Impeller changes

[rlw]

Hi,

Up till now I have changed my impellers on my AD41 every season (less than 100 hours). This year due to lack of time I have not gotten round to it but am wondering wether replacing them every year is over the top.

I'd rather err on the side of caution than overheat an engine but I know several people that have run the same impellor for years. I was maybe looking at changing once every 2 seasons or so.

I'd be interested in the views of any other volvo owners out there.

Rob

 

[gjgm]

wondered too. Is it a volvo scan to make millions out of us?On the other hand I concluded that if I was an Engine manufacturer, I d probably recommend changing the consumables regularly, too. Some say taking it out over winter and storing in a bag so it doesnt risk turning brittle, should mean you can put it back in, in Spring. Some risk of the vanes getting a bit to permanently stuck in the same shape otherwise. That sounds a sensible inspection route too.

 

[Questor]

A short while back, I discovered ours had not been changed for probably 5 years.

On removal & examination, there was very little wrong with them - One vane had a small crack in it, that's all.

I'm sure 200 hours or so between changes is fine.

 

[DAVIDO]

Change mine every two years as with everthing else. We only do 60-70 hours a year (AD41s also).

 

[benjenbav]

Not absolutely sure when mine (AD41s) were last changed before this year because I have only had the current boat since May 2006. However when they came out you could have put them both back in the box and sold them as new.

 

[peterb26]

Same as Questor. Our 5 year old one in a previous boat was absolutely perfect.

 

[Sixpence]

when it's working , one small crack can soon grow to a big crack , then that vane breaks off and the rest go too , usually at the worst time

 

[DAKA]

I used to change my Volvo impellers in my ad41s every season.
they were bent and deformed with hairline cracks in odd places.

I then bought a set in France that were Neoprene.

I took them out and checked them every year but they did not show any signs of wear and went back in after layup.

Volvo impellers are Nitrile based and are hard, they will take a higher temperature but they should only pump cold raw water so in my opinion the Neoprene impellers are more suitable for the average pleasure boater in fact I cant think of an application where nitrial based impellers should work better.......anyone use their boat near Larva flows /forums/images/graemlins/confused.gif

Check out the Jabsco website and fit cheaper neoprene impellers that will last for well over 2 seasons

http://www.jabsco.com.au/impeller_select.pdf

 

[Powersalt]

good point. I happened to visit the boat last year as the annual service was being done. THink ahead I asked the engineer if I could have the old impellers as a spare. He gave me one and showed me the other as nackered. These are changed every year and I only do about 25 hrs a year. So I dont think there is any firm advice other than play safe and change them

 

[hlb]

Think it depends on what sort of boating you do and what you want to put up with, if it goes pear shaped. But as said above. One nick in a vane can soon knacker the lot up. Main thing is to have a spare one. It's not that big a job to replace. Less course it goes at the wrong time.

 

[duncan]

well on my Yanmar I pulled it at 600 hrs as scheduled and it was imaculate apart from the damage I had caused getting it out..............on the other hand the pump casing plate was well gone and definitely required replacing (probably at 400hrs).

given that you are paying more to have it replaced than it's cost on most installations I belive this is why they are 'routinely' changed.

 

[DAKA]

[ QUOTE ]
well on my Yanmar I pulled it at 600 hrs as scheduled and it was imaculate

[/ QUOTE ]

Out of interest do you know if it was Nitrile or neoprene ?

Nitrile-Hard, stays deformed when out

Neaprene-soft, almost reshapes when out, warm to touch and easier to fit.


Yamar maybe fit Neoprene as standard ?

 

[duncan]

not hard - still soft last week over a year after being removed

 

[Andrew_Fanner]

Used to change every couple of years, check every six months or so (Speedseal so it was easy) and carry 2 spares.

 

[rlw]

Thanks for the feedback. When I bought my Portofino I knew nothing about these engines and just ran for the first season as everything worked. I had one go bust on me at the end of the season and saw how fast the temperature rises when it starts to break. After that I changed it religiously. And have done on the M38 now for the last few years. Summer hols will hopefully see some sea cruising along the Belgian coast so I might just do it for peace of mind.

As for replacing them a trick a learn from my local tech is to squirt some form of lube in the strainer and then turn the engine over. Unsticks the impeller and it slides out much easier.

Rob

 

[scubaman]

We've changed the impeller every year on our previous boat and on several occations one or more of the wings have been cracked. I suppose that an impeller will be ok for several seasons if conditions remain 'normal'.

Impellers don't like to be run dry. Still, this can easily happen eg. during winterizing the engine (while flushing the engine with fresh water) or when picking up leaves and blocking raw water strainers, etc. Little things like these can quickly weaken the impeller with extremely irritating consecuences.

We spent two days hunting down pieces of an broken impeller two months ago and that wasn't nice /forums/images/graemlins/mad.gif Luckily no further harm was caused to the engine by the broken impeller, but the results could have been much worse.

I find changing impellers regularily a cheap insurance against much pain if things go wrong.

 

[[2068]]

imho, It's just not worth economising on.

I change every season, and there's always a small crack in a vane somewhere. Little crack becomes bigger crack, which means a bit breaks off and winds up in heat exchanger or exhaust sprayer... lots of hassle. Less hassle to change every 12 months.

dv.