MD2020 saltwater pump

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Neeves

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I have a persistent weep of oil from the 'gear' end of the saltwater pump. I have replaced both mechanical seals (the seawater/impeller end and the seal for the oil end), but the leak persists. Its not a major leak - just messy and annoying - as it needs a contortionist with plenty of time and with very small but strong fingers to disassemble and then reassemble

I assume there may be wear, so the new seal is ineffective.

Does this mean a new shaft or a complete new pump housing? How does one determine (if it might be one or other) where the leak might be.

Thanks
 
I would suspect the shaft has a worn ring on it where the seal is. Despite a new seal this allows oil to weep past the seal. If you look at the shaft, you'll find a bright band on the shaft which, if you run you finger nail across it, is slightly indented. I think you'll find you can get a rebuild kit for the pump which includes a new shaft. Remove the pump, disassemble it and rebuild using the new seals and shaft in the kit.
 
That was quick!

The shaft kit is certainly cheaper than the pump - the latter is extortionate (my eyes are watering)

I'll disassemble, again, and try the sensitive finger rub test.

The installation of the pump must have been an afterthought - its such a simple attachment and, almost, impossible to remove. But must keep Volvo service agent's pension schemes well topped up.

Very many thanks.

Jonathan
 
TSB240 said:
Shaft Kit

http://www.keypart.com/stock/21951416

A bit cheaper than a pump!

http://www.keypart.com/stock/3593654
Click to expand...

I have the same problem and intend to tackle it this winter.
Is the kit you show enough, will I not need http://www.keypart.com/stock/21951370
as well. Do you know if this is giving the same as the refurb kit offered by volvo agents for over £200?
When I last dealt with this same problem a few years ago I had the agents fit the kit as Idon't know if I can do the dis/assembly. I only therefore saw the pump and kit in assembled form as I gave it to them and collected.
 
johnphilip said:
I have the same problem and intend to tackle it this winter.
Is the kit you show enough, will I not need http://www.keypart.com/stock/21951370
as well. Do you know if this is giving the same as the refurb kit offered by volvo agents for over £200?
When I last dealt with this same problem a few years ago I had the agents fit the kit as Idon't know if I can do the dis/assembly. I only therefore saw the pump and kit in assembled form as I gave it to them and collected.
Click to expand...

Did mine last year.

No you shouldn't need all the additional kit just the easily damaged thin cover plate gasket.

In my case I needed to borrow a three legged puller to pull the drive gear off the in board end of the shaft.
Otherwise it is just a simple job with basic tools to remove pump, shaft seals and bearings. Just make sure you put everything back the way you found them!
 
Neeves said:
That was quick!

The shaft kit is certainly cheaper than the pump - the latter is extortionate (my eyes are watering)

I'll disassemble, again, and try the sensitive finger rub test.

The installation of the pump must have been an afterthought - its such a simple attachment and, almost, impossible to remove. But must keep Volvo service agent's pension schemes well topped up.

Very many thanks.

Jonathan
Click to expand...

Buying a pump direct from Jabsco is cheaper than VP...https://www.jabscoshop.com/jabscoshop-spare-parts/29350-1101-pump-19mm-brz-10-flange.htm
 
I do wonder why you cannot buy the shaft, alone, without the bearings and spacer.

Why the oil seal should develop a leak - do not know. It is only nuisance value unless you are motoring for hours.

I would say I'm replacing seals every 750 hours, and I do both at once (the seals are not expensive) and my engine has 2,300 hours, and the shaft is apparently worn.

I found there was insufficient room to turn the bolts because the engine supports get in the way of the spanner or socket. I could 'break' the bolts but they were then too stiff to turn with fingers (I am a wimp). I simply cut a cheap spanner down so that the handle was 20mm long, that worked. A gear puller helps but you can simply tap the shaft with a wooden or rubber hammer whit the gear supported on more wood, it should not do any harm.

Its a very simple disassembly and re-assembly - just so difficult with those hard to get at bolts, I think 2 bolts have nuts the other 2 are tapped into the engine casting (but do not recall exactly).. You need to remove the impeller to start with as the shaft comes out the opposite side to the impeller.

But the pumps are standard Jabsco units, so I assume the shaft is from Jabsco - so why not simply a spare shaft?

Jonathan
 
I suspect the reason for selling shafts as a kit with seals is that if you change only the shaft, you'd have to re-use the seals. And the thinking is probably that old shaft = old seals, so they need changing too.
 
Neeves said:
I found there was insufficient room to turn the bolts because the engine supports get in the way of the spanner or socket. I could 'break' the bolts but they were then too stiff to turn with fingers (I am a wimp). I simply cut a cheap spanner down so that the handle was 20mm long, that worked. A gear puller helps but you can simply tap the shaft with a wooden or rubber hammer whit the gear supported on more wood, it should not do any harm.
Jonathan
Click to expand...
Yes access to the pump securing bolts is another triumph of Volvo serviceability. Actually I found that a timber wedge under the sump to support the engine and now remove the offending engine mount was an easier than expected solution. I do have a saildrive so that disturbing the engine alignment was not an issue.
Thanks for the tip on needing a puller.
 
MM5AHO said:
I suspect the reason for selling shafts as a kit with seals is that if you change only the shaft, you'd have to re-use the seals. And the thinking is probably that old shaft = old seals, so they need changing too.
Click to expand...

Its not the new seals - its the new bearings! Seals are cheap, I suspect the bearings are quite pricey.
 
johnphilip said:
Yes access to the pump securing bolts is another triumph of Volvo serviceability. Actually I found that a timber wedge under the sump to support the engine and now remove the offending engine mount was an easier than expected solution. I do have a saildrive so that disturbing the engine alignment was not an issue.
Thanks for the tip on needing a puller.
Click to expand...

Thanks for the tip on the wooden wedge.
 
Neeves said:
I do wonder why you cannot buy the shaft,
so why not simply a spare shaft?

Jonathan
Click to expand...
Yours is leaking oil which is ok as bearings are probably still good. Most seem to fail by leaking sea water so by that time both bearings have been running in sea water with high amounts of suspended solids . Hence the kit includes bearings !
 
TSB240 said:
Yours is leaking oil which is ok as bearings are probably still good. Most seem to fail by leaking sea water so by that time both bearings have been running in sea water with high amounts of suspended solids . Hence the kit includes bearings !
Click to expand...

I'm not convinced.

If the sea water seal leaks water it runs into the bilges and cannot get into the sealed engine section unless it 'gets through' the oil seal (in which case there will be oil leaking from the 'engine' seal. There is also a gap between the seawater and oil side, its visible - in my case with a 'miniscus'? film of oil on the shaft. The engine section houses the bearings - so unless both seals fail then there should be no seawater in the oil.

I know pictures would be nice - who would guess what to take pictures of in advance!

But I'm certainly no mechanic!

I'm searching to see if sourcing just the shaft is possible, though not optimistic.

Jonathan
 
The cause of permanent leaks, even with a new seal, is that a groove has been worn in the shaft, increasing the clearance between it and the seal lip. A way of improving the situation is simply to not press the seal fully home, allowing the lips to sit on a new part of the shaft. A simple shim made up of thin plastic or even cardboard, placed into the housing before the seal is pressed home, will hold the seal in the new position.
 
vyv_cox said:
The cause of permanent leaks, even with a new seal, is that a groove has been worn in the shaft, increasing the clearance between it and the seal lip. A way of improving the situation is simply to not press the seal fully home, allowing the lips to sit on a new part of the shaft. A simple shim made up of thin plastic or even cardboard, placed into the housing before the seal is pressed home, will hold the seal in the new position.
Click to expand...

An alternative which I discovered accidentally when changing windlass oil seals and oil seals on a car drive shaft recently is to look at the seal size and buy a slightly different size.

For example, the OEM seal will be something like 20:30:7 so go online and buy a 20:30:6 or, if you have the clearance, a 20:30:8. Both of these will press fully home and seal on an unworn point on the shaft and will be so cheap you could buy both and try the larger one first to check the clearance.

Vyv's method of not pressing fully home will work but might well leave you with a slightly off-line seal which will wear quickly and also be prone to leak-past.

Richard
 
Thanks Vyv and RichardS. Your solutions sound much cheaper than a new shaft!

edit -What are these things called, technically. I call them mechanical seals, as that's what I think monster ones are called for hydro-electric power stations! close edit

I have a new genuine Volvo seal on the boat. I do not recall how the box, or seal, are marked - if at all. Though I know there is a Volvo part number on the box. How does one determine seal size? to resolve the numerical designation you quote (or what do the numbers mean?). I'm assuming one is an OD, one is an ID what's the other, width? I can obviously measure with a micrometer.

Other than Volvo dealers - who sells this sort of thing, car part retailers? anyone else (these seals seem quite small for a car).

Sorry to be so ignorant :)

Jonathan
 
Last edited:
Neeves said:
Thanks Vyv and RichardS. Your solutions sound much cheaper than a new shaft!

edit -What are these things called, technically. I call them mechanical seals, as that's what I think monster ones are called for hydro-electric power stations! close edit

I have a new genuine Volvo seal on the boat. I do not recall how the box, or seal, are marked - if at all. Though I know there is a Volvo part number on the box. How does one determine seal size? to resolve the numerical designation you quote (or what do the numbers mean?). I'm assuming one is an OD, one is an ID what's the other, width? I can obviously measure with a micrometer.

Other than Volvo dealers - who sells this sort of thing, car part retailers? anyone else (these seals seem quite small for a car).

Sorry to be so ignorant :)

Jonathan
Click to expand...

I've always called them oil seals and if you type that into eBay you find thousands of them. However, I've recently bought new seals for the prop end of my saildrive shaft and these are actually water seals I guess. However "oil seal with a stainless spring" still seems to do the trick! Perhaps "shaft seals" would be a better generic term?

The sizes are in mm and are indeed ID:OD:Thickness as you say. Often stamped on the seal face in tiny numbers. Or can be measured from the seal housing as you say or you might find in online.

Good luck

Richard
 
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