I don't believe that flexibility has much to do with impeller performance. Once it's inside the pump it HAS to conform to the internal volume of the casing or break apart and the pump works solely on volume change for performance. Assuming clearances are in spec. When impellers fail, their blades break off and block up the heat exchanger. You can tell when this is about to happen - inspect the root of the impeller vanes and you will see axial cracks starting to develop. If the boat is not sailed all year, Mine isn't, I pull the impeller when winterizing and inspect it. If it looks good I use it again next season, if I see cracks at the vane roots it gets tossed. Either way, it doesn't stay inside the pump all winter. I think that (the vanes taking a set) going to shorten it's life or degrade performance more than anything.
sam :-) CnC 26 Liquorice Ghost Lake Alberta On 2012-10-19, at 9:45 AM, "David Blair" <dblair...@telus.net> wrote: > Had a little lesson about impellers. When Evangeline was new to me I had no > idea how long the impeller was in place; the water flow looked iffy although > there were no cooling problems. (Yanmar 3GM30). Took the impeller out and it > seemed fine but replaced it anyway and got markedly better flow volumes. > Aappearance of impeller, if intact, is probably secondary to the flexibility > of the vanes for function. So my rule now is “when in doubt replace” and > keeping the old one as a spare is questionable. > > Cheers > From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Sébastien > Lemieux > Sent: October-19-12 6:17 AM > To: cnc-list@cnc-list.com > Subject: Re: Stus-List Miscellaneous -impeller > > I don't have the experience of Rich but I would also lean in that direction. > I've changed mine for the first time this summer after 3 years. The impeller > looked in perfect condition (no cracks and blades were as flexible as a new > one). I kept the old one as a spare and now feel confident that I will only > inspect the impeller every spring. > > I've been told by a mechanic that if the raw water circuit is winterized > using antifreeze (vs. drained), the impeller holds up very well. Since our > impeller spends more than half the year in antifreeze, this might explain the > durability! > > I also reasoned that since we sail on a lake with no commercial traffic and > never solo there is little risk in case I have to face an impeller break > down: I have a spare and tools on board, I know how to swap them. > > Sébastien Lemieux > Merlot X - C&C 30 mk2 1987 > Mooney Bay - Lake Champlain > > > On Oct 18, 2012, at 21:28, Rich Knowles wrote: > > > I check mine each season's end when I winterize. If it looks good, it goes > back in. I have installed one new one in 15 years and that includes several > runs of a few minutes each year without water. They are pretty durable. I > check for cracking. > > Rich Knowles > Indigo. LF38 > Halifax > > On 2012-10-18, at 22:04, Martin DeYoung <mdeyo...@deyoungmfg.com> wrote: > > ...how often do you guys change the impeller in the raw water > pump? > > I change Calypso's 4-108 raw water impeller at the start of each season then > put the lightly used old one in the spares box. It is also my practice to > check the impeller prior to setting off on a longer trip where a sudden loss > of cooling might be inconvenient. > > There has been a year or so where I did not change the impeller in the spring > and the impeller perform fine with no significant change in appearance. > > I change the impeller after each time I forget to open the raw water inlet > thru hull valve and allowed the engine to run without cooling water for more > than a few minutes. > > Martin > Calypso > 1970 C&C 43 > Seattle > > -----Original Message----- > From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Robert > Abbott > Sent: Thursday, October 18, 2012 5:24 PM > To: cnc-list@cnc-list.com > Subject: Stus-List Miscellaneous > > Because of excessive mussel growth on my prop and prop shaft the past > several seasons, this past Spring I tried something new, namely applying > "lanolin" to them....boat was hauled this week and I can report that the > lanolin was not very effective.....there were approx. 3 dozen mussels > attached to the prop and the prop shaft was covered as well. > > On another note, applied Micron 66 antifouling paint to the boat this > past Spring (have been using Micron CSC for over 12 > years).....absolutely no growth of any kind....and specifically no > 'slime' which is common with the CSC.....the bottom looks like it did > when it was painted in the Spring and I only applied a very light coat > of the '66' (actually diluted it approx. 10%)....it is incredible > antifouling paint.....only regret is that it is not sold in Canada. > > And, after 7 sailing seasons, I decided to check the air filter on the > Yanmar 2GMF.....took the cover off to discover there was no 'actual > filter' in the metal casing...ooops! There will be by next Spring. > > Lastly, how often do you guys changedthe impeller in the raw water > pump? Not what the specs recommend but actually how often.....every > year, 2 years, 5 years, 10 years? > > Bob Abbott > AZURA > C&C 32 - 84 > Halifax, N.S. > > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com
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