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View Poll Results: How often do you replace the impeller on your raw water pump?
Once a year, or more frequently, depending on engine hours 19 10.98%
Once every two years 59 34.10%
Once every three years, or more 50 28.90%
Only after it fails 21 12.14%
I've never replaced it 24 13.87%
Voters: 173. You may not vote on this poll

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  #1   IP: 75.210.87.216
Old 08-12-2007, 11:18 AM
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How often do you replace your impeller?

I'm a little surprised this hasn't been mentioned...
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  #2   IP: 4.243.25.157
Old 08-15-2007, 03:38 AM
starnesent starnesent is offline
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ive never done it -

yes im Les & im an

impeller virgin - :O

my sisters sailboat has an A-4 a 70's model.
the A-4 is in a 29' Islander very nice boat.
great shape,but unused as a sail boat. it was bought to live on.
& there it sits ~ well docks. . .

I'm going to either put in a new pump & rebuild the original -
Or convert it to FWC & then maintain that impeller
& yes i will be sure to replace the impeller ever 3 or so years no matter what the hours it actually runs. as the impellers look to be made of material that might deteriorate with age. The FWC pump would be right up front easy to maintain compared with the location of the RAW water pump up & under & behind the starter & Alternator & over & under a hump of fine looking {but} hard teak.

oh why fix a boat tat don't actually sail you ask (?)
we are trying o get her to sell it as she never
sails it.

yup

* shucks i have to fix the RAW water pump anyway.
ppl in the know [Don] informed me the FWC still makes use of the RAW water to cool the FWC tank
[that makes good sense] so i need to get the new pump from moyer & while im at it a new impeller for the old pump
to get it in running shape in case its needed on the dock (?)
yup another 350 mile drive - shucks id rather pay someone to do it right.

Last edited by starnesent; 08-23-2007 at 12:19 PM. Reason: update
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  #3   IP: 69.29.217.249
Old 08-22-2007, 11:54 PM
brad@elevated.org brad@elevated.org is offline
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I've learned my lesson

I learned my lesson on our last cruise. My impeller was in for just at two years--maybe 50hr of engine time. When I stopped at our first destination I found 2 out of 8 fins remaining I retrieved 4. Two days later I blew a head gasket. Coincident?

They are relatively cheap and easy to change, at least on my a4. I may change it every time I go out!
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  #4   IP: 38.118.52.41
Old 08-23-2007, 06:34 AM
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Brad,

The only way I see your head gasket failure relating to your impeller failure is if the engine severely overheated and you still had one of the older (paper) head gaskets installed. With the advent of the Victor steel-reinforced graphite head gaskets in the early nineties, head gasket failures have reduced to almost zero for any cause, including overheating.

Don
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  #5   IP: 24.47.216.175
Old 09-01-2007, 09:24 PM
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Up here in the northeast I like to check our cooling water impellor every spring and make sure to drain all the liquid out of it in the fall. I also carry a spare and check to make sure there is water flowing out the exhaust every time the engine is started.
I learned to be diligent about this crucial piece of equipment after launching in our second season. At that time I did not even know that the water pump had a thing called an impellor and left liquid in there that probably froze. I went out on a windy day and the engine overheated while we were bobbing about in 3' swells in a mooring field in LI Sound. I have vowed to never allow myself to be in that position again.
Also, be very careful when running your A4 while on the hard and always
ensure that there is cooling water available and that it is being pumped out the exhaust pipe. Never put your engine in gear while on the hard; the cutlass bearing expects water to be there to lubricate the shaft as it turns.
Live and learn.
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  #6   IP: 142.68.126.98
Old 12-31-2008, 06:07 PM
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On the big twin power boat we had for a decade, I changed them annually, owing to a bad experience first year or two and a fair bit of summer cruising. For this smaller engine, I like Don's advice from the MMI pump instruction kit, and I dreamed up some additional reasons to change the impeller. Here is my personal checklist:

1. Fins appear stiff, cracked, have a pronounced "memory" (bent lobes), or any other sign of damage.
2. Every two years of average summers in clear water.
3. Every 200 hours (= 800-1000 miles under power), more often in sandy water.
4. Episode of running pump dry more than a few seconds (during startup, or episode of clogged strainer).
5. Episode of engine overheating, regardless of cause.

Remove impeller every fall and put it back in every spring, so the vanes do not remain bent up all winter (leave a reminder somewhere obvious for spring). The new MMI pump makes removal a snap.
Carry at least one spare.
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  #7   IP: 96.229.195.76
Old 07-10-2012, 10:26 PM
Dave Neptune Dave Neptune is online now
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Not often enough??

I'm in the 3 or more. I usually don't touch until I notice reduced flow and a temp rise.

Dave Neptune
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  #8   IP: 12.216.194.200
Old 09-05-2012, 10:31 AM
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I would also be in the 3 or more years crowd, but I generally put less than 30 hours per season on the A4
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  #9   IP: 24.224.206.117
Old 10-21-2012, 08:49 PM
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Smile

I'd be thinking every 2-3 yrs.....and I have to add that to my checklist I have going....see, something else I forgot.
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  #10   IP: 206.125.176.5
Old 12-06-2012, 10:01 AM
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Back in 2010, I see JOhn Cookson commented that he stores his impellers in an airtight bag.

I do the same thing..ziploc bag, & also a scrap of rag soaked in MMO to keep it moist.

Thinking back, I replaced the impeller in the pump in Jan 2009 when I rebuilt the pump...so I guess I am 3 years or more as well..

Probably time to do it again.
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Last edited by sastanley; 12-09-2012 at 06:27 PM.
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  #11   IP: 24.224.152.244
Old 12-11-2012, 02:40 PM
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New spare as well.

Pulled mine last spring and it was still flexible so I left it in. Mine has 3 yrs on it now as well but I have a couple of spares in the box. The thing I don't usually do is keep used gear around for an emergency. Once I change out a new spare for sure.
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The pessimist complains about the wind.
The optimist expects it to change.
The realist adjusts the sails.
...Sir William Arthur Ward.
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  #12   IP: 67.186.97.244
Old 06-13-2018, 04:13 PM
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In Chicago I change mine [oberdofer] every 3 seasons, about 60 -75 hrs total on early model A4 I always [slowly and carefully] take the impellor and shaft out over winter layup and find this extends its' useful life. [rounded off - deburred the shaft edges so not o damage bushings] Always order a new spare and keep recent old one as emergency backup. Inspect, lightly lube and carefully reinstall in spring. Never had a impellor problem in 40+ yrs and am on only my second water pump. I have fairly decent access so job is not too difficult. A couple of times my backup has gone into someone else boat when there fins have cracked off.
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