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Old 01-08-2012, 00:06   #31
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Quote:
Originally Posted by Therapy View Post
You use the term "reco,d"

That means reconditioned right?

If so that would include any bearings and seals (and maybe the shaft) in addition to the impeller.

Most here are talking about impeller change and not a recondition.

Rebuild is another term I use that basically means the same thing.

What do you actually mean?
reco meant pulled the pump off checked the shaft for pitting (none)replaced the inner and outer seals replaced the copper squeeze plate replaced the impeller, while i was at it replaced all the hosing and pumped hydrochloric acid through the engine cleaned everything and put it all back together. My main concern is the shaft which gets pitted if the outer seal goes, i check the impeller etc about as regular as i change the anodes. I'm wondering how often i should replace the seals etc.
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Old 01-08-2012, 00:10   #32
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

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Originally Posted by GordMay View Post
Additionally, having recently replaced his impeller, Capt B is MUCH less likely to actually encounter this type of situation.
Exactly.

And you can carry on about reconditioning and try to confuse the issue etc, but just getting the bloody engine to run so we can get into the bloody harbour is what we're talking about here.

Cap'n B probably has a collection of 10 ton Sarca's, CQR's, Bruces (maybe not Rocna's?). And he'll only need to use it for 10-15 minutes as that's how long an impeller replacement takes if it's a familiar task.

Same-same for filters, belts etc etc. Self-reliance is critical for yachties.
If you're not handy, you shouldn't bother with a yacht.

lockie
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Old 01-08-2012, 04:43   #33
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Cautionary tale:
Impellers do fail. I was sitting at the quay in Papeete happily recharging batteries with engine running. (1977). Guy walks down the quay and says " no water coming out, mate". He helped me change the impeller--no damage done. It was one of those English taxi diesel engines we had in that boat. (Perkins?) No idea of impeller make.
Fastforward 2009. 2,000 miles offshore Chile-Gambier and I start engine after 2 weeks of battery charging via solar magic. No water coming out exhaust. I start at sea water through hull and check everything downstream. No garbage bags clogging, all hoses attached properly, all looking normal. Must be impeller. Change impeller. (not easy on my boat. Yanmar has impeller housing mounted facing aft so I must use mirror for everything). Not worried, I was a dentist before I started changing impellers and have always done everything backwards. Had no impeller-puller so used 2 screwdrivers to pry out impeller. The impeller looked great when I got it out except for the scars left by steel screwdrivers on rubber. Pitched impeller overboard, installed new one and water flow was normal.
Happened twice afterward and I came to realize I had an air lock problem. Only after rough seas and no engine run for days. Undoing the sea water (Groco) strainer released the 'lock' and all goes well after that simple operation. Why do 'air locks' occur? Don't know, don't care. Know how to check it and release air block/lock.
I change impeller when it's convenient (on the hard) and watch water outflow from exhaust/water port carefully at each engine startup.
I have since purchased and impeller puller and have a box full of impellers. I do use an infrared temp gun on all main engine parts, regularly.
Pete
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Old 01-08-2012, 06:00   #34
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Quote:
Originally Posted by rigormortis View Post
Cautionary tale:
Impellers do fail. I was sitting at the quay in Papeete happily recharging batteries with engine running. (1977). Guy walks down the quay and says " no water coming out, mate". He helped me change the impeller--no damage done. It was one of those English taxi diesel engines we had in that boat. (Perkins?) No idea of impeller make.
Fastforward 2009. 2,000 miles offshore Chile-Gambier and I start engine after 2 weeks of battery charging via solar magic. No water coming out exhaust. I start at sea water through hull and check everything downstream. No garbage bags clogging, all hoses attached properly, all looking normal. Must be impeller. Change impeller. (not easy on my boat. Yanmar has impeller housing mounted facing aft so I must use mirror for everything). Not worried, I was a dentist before I started changing impellers and have always done everything backwards. Had no impeller-puller so used 2 screwdrivers to pry out impeller. The impeller looked great when I got it out except for the scars left by steel screwdrivers on rubber. Pitched impeller overboard, installed new one and water flow was normal.
Happened twice afterward and I came to realize I had an air lock problem. Only after rough seas and no engine run for days. Undoing the sea water (Groco) strainer released the 'lock' and all goes well after that simple operation. Why do 'air locks' occur? Don't know, don't care. Know how to check it and release air block/lock.
I change impeller when it's convenient (on the hard) and watch water outflow from exhaust/water port carefully at each engine startup.
I have since purchased and impeller puller and have a box full of impellers. I do use an infrared temp gun on all main engine parts, regularly.
Pete
If you are getting air locks with new impellers, your pump is worn and needs replacing or reworking. One race to Hawaii, we had this problem and found that we could avoid the air lock by closing the thru hull before we shut the engine down and opening it up again after we started it. Of course, we replaced the pump after getting to port.
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Old 01-08-2012, 06:33   #35
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

I have not changed my boat impeller in over five years. Of course that's because I converted to electric propulsion in 2008. No pump, no impeller, no problem. Even shut off the raw water seacock! Because of my engine placement changing the impeller was real PITA! So it did not get done every year but, I did keep an on the exhaust making sure there was adequate water flow. Which I found out was not always the best indication of impeller integrity. Before I canned the diesel I did install a Speed Seal cover on the water pump which I thought would make future impeller changes much easier:
THE BIANKA LOG BLOG: Lessons learned: The raw water impeller.
But, I never did get to try it as I pulled the diesel engine and went electric which has turned out to be a much more pleasant experience.
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Old 01-08-2012, 08:42   #36
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

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Originally Posted by lockie View Post
Exactly.

And you can carry on about reconditioning and try to confuse the issue etc, but just getting the bloody engine to run so we can get into the bloody harbour is what we're talking about here.

Cap'n B probably has a collection of 10 ton Sarca's, CQR's, Bruces (maybe not Rocna's?). And he'll only need to use it for 10-15 minutes as that's how long an impeller replacement takes if it's a familiar task.

Same-same for filters, belts etc etc. Self-reliance is critical for yachties.
If you're not handy, you shouldn't bother with a yacht.

lockie
I don't think so.

See post 31.
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Old 01-08-2012, 08:56   #37
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

We change the impeller every other oil change (500 hours) and have not had one fail yet.
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Old 02-08-2012, 11:04   #38
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Horses for courses. I never changed mine for 10 years and yes, I liveaboard and cruise regularly. I have a Speedseal fitted and two spare impellers, it's only a 5 minute job. I've had this boat 25 years and rebuilt the raw water pump twice. a wee tip, if you coat the impeller with washing up liquid it make's it very easy to fit.
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Old 02-08-2012, 11:53   #39
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

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. . . increases the probability that my boating days will involve boating and not repairs.
A day without boat repairs??


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Old 02-08-2012, 12:32   #40
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

An earlier post referred to an Impeller Puller. I first saw this puller at the Annapolis Boat Show but felt the $40 was too much. After struggling again to get the impeller out by levering dental picks and little screw drivers ...I found the company through an magazine advertisement and ordered it.

Pulling an impeller now is simple!!! As a Watch and Clock Repair person, I know having the correct tool not only simplifies the task, but also helps to prevent unwanted damage while doing the job. This puller allows me to change the impeller every year because it is now a simple task.

Bill
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Old 03-08-2012, 09:06   #41
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

A pair of angled long nose pliers does the job a treat also. I should have said in the earlier post, if you coat the splines of the impeller shaft with waterproof grease, then the rubber impeller vanes in washing up liquid the whole jobs done in 10 mins, then you can sit out on the back deck with a self congratulary gin and tonic.
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