Impeller bits

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Neil

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I was out on Sunday - beautiful day but cool and windless. I noticed that the raw water output was much reduced, such that the telltale peed only at high revs. Back at the Marina, I pulled the impeller to check it. Only three of the six vanes were present! What was likely to have happened to the broken off vanes?

I had a spare on board which I fitted, and it seems none the worse. Could they potentially block a waterway?
 
Hi Neil, they are lodged in your heat exchanger. I sorted the problem on my present boat by fitting a 45 degree mesh filter on the output side of the water pump going to the heat exchanger. At the bottom of the 45 deg angle, you can check/clean the filter. I have a 12 bladed impeller and I keep count of the lost blades... when I've counted 6, I change to a new impeller.. without having to dismantle the heat exchanger to retrieve the errant blades as they were all trapped in the filter... some folks will not agree with me but it works!!!

GL
 
Monique said:
Hi Neil, they are lodged in your heat exchanger. I sorted the problem on my present boat by fitting a 45 degree mesh filter on the output side of the water pump going to the heat exchanger. At the bottom of the 45 deg angle, you can check/clean the filter. I have a 12 bladed impeller and I keep count of the lost blades... when I've counted 6, I change to a new impeller.. without having to dismantle the heat exchanger to retrieve the errant blades as they were all trapped in the filter... some folks will not agree with me but it works!!!

GL
Click to expand...
Would be grateful if you would post a picture of your filter. Sounds like a good idea.

Www.solocoastalsailing.co.uk
 
Neil said:
I was out on Sunday - beautiful day but cool and windless. I noticed that the raw water output was much reduced, such that the telltale peed only at high revs. Back at the Marina, I pulled the impeller to check it. Only three of the six vanes were present! What was likely to have happened to the broken off vanes?

I had a spare on board which I fitted, and it seems none the worse. Could they potentially block a waterway?
Click to expand...

Do you have direct or indirect cooling system?

Www.solocoastalsailing.co.uk
 
>Could they potentially block a waterway?

Yes I had that problem when one broke off and had to take the off pipes and heat exchanger to find it, it was blocking the pipe into the heat exchanger. If the engnine is fine at the moment that may change so I would find the missing three.
 
Neil said:
I was out on Sunday - beautiful day but cool and windless. I noticed that the raw water output was much reduced, such that the telltale peed only at high revs. Back at the Marina, I pulled the impeller to check it. Only three of the six vanes were present! What was likely to have happened to the broken off vanes?

I had a spare on board which I fitted, and it seems none the worse. Could they potentially block a waterway?
Click to expand...

Depending on what engine you have it may be easy to find the missing blades. On the Volvo MD2030 which I have any missing blades will stay right before entering the heat exchange tubes. The little tubes are too narrow for the blades to go through. Once I remove the front rubber cover of the tube I can find everything there.
 
KellysEye said:
>Could they potentially block a waterway?

Yes I had that problem when one broke off and had to take the off pipes and heat exchanger to find it, it was blocking the pipe into the heat exchanger. If the engnine is fine at the moment that may change so I would find the missing three.
Click to expand...

Thanks for all the replies - I didn't think it through re the heat exchanger. It'll have to come out, so it looks like an early service is in order. I've just ordered some service spares, including new heat exchanger end cap O rings, as it happens.
 
I like the inline filter idea, too. I'm not sure I have room or the pipe length to do it but I'll have a look next time I'm down.

I think I'd be looking at 3/4 inch, or the metric equivalent of.
 
doug748 said:
Sounds like you could have a Beta engine fitted with a Johnson pump.
If so I recommend avoiding the Johnson impellers and fitting Jabsco replacements.
Click to expand...


Yes, and the replacement I put in (and the new one ordered) was a Johnson part. Do they have a poor longevity record? The engine was new in 2012, so the impeller has lasted 4 years. I may replace every couple of years, regardless.

Or every year?
 
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I had a couple of Johnson impellers and it always ended up as it did with you, or there was cracking evident, sometimes after 6 months use.
The Jabsco equivalents feel noticeably softer, none have cracked or broken for me and I have kept them a number of seasons. I have two used ones in my toolbox for backup, they look fine.

There was some talk, in another thread, that Johnson have changed their rubber composition but I won't be going back.
 
Neil said:
Yes, and the replacement I put in (and the new one ordered) was a Johnson part. Do they have a poor longevity record? The engine was new in 2012, so the impeller has lasted 4 years. I may replace every couple of years, regardless.

Or every year?
Click to expand...

Here is my opinion FWIW... if you want reliability and not face what you did, change the blimey thing yearly. Means peace of mind and reliability. If you went for 4 years, I'd stick with Johnson impellers... 4 years is great useage.

GL
 
Here is an example of a filter fitted after the pump where any broken pieces can be retrieved from.

vented-anti-syphon-loop.jpg
 
GaryCottam said:
Here is an example of a filter fitted after the pump where any broken pieces can be retrieved from.

vented-anti-syphon-loop.jpg
Click to expand...


Wow! This is very tidy. May I ask why do you have the seacocks before and after the racor filter? I would expect to see those on a double filter installation. Do you use them (I am only guessing now) when you replace the filter so you need to bleed the system less afterwards?
 
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