Lister JPM water pump - advice on leak wanted

[starman]

I've just been out for a short test run and on return noticed that coolant is dripping from the bottom of the water pump into the engine bilge - it's one of the traditional piston type pumps.

It's virtually impossible to see where the leak actually is but it seems to be where the pump joins the body of the engine.

I don't want to start pulling things apart without knowing what I'm doing and I can find nothing about this pump in my JPM manual which only seems to talk about gear or belt driven pumps that look quite different.

I can live with the leak if needs be but could it be fixed, and for that matter what sort of routine maintenance do these pumps need?

Thanks in advance for any info.

[steamraiser2]

Water leaks are common with this type of pump. Even Lister gave up in the end which is why later engines have Jabsco type pumps ( JS models for example). If you log on to the Marine Power Services website you will find the maintenance information you need for free.

 

Not our favourite water pumps, we have a pile of them dumped in our store alongside the heap of Blackstone gearboxes!

[starman]

Water leaks are common with this type of pump. Even Lister gave up in the end which is why later engines have Jabsco type pumps ( JS models for example). If you log on to the Marine Power Services website you will find the maintenance information you need for free.

 

Not our favourite water pumps, we have a pile of them dumped in our store alongside the heap of Blackstone gearboxes!

Yes, but they do look impressive! Not so sure I'll grow to love the Blackstone though but a hydraulic conversion is beyond my pocket sadly!

[martyn 1]

They do look impressive! I love the big lump of brass but I hate water in the bilges more (messy) so its not the pump of my choice.

 

But that isn't much help to you as that is what you have, so depending on how much water is leaking you may be able to reduce it as much as you can. firstly a new set of seals would help but you would also need to very closely check the pump bore for wear. Any scores or excessive ovality and it will not seal in a month of Sundays!!!. the wear is usually cured by over boring the pump body, fitting it with a sleeve and returning it to original dimensions.

 

Yes, but they do look impressive! Not so sure I'll grow to love the Blackstone though but a hydraulic conversion is beyond my pocket sadly!

[starman]

They do look impressive! I love the big lump of brass but I hate water in the bilges more (messy) so its not the pump of my choice.

 

But that isn't much help to you as that is what you have, so depending on how much water is leaking you may be able to reduce it as much as you can. firstly a new set of seals would help but you would also need to very closely check the pump bore for wear. Any scores or excessive ovality and it will not seal in a month of Sundays!!!. the wear is usually cured by over boring the pump body, fitting it with a sleeve and returning it to original dimensions.

Thanks for the advice. What I can't find anywhere though is any info on how to dismantle or service the pump - my manual doesn't cover it and nor, I think, does the one on your website. Presumably it uses some sort of standard water pump grease?

[monkeyhanger]

Thanks for the advice. What I can't find anywhere though is any info on how to dismantle or service the pump - my manual doesn't cover it and nor, I think, does the one on your website. Presumably it uses some sort of standard water pump grease?

I seem to remember recommending some time ago on this forum that you change the leather washers on the reciprocating piston. Did you do that? If not, it's very easy.

You need to drain the system and disconnect the water pipes from the pump first. Then you take the cover of the front of the con rod-3 small bolts. Inside you will find a lot of grease and buried in there is a circlip which retains the bearing on the central shaft. After removing it you should find that the bearing will slide forward towards you. It may need a bit of help with a screwdriver behind the housing, but proper engineers may use a small puller. It won't be tight, well, mine wasn't. Once that's loose, you can remove the four half inch mounting nuts (on studs) and withdraw the whole pump, including the piston and conrod towards you.

You can now slide the piston out of the bore and you have easy access to the washers. They're dead easy to change and refitting the pump is the opposite of removal.

I would recommend that you check the piston bore for wear-I used a small steel rule inside the bore to check if the walls were straight. You could use an internal micrometer to check the internal diameter, but, as it's unlikely to be worn right at the top or right at the bottom, as (hopefully) nothing should make contact, the straight edge may probably do the trick..

While the pump body is off the engine, it's worthwhile taking time to clean up the main casting. It's phosphor bronze and it responds well to a rotary wire brush in an an electric drill.

If you're going this far you may as well consider replacing the bearing while you're at it. Well worth it for a few quid.

I bought my leather washers from Tony Redshaw. If you're going to see him, I'd suggest taking the pump to get him to check for wear. If it is badly worn it can be rebored and sleeved.

Before putting in the washers, I'd suggest you soak them. I did mine in water but I've heard some people recommend oil.

If it's a straight "change the washers" job it shouldn't take more than one and a half hours. It's not difficult at all.

My water pump is now totally watertight ( he says smugly) Good Luck! Jack

Edited May 19, 2013 by monkeyhanger

[starman]

I seem to remember recommending some time ago on this forum that you change the leather washers on the reciprocating piston. Did you do that? If not, it's very easy.

You need to drain the system and disconnect the water pipes from the pump first. Then you take the cover of the front of the con rod-3 small bolts. Inside you will find a lot of grease and buried in there is a circlip which retains the bearing on the central shaft. After removing it you should find that the bearing will slide forward towards you. It may need a bit of help with a screwdriver behind the housing, but proper engineers may use a small puller. It won't be tight, well, mine wasn't. Once that's loose, you can remove the four half inch mounting nuts (on studs) and withdraw the whole pump, including the piston and conrod towards you.

You can now slide the piston out of the bore and you have easy access to the washers. They're dead easy to change and refitting the pump is the opposite of removal.

I would recommend that you check the piston bore for wear-I used a small steel rule inside the bore to check if the walls were straight. You could use an internal micrometer to check the internal diameter, but, as it's unlikely to be worn right at the top or right at the bottom, as (hopefully) nothing should make contact, the straight edge may probably do the trick..

While the pump body is off the engine, it's worthwhile taking time to clean up the main casting. It's phosphor bronze and it responds well to a rotary wire brush in an an electric drill.

If you're going this far you may as well consider replacing the bearing while you're at it. Well worth it for a few quid.

I bought my leather washers from Tony Redshaw. If you're going to see him, I'd suggest taking the pump to get him to check for wear. If it is badly worn it can be rebored and sleeved.

Before putting in the washers, I'd suggest you soak them. I did mine in water but I've heard some people recommend oil.

If it's a straight "change the washers" job it shouldn't take more than one and a half hours. It's not difficult at all.

My water pump is now totally watertight ( he says smugly) Good Luck! Jack

Brilliant - just the info I needed - thanks. Any particular sort of grease BTW?

[monkeyhanger]

Brilliant - just the info I needed - thanks. Any particular sort of grease BTW?

I use Morris's water resistant grease. I also use it in the prop shaft greaser. It seems very good

[George94]

Water leaks are common with this type of pump. Even Lister gave up in the end which is why later engines have Jabsco type pumps ( JS models for example). If you log on to the Marine Power Services website you will find the maintenance information you need for free.

 

Not our favourite water pumps, we have a pile of them dumped in our store alongside the heap of Blackstone gearboxes!

 

Oi! What's wrong with a Blackstone gearbox?

[martyn 1]

Nothing while in perfectly good working order

 

But a pain in the bum to recondition. finding new parts is hard work to impossible depending what your after. hence you need a heap of them when you rebuild alot

Oi! What's wrong with a Blackstone gearbox?

[George94]

Nothing while in perfectly good working order

 

But a pain in the bum to recondition. finding new parts is hard work to impossible depending what your after. hence you need a heap of them when you rebuild alot

 

Yes, I can imagine that. Do the clutch plates tend to go on forever if not abused, or should I expect mine to give up at some point?

 

In which case, I shall probably wander down to Poole.