ridges in it and no wear where the cam is, would I have to have the back of the chamber machined level so the wear plate is level?

 

Any advice?

[RobinJ]

The raw water pump on Iona started dripping a while ago. I took the pump apart and found that the seals had worn a groove in the shaft. After finding that the pump and shaft are obsolete I replaced the seals knowing it would only be a temporary fix and on our recent visit to Kent I took the pump off and had a local engineering firm turn down the part of the shaft where the seals sit from 16mm dia to 15mm dia to remove the groove (after checking that I could get 15mm ID seals).

 

When I stripped down the pump two of the impeller vanes were damaged but I figured some debris had got into the pump at some point.

 

On our return to the boat I replaced the pump and fired up the engine and took the dog for a walk only to notice on my return that there was no water coming out with the exhaust.

 

I stripped the pump again to find that all the vanes on the impeller were completely destroyed.

 

I put my last spare impeller on and tried again this time watching to make sure that the pump was pumping, but still no water with the exhaust.

 

I stripped the pump again and realised that there is a lot of wear at the back of the pump chamber and a small amount of wear to the faceplate.

 

It appears to me that there is now a gap at each end of the impeller and water can get around the impeller my feeling is that this is the problem but my neighbour were we are moored reckons that I should use gasket goo to make sure the faceplate is sealed properly.

 

On Johnson's parts list there is a wear plate available for this pump which appears to be held in place by a pin but I cannot see a pin in the chamber.

 

Has anybody used one of these wear plates?

 

The back of the chamber has ridges in it and no wear where the cam is, would I have to have the back of the chamber machined level so the wear plate is level?

Many years ago I had a problem like this with a Jabsco pump which was obsolete (although impellors were available), after a lot of messing I managed to solder up the grooves in the back plate and smooth it off, but still had problems getting a good seal, due to thickness of the gasket, which seemed to be crucial.

A lot of these types of pump have a groove for the vanes of the impellor to follow, but any debris which goes through the pump often wears aways both plates to a stage were a seal can be difficult. I was lucky in that the front wear plate was reversible, but it can be difficult to get the distance right so that the pump works but does not put to much pressure on the impellor!

 

One possibility is that if you can have the casing machined, you may be able to mill the front edge to maintain the right distance, but original dimensions would be essential!

There are substitute pumps available, but if it is one that has a key drive rather than a pulley, getting the right fitting will be a problem?

[davel]

Thanks Robin

 

I have found that there are a couple of replacement pumps available and I would be happier with a new pump as we are doing the Ribble link in a couple of weeks time.

 

Dave

[Tony Brooks]

The raw water pump on Iona started dripping a while ago. I took the pump apart and found that the seals had worn a groove in the shaft. After finding that the pump and shaft are obsolete I replaced the seals knowing it would only be a temporary fix and on our recent visit to Kent I took the pump off and had a local engineering firm turn down the part of the shaft where the seals sit from 16mm dia to 15mm dia to remove the groove (after checking that I could get 15mm ID seals).

 

When I stripped down the pump two of the impeller vanes were damaged but I figured some debris had got into the pump at some point.

 

On our return to the boat I replaced the pump and fired up the engine and took the dog for a walk only to notice on my return that there was no water coming out with the exhaust.

 

I stripped the pump again to find that all the vanes on the impeller were completely destroyed.

 

I put my last spare impeller on and tried again this time watching to make sure that the pump was pumping, but still no water with the exhaust.

 

I stripped the pump again and realised that there is a lot of wear at the back of the pump chamber and a small amount of wear to the faceplate.

 

It appears to me that there is now a gap at each end of the impeller and water can get around the impeller my feeling is that this is the problem but my neighbour were we are moored reckons that I should use gasket goo to make sure the faceplate is sealed properly.

 

On Johnson's parts list there is a wear plate available for this pump which appears to be held in place by a pin but I cannot see a pin in the chamber.

 

Has anybody used one of these wear plates?

 

The back of the chamber has ridges in it and no wear where the cam is, would I have to have the back of the chamber machined level so the wear plate is level?

 

Any advice?

 

 

On my Johnson pump the wear plate is held in place by the cam. Undo the cam retaining screw and remove the cam. Bang the pump down hard onto a piece of soft wood so the face is not damaged but the plate can be shocked out. I would put a smear of jointing compound on the scored face (to become the back) of the cam before fitting, also on the back of the cam.

 

Have you retrieved the broken vanes from the system? They can cause blockages, often in an elbow.

 

Anything that raises the back pressure in the exhaust can stop these pumps working such as delaminating exhaust hose or a scaled up mixing elbow (or a winterisation rag still in the exhaust pipe!)

[Tony Brooks]

PS

 

The bit about the new impeller being destroyed. This will happen if there is no water moving through a running pump. Have you got a bread wrapper or some such hooked up on the water intake?

[davel]

Thanks Tony

 

I was looking at the diagram on the Johnson website and saw the wear plate, but after speaking to the guy at Aquafax the model I have does not have one.

 

I gathered all the remains together and there are no large pieces missing, but I'll see if I can check that water flows through tomorrow.

 

The inlet does not appear to be blocked, I started opening the sea cock with the pump off and water flowed in freely enough.

 

I am convinced now that there is a too much wear on the end faces for the pump to work and am steeling myself to buying a new pump tomorrow.

 

Cheers for the advice

 

Dave

[Tony Brooks]

Thanks Tony

 

I was looking at the diagram on the Johnson website and saw the wear plate, but after speaking to the guy at Aquafax the model I have does not have one.

 

I gathered all the remains together and there are no large pieces missing, but I'll see if I can check that water flows through tomorrow.

 

The inlet does not appear to be blocked, I started opening the sea cock with the pump off and water flowed in freely enough.

 

I am convinced now that there is a too much wear on the end faces for the pump to work and am steeling myself to buying a new pump tomorrow.

 

Cheers for the advice

 

Dave

 

 

Having checked the sheets from several sources and knowing that both Jabsco & Johnson plumps use wear plates in all but the smaller sizes I think you should do as I suggest and take the cam out. I bet there is a wear plate in there. Both it and the cover can be reversed to give more service.

 

Some of these pumps seal the face plate with an O ring and some with a gasket. If it is a gasket one then did you fit the gasket correctly so it matches the cam? Did you make a gasket because if so I bet you made it from over thick material.

 

PS check Cleghorn Wearing (the pump shop) in case a Jabsco is cheaper. They tend to be fairly interchangeable.

Edited April 7, 2011 by Tony Brooks

[jake_crew]

Please advise what your new pump is, pref with some pictures and the spec.

[Ange]

I ordered the Johnson pump that replaced the obsolete one but that has become obsolete fairly recently as it was still in the Aquafax catalogue, so am now looking at a Jabsco alternative which so far appears to be almost twice the price.

 

The Johnson was part no 10-24451-01

 

Jabsco is 23430-1201

 

I could not find any images for either.

 

Why did you want to know?

 

Having checked the sheets from several sources and knowing that both Jabsco & Johnson plumps use wear plates in all but the smaller sizes I think you should do as I suggest and take the cam out. I bet there is a wear plate in there. Both it and the cover can be reversed to give more service.

 

Some of these pumps seal the face plate with an O ring and some with a gasket. If it is a gasket one then did you fit the gasket correctly so it matches the cam? Did you make a gasket because if so I bet you made it from over thick material.

 

PS check Cleghorn Wearing (the pump shop) in case a Jabsco is cheaper. They tend to be fairly interchangeable.

 

I have taken the cam out and had a close visual inspection. I guess with the amount of wear it has suffered the join between plate and chamber might be well hidden but I will try whacking it to see if a wear plate comes out.

 

But - if it does it has worn a fair bit except wear the cam is, it would need some careful filing to even it up so it sits square when replaced in reverse.

 

It is a gasket and I used a new one that came with the service kit I bought with the spare impeller.

 

ETA damned imposter (That was Dave forgetting to sign in as himself btw)

Edited April 7, 2011 by Ange

[Tony Brooks]

I ordered the Johnson pump that replaced the obsolete one but that has become obsolete fairly recently as it was still in the Aquafax catalogue, so am now looking at a Jabsco alternative which so far appears to be almost twice the price.

 

The Johnson was part no 10-24451-01

 

Jabsco is 23430-1201

 

I could not find any images for either.

 

Why did you want to know?

 

 

 

I have taken the cam out and had a close visual inspection. I guess with the amount of wear it has suffered the join between plate and chamber might be well hidden but I will try whacking it to see if a wear plate comes out.

 

But - if it does it has worn a fair bit except wear the cam is, it would need some careful filing to even it up so it sits square when replaced in reverse.

 

It is a gasket and I used a new one that came with the service kit I bought with the spare impeller.

 

ETA damned imposter (That was Dave forgetting to sign in as himself btw)

 

 

So its not the gasket.

 

The new part number you quoted also shows a wear plate. Once the cam is out you should be able to see the end of the locating pin.

 

If the plate does come out please do not file anything. That will be making the plate thinner. Simply put some jointing (silicon) on the original outside face, turn it over and insert it so the jointing is against the body.

 

Likewise note the numbers on the cover, give the number side a quick rub over with wet & dry to remove any burs/paint and fit it in reverse with the numbers now on the inside.

 

Given half a chance any of these pumps will suck air down the shaft, especially with a high raw water lift, so it may all be down to the 15mm seal unless its OD is the same as the old one.

Edited April 7, 2011 by Tony Brooks

[RichardH]

I sympathise. We have taken the step of changing our raw water cooled boat to keel cooled as the parts for the pump were becoming like hens teeth.

[RobinJ]

I ordered the Johnson pump that replaced the obsolete one but that has become obsolete fairly recently as it was still in the Aquafax catalogue, so am now looking at a Jabsco alternative which so far appears to be almost twice the price.

 

The Johnson was part no 10-24451-01

 

Jabsco is 23430-1201

Johnson

Jabsco (only listed!)

[jake_crew]

The reason for asking about available water pumps is that we'll need one next year when the repaired Gleniffer is dropped back into Pintail.

 

So a source of external, shaft drive water pumps is useful to know.

[Ange]

The reason for asking about available water pumps is that we'll need one next year when the repaired Gleniffer is dropped back into Pintail.

 

So a source of external, shaft drive water pumps is useful to know.

 

No probs

 

I ended up getting the Jabsco from ASAP Supplies and although it was not in stock they have said it will be with me by Friday. A quick Google did not turn up the spec but it must be on t'interwebthingy somewhere or ask Jabsco to send the info.

 

I'll send a piccie of the pump when it arrives.

 

Cheers

 

Dave

 

posting as Ange

[soldthehouse]

No probs

 

I ended up getting the Jabsco from ASAP Supplies and although it was not in stock they have said it will be with me by Friday. A quick Google did not turn up the spec but it must be on t'interwebthingy somewhere or ask Jabsco to send the info.

 

I'll send a piccie of the pump when it arrives.

 

Cheers

 

Dave

 

posting as Ange

I hope you arent on the maltesers and pink stuff too Dave!

[davel]

I hope you arent on the maltesers and pink stuff too Dave!

 

 

No it was the Goat Shed Cider.