Raw Water Impeller, Remove or Not

[GAJ52]

I have just winterised my boats engines with antifreeze in the raw water system. I have read some people recommend removing the raw water impeller to prevent distortion when the boat is not used over the winter.

Just wondering if this is a good thing or not necessary ?

 

[[70521]]

I have just winterised my boats engines with antifreeze in the raw water system. I have read some people recommend removing the raw water impeller to prevent distortion when the boat is not used over the winter.

Just wondering if this is a good thing or not necessary ?

I leave mine in, but only recored 25 engine hours last season.

 

[Phoenix of Hamble]

remove.... they end up distorted if left in for too long... and its a good chance to check it for cracks and general wear at the same time.

 

[vyv_cox]

I have suspected for some time that the 'distorted vanes' story is another of those myths that we have come to accept as fact. Having worked quite a lot with elastomers over the years, I find that distortion and compression set is rarely a problem with those of lower hardness, of which impellers are a good example. To test my theory I have deliberately left my impeller in the pump. It has now completed its second season of about 150 hours and is in its second winter, during which time I have not removed the cover.

I would add that I could not have done this before I had a Vetus strainer above the pump, ensuring that the impeller never runs dry. In the days when the pump drew water up from a lower strainer it would never have lasted a season without problems.

 

[Spirit of Glenans]

I have suspected for some time that the 'distorted vanes' story is another of those myths that we have come to accept as fact. Having worked quite a lot with elastomers over the years, I find that distortion and compression set is rarely a problem with those of lower hardness, of which impellers are a good example. To test my theory I have deliberately left my impeller in the pump. It has now completed its second season of about 150 hours and is in its second winter, during which time I have not removed the cover.

I would add that I could not have done this before I had a Vetus strainer above the pump, ensuring that the impeller never runs dry. In the days when the pump drew water up from a lower strainer it would never have lasted a season without problems.

Is that a standard strainer, similar to the one on the raw water feed side to the pump?

 

[alahol2]

I always remove mine for the winter for several reasons... a) I want to inspect it for cracks etc so it has got to come out. b) It may distort (so why risk it?) c) I may want to run the engine for a short while when ashore, with the impeller out I don't risk running it dry.
When re-installed at the start of the season it gets a thin smear of silicone grease to protect it until it has drawn water.

 

[vyv_cox]

Is that a standard strainer, similar to the one on the raw water feed side to the pump?

Yes, about four inches high and similar diameter. Vetus recommend fitting it about 6 inches above the pump. In my case it replaced one that was combined with the seacock that was some height below the pump. Installed correctly the pump never runs dry.

 

[NormanS]

I always take mine out for the winter. It takes less than five minutes, and lets me give it a thorough check.

 

[bert49uk]

Never take mine out in winter but do put a new one in just before re floating in the spring

 

[sailorman]

I have suspected for some time that the 'distorted vanes' story is another of those myths that we have come to accept as fact. Having worked quite a lot with elastomers over the years, I find that distortion and compression set is rarely a problem with those of lower hardness, of which impellers are a good example. To test my theory I have deliberately left my impeller in the pump. It has now completed its second season of about 150 hours and is in its second winter, during which time I have not removed the cover.

I would add that I could not have done this before I had a Vetus strainer above the pump, ensuring that the impeller never runs dry. In the days when the pump drew water up from a lower strainer it would never have lasted a season without problems.

Just serviced my engine this afternoon. took the impeller out,checked visually the pump surfaces. impeller ok so just reversed it & popped it back. we do stay afloat in the forlorn hope of a sail

 

[cryan]

In my experience you generally do more harm by disturbing them. Commercially you would expect a Jabsco style rubber impeller to last in excess of 1000 hrs. You wouldn't expect them to dry out and crack for at least a couple of years in rarely used standby engines such as fire pumps. carry a spare and if it does fail its a five minute job.
BTW they will work happily with a couple of fins missing. I pulled one out on an old bunker barge that just had one fin left bravely working away like a little trojan. flow was reduced but not non existent.

 

[Tranona]

BTW they will work happily with a couple of fins missing.

It is what happens to the missing bits that is the problem. Often end up blocking the tubes in the heat exchanger. Not a 5 minute job - neither is replacing the impeller on some installations.

 

[cryan]

It is what happens to the missing bits that is the problem. Often end up blocking the tubes in the heat exchanger. Not a 5 minute job - neither is replacing the impeller on some installations.

As I said, commercial. Usually bigger tube nests and fins just disapear over the side.
My point being that in a leisure environment I wouldn't think you should have to worry about them for a good couple of years at least.

 

[l'escargot]

I've never winterised an engine or removed the impeller - but I do stay afloat and start the engine at least every 3 to 4 weeks.

 

[robertj]

Yes, about four inches high and similar diameter. Vetus recommend fitting it about 6 inches above the pump. In my case it replaced one that was combined with the seacock that was some height below the pump. Installed correctly the pump never runs dry.

Where is it situated vyv?
I have a Bukh 24

 

[NormanS]

As I said, commercial. Usually bigger tube nests and fins just disapear over the side.
My point being that in a leisure environment I wouldn't think you should have to worry about them for a good couple of years at least.

So, are you opposed to preventative maintenance?

 

[sailorman]

So, are you opposed to preventative maintenance?

it would depend how much reserve the h/e has designed into it. some engines it seems have heat exchangers that are "only just" doing the job, any blockage becomes critical

 

[vyv_cox]

Where is it situated vyv?
I have a Bukh 24

Not quite sure you would get it in with the Bukh. We gained a great deal of space by replacing our 20 with a Yanmar.

 

[rosssavage]

Inspect annually, replace every two years. Left in all the time except for the 5 min annual lookie see.

Got some lovely Johnson ones to replace the usual Jabsco, which did three years before I chickened out and replaced them!

 

[robertj]

Not quite sure you would get it in with the Bukh. We gained a great deal of space by replacing our 20 with a Yanmar.

Blimey, just goes to show how big the Bukh is as there's enough room for a life raft in there too!
Regarding a previous question about the pss shaft seal vyv, where have you routed your vent tube?