Raw water pump seals

[Ruffles]

I was reading this excellent article on refurbishing raw water pumps on the train this morning. I have my leaking spare pump in the garage and want to buy some new seals and bearings. However in the article it shows the water seal as distinctly different from the oil seal.

Now my pump here is the Volvo Penta variant (££) of the same Johnson pump. I've removed both the seals and they were both oil type. Also, when I look at the VP parts diagram here it shows the same component specified for both. Ignore the prices - I will NOT be buying from them!

So should I try to source a water rather than oil seal? If so, where do you get them?

Also, I need to replace the bearings as well. I can buy stainless for a tenner versus 2 quid for steel. Do you reckon it's worth the extra?

Thanks,

PS: Hope the Picasa web link works. Can't remember if I've published the folder.

 

[Refueler]

All seals and bearings can be bought as pattern items. All you need is the ID number - which is like the ISBN number of a book. Bearings usually have it stamped into the inner ring around the face edge.

There is no need to buy a pricey "manufacturers" version that is most likely same pattern one rebranded.

With seals on my Jabsco raw water pump - I just took the old into the local shop and he matched it with pattern one. Luvly job. No more drips or leaks.

 

[VicS]

Important points about the seals will be that the oil seal is in fact resistant to oil and that the spring in the water seal is stainless so that it does not rust. No reason why the same seal should not satisfy both criteria. Sensible if they are the same (if they are the same size) as then interchangeable.

Note the correct orientation of the seals ... back to back.

The spacer between has been discontinued in (some, maybe all) Volvo pumps and the manuals even advise removing existing spacers.

Don't just replace one, silly to rebuild with one old seal still in use.

Inspect bearings very critically and replace if necessary or if in doubt. Cannot see any particular reason to use stainless bearings ... your call.

inspect shaft for wear ridges. Some times it is possible to reposition seals to run on an unworn part of the shaft but probably not with these pumps.

Ensure seals are fitted squarely if not up against a shoulder.

Consult workshop manual regarding sealant between seal and housing. Not normally required but is sometimes.

bearings and seals should hopefully be available at a fraction of Volvo prices from your local bearing stockist if not OEM parts.

Beware of delivery charges if they have to get them in specially (I bought a small seal for my Pressure washer from a bearing stockist, had to be delivered from their central store and cost me about 10 times as much for the delivery as the cost of the seal)

 

[Ruffles]

Yes I know. But the point is that VP appear to be flogging them with oil seals instead of water seals. Which is probably why they are such a regular subject on this formum - they fail prematurely! Hardly surprising if the seal is designed for oil and encounters gritty salt water.

The article refers to a pump for a Westerbeke engine but the pump is Johnson. The water seal in the photo looks the same size as the oil seal next to it but is a completely different design.

 

[VicS]

It'd be interesting to know what the differences are between seals designed specially for water or specially for oil.

Salt in the water wont be of any importance but if you are running gritty water through your pump I expect you'll be replacing impellers very frequently and pump bodies too.

 

[Ruffles]

It'd be interesting to know what the differences are between seals designed specially for water or specially for oil.

Salt in the water wont be of any importance but if you are running gritty water through your pump I expect you'll be replacing impellers very frequently and pump bodies too.

It occasionally pumps pure mud. Ran aground at the beginning of the season on a falling tide and used a lot of reverse getting off. The impeller failed that weekend. The first time in ten years of having the boat. Could be a coincidence but... The filter is the old fashioned bronze tube which removes weed but not much else. The pump body is not worn at all though.

One of the mechanics at the VP dealer at Haslar last month showed me a pump that had been eaten by electrolysis. There was a 5mm gap at the back of the impeller. Really odd.

 

[TonyS]

Material differences of seals

The main choice of material for a seal is the temperature range. Most general purpose seals are compounded from nitrile rubber which has an adequate temperature range for most application up to 100C. Above this temperature silicone rubber or viton are used and sometimes for special applications the seal can have a PTFE lip. Nitrile seals with be equally good for water or oil. I have just replaced my water seal on a VP 2030D in situ using the techniques described on these forums. My seal had done 1050 hrs and was considered to be exceptionally high by VP agent. The seal from a VP agent cost £4 and the old and new were Gaco DPSM 12247. It is a simple 20min job. In my humble opinion the cause of the failure of the seal is the same as for the impellers on these pumps and that is the pump often runs dry. The water is sucked out of the pump through the air vent when sailing fast or after a lift out etc. The simple remedy I think, is to fit a non return valve to prevent it happening.

 

[Ruffles]

A quick follow up 'cos I've just refurbished the pump.

Here's the original water side seal.

This appears to be original since it has some green paint on it. Not too impressive is it.

I've replaced it on the salt water side with one of these.

This is a Viton oil seal and is resistant to salt water. I've chosen the double lip seal to move the wear point on the shaft though there appears to be little wear. It's a whole £2.50 more expensive so quite an investment. I've used a standard seal on the oil side.

Also I've just proved to myself that it doesn't matter which way you bend the vanes when you insert the impeller. With the pump off the engine I could turn the shaft by hand and the vanes re-orientate when you reverse.

 

[VicS]

Viton is Duponts registered name for what I think you'll find described as a "fluoroelastomer". That and nitrile rubber have "very good" resistance to oil and "good" resistance to water. Teflon (PTFE) has the best resistance of all to water.

The trouble is that no elastomeric material is ideal for use with water because it is a relatively poor lubricant.

The vitally important thing about the water seal is that it has stainless steel garter spring.

Pleased to hear that someone has proved that it does not matter which way the vanes are prefolded on the pump impeller. Can now answer all questions about it by saying it does not matter and do so with confidence.

 

[Ruffles]

Actually, looking closely at the failed seal, the garter appears to be ok. It's the mild steel stiffening ring in the seal body that has failed. So the leak was between the seal and the pump body.

 

[Refueler]

Vanes .... the point about which way round is more to do with a used impellor than a new. Used has stressed its vanes and if you turn it round and force it the other way - you are likely to have early failure of a vane. A new impellor of course hasn't had the stress induced into it yet and can be fitted whichever way unless it's a handed one - rare.

 

[scottie]

water seals

there are ceramic seals normally used in circulating water pumps http://www.marinepartseurope.com/en/volvo-penta-explodedview-7745910-26-20331.aspx and this may be what the op was looking at. these are more prone to damage from grit and are designed to be use in a closed circuit system but usually left in raw water cooled system as they are the engines designed pumps .Oil seal is a generic term as they are not exclusive to use with oil but are an effectic method of sealing a rotating shaft

 

[Heckler]

Viton is Duponts registered name for what I think you'll find described as a "fluoroelastomer". That and nitrile rubber have "very good" resistance to oil and "good" resistance to water. Teflon (PTFE) has the best resistance of all to water.

The trouble is that no elastomeric material is ideal for use with water because it is a relatively poor lubricant.

The vitally important thing about the water seal is that it has stainless steel garter spring.

Pleased to hear that someone has proved that it does not matter which way the vanes are prefolded on the pump impeller. Can now answer all questions about it by saying it does not matter and do so with confidence.

Many years ago when I was doing night school in Denbighshire Tech I was taught that water is a good lubricant as long as there is plenty of it! So Vic I think that you need to do a bit more research!
Going on to the original post, when I used to do the yearly impellor change on my VP2030 I would carefully clean the crud out of the lip seal and replace with VP blue grease, this was a tip from the local VP dealer. It meant that I never had a prob with shaft marking etc, a comon fault on the early VP 30X0 series.
The yearly impellor change is no more now either, it is just a thumblethumbs practical car mechanics thing. I just take it out, bend the vanes etc and look for signs of deteriation. If ti looks good it goes back for another year. Sometimes on this forum we are all guilty off perpetuating urban myths and behaviours and sometimes it is good to step back and say Yep, that is ok instead of trying to show how clever we are and point out highly technical reasons for doing or not doing something. Personally "oil" seals are seals and will work equally well in water or oil, with the caveat that SS springs could be used to make sure that they last a bit longer, I would have no qualms at all about using a bog std with carbon steel springs one as a get you thru a fortnights trip!
Stu.

 

[Avocet]

...The vitally important thing about the water seal is that it has stainless steel garter spring.

Pleased to hear that someone has proved that it does not matter which way the vanes are prefolded on the pump impeller. Can now answer all questions about it by saying it does not matter and do so with confidence.

I think you can also get lip seals with bronze springs - which would also be OK.

With regard to the folding of the vanes on the impeller, I used to worry about that but in fact, every time I stop my engine, the vanes get folded back on themselves! Similarly if it fails to start and I let go of the starter, they fold back on themselves. As the piston comes up on the final compresion stroke, it can't get past TDC and "bounces" backwards down the bore. This reverses the direction of the engine and with it, the water pump (which is on the end of the crank on my engine). I even took the water pump cover off once and flicked the starter button because I couldn't believe it wouldn't damage the impeller! It really does go backwards for a bit and it really DOESN'T seem to bother the impeller!

 

[VicS]

I was taught that water is a good lubricant

Soddit! all that dosh I've wasted on oil over the years.

Even gone to the trouble of renewing the seals in the outboard gearbox to keep the water out. Should have cut some slots in the case to let more in!

The statement, "The trouble is that no elastomeric material is ideal for use with water because it is a relatively poor lubricant" came from a seal manufacturer ... better pass the info on to them.

My mistake I suppose; assuming the seal manufacturers knew anything about it.

 

[Heckler]

Soddit! all that dosh I've wasted on oil over the years.

Even gone to the trouble of renewing the seals in the outboard gearbox to keep the water out. Should have cut some slots in the case to let more in!

The statement, "The trouble is that no elastomeric material is ideal for use with water because it is a relatively poor lubricant" came from a seal manufacturer ... better pass the info on to them.

My mistake I suppose; assuming the seal manufacturers knew anything about it.

Miaoww!