What causes a Jabsco cooling water to leak like this?

Otter

Otter

Well-Known Member
Joined
23 Nov 2004
Messages
10,931
Location
Norfolk
Visit site
The Jabsco raw water pump has never given trouble but today on recommissioning after a couple of months ashore we ran up the engine and afterwards it dripped from underneath the middle part of the pump. We took off the speed seal and cleaned and reseated it just to check. It still dripped about 100 drips a minute. I then started up the engine and ran it, the pump stopped dripping and didn't drip again. The engine is a Thornycroft 235 but it's a standard off the shelf Jabsco though likely 38 years old.

That's fine for now but is there something wrong? A dodgy pump in the middle of the North Sea will be no joke so what's the likely cause and the best solution?

Thanks.
 
Colvic Watson said:
The Jabsco raw water pump has never given trouble but today on recommissioning after a couple of months ashore we ran up the engine and afterwards it dripped from underneath the middle part of the pump. We took off the speed seal and cleaned and reseated it just to check. It still dripped about 100 drips a minute. I then started up the engine and ran it, the pump stopped dripping and didn't drip again. The engine is a Thornycroft 235 but it's a standard off the shelf Jabsco though likely 38 years old.

That's fine for now but is there something wrong? A dodgy pump in the middle of the North Sea will be no joke so what's the likely cause and the best solution?

Thanks.
Click to expand...

Difficult to say exactly why leak should start and stop, don't think its anything to do with the speed seal plate, but slight float on the pump shaft can cause this. However I would say that your internal pump shaft seal is showing signs of failure and that it and maybe the pump shaft and its bearings require replacing. Alternatively the fastest fix would be a new pump.
 
I wondered because it's not a job I can do - engineering is just something I can not do. So by the time they've take it off, taken it apart and refitted it........what is the cost of a 'typical' Jabsco water pump?
 
Colvic Watson said:
The Jabsco raw water pump has never given trouble but today on recommissioning after a couple of months ashore we ran up the engine and afterwards it dripped from underneath the middle part of the pump. We took off the speed seal and cleaned and reseated it just to check. It still dripped about 100 drips a minute. I then started up the engine and ran it, the pump stopped dripping and didn't drip again. The engine is a Thornycroft 235 but it's a standard off the shelf Jabsco though likely 38 years old.

That's fine for now but is there something wrong? A dodgy pump in the middle of the North Sea will be no joke so what's the likely cause and the best solution?

Thanks.
Click to expand...

It means that the seal at the back of the pump cavity is cream crackered.

Water passing the seal is coming out of a drain hole, there for the purpose.

If this is a pump directly driven by the engine, as opposed to being belt driven, there will also be an oil seal. While the water leak is not too bad water will simply escape from the drain hole but if ( when!) it gets worse water may well be forced past the oil seal into the engine crankcase.

If a belt driven pump the water will get into the bearings probably.

Now is the time to overhaul the pump. New seals, inspect bearings check shaft for wear. Look at overall wear of the pump esp end plates and the cam plate if its a flexible vane pump
 
Last edited:
Sounds like a build up of crevice corrosion on the seal face during the lay up period and the running has lapped the seal faces back in.

Is it a Jabsco of Johnson ? They are very similar.

Keep an eye on it and if it is still OK after several hours running it will likely be OK, but worthwhile checking the impeller hasn't started developing any cracks.

Changing the seals and bearings isn't too difficult for any engineering workshop and a lot cheaper than a new pump.

I have a detailed technical manual covering most Johnson Pumps - PM me if you would like a copy.
 
Thank you that's very kind. It's definitely a Jabsco (stamped) and a flexible vane impeller. Sounds like a complete overhaul :(
 
Colvic Watson said:
I wondered because it's not a job I can do - engineering is just something I can not do. So by the time they've take it off, taken it apart and refitted it........what is the cost of a 'typical' Jabsco water pump?
Click to expand...

Should be easy enough job to get off - 2/3 nuts to undo 2 pipes to take off and wiggle pump out. Pop it in to marine engineers to fix if you don't feel confident - refit. Failing that Jabscos retail between £150 - coupla' grand depending on model - look on website and match up. ASAP also do them but new website is crap. Also consider Johnson pumps - they seem to match some Jabscos and are cheaper.
 
Colvic Watson said:
I wondered because it's not a job I can do - engineering is just something I can not do. So by the time they've take it off, taken it apart and refitted it........what is the cost of a 'typical' Jabsco water pump?
Click to expand...

Probably less than an hours work to take the pump off, replace seals (and bearings/shaft if needed) and refit pump. Even paying an engineer, a lot cheaper than replacing the pump.
 
Looked into price of parts recently - shaft £90, rubber seals £40 engineers time say £40 impellor say £20 - might make sense to buy new if it's 38 years old and one of the smaller pumps.
 
ripvan1 said:
Looked into price of parts recently - shaft £90, rubber seals £40 engineers time say £40 impellor say £20 - might make sense to buy new if it's 38 years old and one of the smaller pumps.
Click to expand...

Prices vary significantly. A kit for the pump on my VP 2003 containing seals, bearings and shaft is around £50. A new pump is around £270.
 
OK, sounds like at least I can get it off. I'll hand it to the engineers and ask for the two quotes. I remember an article in PBO about how a very slightly worn cam disproportionately affects the water flow. It's irritating having to do this but better than discovering the problem half way along the Frisians.
 
I replaced my crankshaft mounted Jabsco due to sheared off cover screws and one or two other bits, as it was less than the cost of parts and I could do the whole lot myself, about £250 IIRC two years back or so
 
Colvic Watson said:
I wondered because it's not a job I can do - engineering is just something I can not do. So by the time they've take it off, taken it apart and refitted it........what is the cost of a 'typical' Jabsco water pump?
Click to expand...

If your not an engineer then don't even think of rebuilding it, just get a replacement. The replacement will take 20 minutes to instal. You will need some circlip pliers.
 
Chris_Robb said:
If your not an engineer then don't even think of rebuilding it, just get a replacement. The replacement will take 20 minutes to instal. You will need some circlip pliers.
Click to expand...

I agree this this if you feel unable to repair it your self. You could then get an "Engineer" to repair the existing one and keep it on-board as a spare.
 
Rogershaw said:
I agree this this if you feel unable to repair it your self. You could then get an "Engineer" to repair the existing one and keep it on-board as a spare.
Click to expand...

That's what I have done. Mine let fly with no dripping to pre warn me off a nasty coast with a rising gale. I had a new one, but was frighten of fitting it there. We continued on with constant pumping of the engine compartment (luckily a separate bilge) as the engine was still cooling just. When we got into Pythagoras, we replaced the pump - borrowing a set of circlip pliers from the nextdoor brit. Took us 20 minutes start to finish. The old one now sits as a spare.

The fault turned out to be the back plate behind the impeller, which is normally located with a stud - which had gone - warn flat? the plate was spinning with the impeller and somehow destroyed the shaft O ring.
 
Thank you for those. I'm having trouble identifying the pump - I can't see a part number printed anywhere on it. It's on a Thornycroft 230. Here's a picture. Any help identifying it is a gratefully received:

View attachment 55681

I need to clean my engine though - look at the dust!
 
Cleghorn Waring are distributors look up their website
Full details there
The pump details will be on the original jabso cover if you still have it
 
You must log in or register to reply here.

Share this page

Top