PBO Shredded Impellor article

[pyrojames]

The line in PBO's Facebook article on impellors ‘Years of shredded water impeller bits had clogged the pipe’ seemed very odd to me. I check my impellor occasionally (about every 2 years). It gets changed even less, and on no occasion has it had bits of it missing. Is this unusual, or is something else going on in the PBO's case?

Or have I just jinxed myself....

 

[Praxinoscope]

I have had a few bits go missing off an impeller over the years, but I would guess if it is a regular occurrence and in some quantity a serious inspection of the impeller housing is called for.
What the bold type in the OP doesn't indicate is whether there was a raw water filter between the inlet and the impeller, if no filter the any amount of 'nasties' could enter the system and wreck the impeller.

 

[Neeves]

We have been servicing our Volovos fairly religiously about every 50 hours and occasionally one or two of the 'fins' of the impeller have had a crack. This has been sufficient warning to continue to check the impeller, along with changing the filters etc. The warning has also been sufficient to change the impellor at every 50 hours (approximately). I am sure if we left the impeller unattended the fin would break loose and make its way through the cooling system, causing untold heartache on its travels. Really servicing an engine (we have 2) is not onerous - but very mucky - and would be best conducted by trained monkeys. Impellors, filters and oil is really not expensive (well it is but that's one of the penalties of yacht ownership (and more expensive if you do not compete the task yourself).

But if we lost a fin - I'd search through the system to find it - it cannot go far. Or if you search properly and do not find it - its gone. But we would not have lots of bits and pieces - as every fin, or part of, lost would be searched for exhaustively.

To find parts from previous impellers suggests to me - poor attention to detail.

but this not to criticise the author - if it was a second hand yacht - maybe the fault lay down (or is it 'up') the line of owners. If I were buying second hand I would want to see sight of an invoice from a professional of a recent service - or when I took ownership I would be checking (and changing the oil and filters etc).

Jonathan

 

[Neeves]

We have been servicing our Volovos fairly religiously about every 50 hours and occasionally one or two of the 'fins' of the impeller have had a crack. This has been sufficient warning to continue to check the impeller, along with changing the filters etc. The warning has also been sufficient to change the impellor at every 50 hours (approximately). I am sure if we left the impeller unattended the fin would break loose and make its way through the cooling system, causing untold heartache on its travels. Really servicing an engine (we have 2) is not onerous - but very mucky - and would be best conducted by trained monkeys. Impellors, filters and oil is really not expensive (well it is but that's one of the penalties of yacht ownership (and more expensive if you do not compete the task yourself).

But if we lost a fin - I'd search through the system to find it - it cannot go far. Or if you search properly and do not find it - its gone. But we would not have lots of bits and pieces - as every fin, or part of, lost would be searched for exhaustively.

To find parts from previous impellers suggests to me - poor attention to detail.

Jonathan

 

[vyv_cox]

Probably the main cause of impeller vane loss is insufficient water passing through the pump. When we transited the Canal du Midi our inlet blocked countless times due to ingested leaves stirred up from the bottom. I needed to change impellers several times.

 

[Jim@sea]

I bought a boat with a Yanmar Diesel Engine. A service sheet said that when the engine was last serviced 50 hours before the Impeller was "serviceable"
But with this boat getting to even see the impeller was very difficult as it was squeezed into the engine bay.
Knowing that a boatyard would not pass up on charging for a new Impeller I wondered though if the mechanic was on a fixed fee for the service and could not be bothered to change it.
Anyway I had a marine engineer put a new one in, and he had to take lots of stuff off the engine to actually get at the impeller.
It was perished, virtually every rubber vane had cracks at the base.
Had I gone to sea with the boat the impeller would have failed.
Just as rubber cam belts fail after 3+ years even if the car has done little mileage, impellers are subject to age related failure. Plus even if you have one fitted how long was it on the shelf at the boatyard before it was fitted.

 

[NormanS]

I only sail for six months in the year, and then lay up. At lay up, the impeller is removed, inspected, and if OK gets to sit on a shelf for its winter holiday. ? It then goes back into the pump before the first run of the engine, which takes place while still ashore.
If parts do come off an impeller they will almost inevitably land up at the seawater entry to the water cooler - best avoided.

 

[scottie]

From previous experience as a service dealer the cost of sorting out a faulty one was a strong persuasion to routinely changing rather than putting a used one back in

 

[Momac]

Or have I just jinxed myself....

Probably yes.

Annual check for me in the spring. Sometimes the impeller is no good and sometimes it lives to fight another year .
The port engine seems harder on impellers for no apparent reason

 

[BabaYaga]

I only sail for six months in the year, and then lay up. At lay up, the impeller is removed, inspected, and if OK gets to sit on a shelf for its winter holiday. ? It then goes back into the pump before the first run of the engine

I have the same routine. My engine is now 15 years old and I have changed impeller twice. First time after 7 years, despite the fact that the impeller was still looking fine. Last year I changed again as, to my great surprise, one of the vanes had a crack at the base.
Low annual engine hours, though.

 

[bitbaltic]

From previous experience as a service dealer the cost of sorting out a faulty one was a strong persuasion to routinely changing rather than putting a used one back in

That’s my approach, it’s changed annually (by the yard) whether it needs it or not.

the engine has one job which is to always work when needed for as long as needed. Preventative maintenance is the way to achieve that.

 

[Plum]

I had an impeller blade crack at the base after 60 hours which I luckily found while fitting a new shaft seal. I sent an email to supplier ASAP Supplies who said it was likely to be a weak spot from manufacturing and sent me a new one. That is the only impeller problem I have had in 40 years. I replace them at 150 hours intervals.

Www.solocoastalsailing.co.uk

 

[zoidberg]

Given that damaged and disintegrated impellers seem to be common occurences, with bits ending up in the heat exchanger piping, would it make sense to fit a 'bits trap' something like this into the supply pipe between the impeller/pump output and the engine? What do the engineers say?

 

[Praxinoscope]

I only sail for six months in the year, and then lay up. At lay up, the impeller is removed, inspected, and if OK gets to sit on a shelf for its winter holiday. ? It then goes back into the pump before the first run of the engine, which takes place while still ashore.
If parts do come off an impeller they will almost inevitably land up at the seawater entry to the water cooler - best avoided.

The only addition to the above that I now perform is to rub a small amount of silicon grease into the impeller before storing it for its Winter holiday, to date never had an impeller problem since I started this routine.

 

[vyv_cox]

Given that damaged and disintegrated impellers seem to be common occurences, with bits ending up in the heat exchanger piping, would it make sense to fit a 'bits trap' something like this into the supply pipe between the impeller/pump output and the engine? What do the engineers say?

Seems like a perfectly sound idea provided the strainer body is rated for the pump discharge pressure. Strainers are normally located upstream of pumps, where they require little pressure capability.

 

[lynallbel]

I bought a boat with a Yanmar Diesel Engine. A service sheet said that when the engine was last serviced 50 hours before the Impeller was "serviceable"
But with this boat getting to even see the impeller was very difficult as it was squeezed into the engine bay.
Knowing that a boatyard would not pass up on charging for a new Impeller I wondered though if the mechanic was on a fixed fee for the service and could not be bothered to change it.
Anyway I had a marine engineer put a new one in, and he had to take lots of stuff off the engine to actually get at the impeller.
It was perished, virtually every rubber vane had cracks at the base.
Had I gone to sea with the boat the impeller would have failed.
Just as rubber cam belts fail after 3+ years even if the car has done little mileage, impellers are subject to age related failure. Plus even if you have one fitted how long was it on the shelf at the boatyard before it was fitted.

Many cambelts are 10 yrs or 100 plus k now.

 

[Daydream believer]

When i first purchased my boat, new, I needed 4 new impellors in the first 2 years. Hence I always have several spares. Since then I have had 2 failures at sea & I often change at the start of the season; having removed the old one at the end of every season, when I drain off any excess water where possible. There does not seem to be any correlation between time, use & wear. What I have noticed though, is that it is no point buying non Volvo ones. Some do not fit properly & most wear out quickly. So it is worth sticking with genuine Volvo part for this item. My engine has done 5000 hours.

 

[DownWest]

When i first purchased my boat, new, I needed 4 new impellors in the first 2 years. Hence I always have several spares. Since then I have had 2 failures at sea & I often change at the start of the season; having removed the old one at the end of every season, when I drain off any excess water where possible. There does not seem to be any correlation between time, use & wear. What I have noticed though, is that it is no point buying non Volvo ones. Some do not fit properly & most wear out quickly. So it is worth sticking with genuine Volvo part for this item. My engine has done 5000 hours.

That sounds a lot on a new boat? How many hours did you do in that time?

 

[Daydream believer]

That sounds a lot on a new boat? How many hours did you do in that time?

approx 5-600 from memory. Motored all the way down the French coast into bay of Biscay ( wife on board). Then spent 12 weeks in Dutch canals for starters

 

[Wansworth]

I bought a boat with a Yanmar Diesel Engine. A service sheet said that when the engine was last serviced 50 hours before the Impeller was "serviceable"
But with this boat getting to even see the impeller was very difficult as it was squeezed into the engine bay.
Knowing that a boatyard would not pass up on charging for a new Impeller I wondered though if the mechanic was on a fixed fee for the service and could not be bothered to change it.
Anyway I had a marine engineer put a new one in, and he had to take lots of stuff off the engine to actually get at the impeller.
It was perished, virtually every rubber vane had cracks at the base.
Had I gone to sea with the boat the impeller would have failed.
Just as rubber cam belts fail after 3+ years even if the car has done little mileage, impellers are subject to age related failure. Plus even if you have one fitted how long was it on the shelf at the boatyard before it was fitted.

Not very good engine design ?