D6 Impeller change, Lifespan, recommended change, safeside. ?

[hullabaloo]

How often do you change your impellers?
I prefer prevention over cure, and after two years, I wonder if I should change them on my d6 engines.

 

[westernman]

How often do you change your impellers?
I prefer prevention over cure, and after two years, I wonder if I should change them on my d6 engines.

The operators manual says check every 200 hours or every year which ever occurs first.
Is says nothing about replacement.

I would change every 400 hours or 4 years which ever occurs first unless used often in muddy water.

And at any sign of wear or degradation when inspecting or when run dry or with inadequate raw water flow (e.g. you left the raw water sea cock shut ;-)

 

[kashurst]

I tend to agree with Westernman. Impellers are very tough. They don't last forever bt they do last longer than magazines etc would have you believe.
I change mine about every 4 - 5 years and even then they look good.

 

[Paul1962]

I tend to agree with Westernman. Impellers are very tough. They don't last forever bt they do last longer than magazines etc would have you believe.
I change mine about every 4 - 5 years and even then they look good.

Agreed but some sea water pumps are nightmares to get at so if you are going to inspect - you may as well change.

You can also check the other items in a sea water pump like bearings and seals etc

 

[ss2016]

I have been wondering if the first start of the season is when impeller damage occurs. Does anyone think its worth pouring water into the D6 strainer before that first start with last year's impeller?

 

[westernman]

I have been wondering if the first start of the season is when impeller damage occurs. Does anyone think its worth pouring water into the D6 strainer before that first start with last year's impeller?

Just before the start of the season would be a good time to do your yearly check. Then when you put it back in smear it with a little glycerine (like what it says in the operators manual), then no problem for a minute before the water flows.

 

[ss2016]

My D6-400A-G service manual says change it at 200hrs 2years whichever comes first. It does not include the impeller on the annual check. My approach is to follow VP closely, hence the query.

 

[SC35]

D4-260 - I change them every two seasons.

 

[SC35]

I have been wondering if the first start of the season is when impeller damage occurs. Does anyone think its worth pouring water into the D6 strainer before that first start with last year's impeller?

The pump should self prime within a few seconds, so I don't do that.
But I do keep a close eye on the strainer lids to make sure that it has self primed on the first start after launch.

 

[oldgit]

In a MoBo.
On a cost to damage/grief ratio the impeller must be way out out in front of everything by by a hugh margin.
A replacement unit probably would cost most folks not much more than £50.00 to £100.00.
Final collapse is usually at the most inoppotune moment and invariably at the most awkward time.
Leaving you , if lucky in the middle of nowhere and if unlucky with a seriously fried engine as well.
Good luck with getting all the bits out from inside your cooling system as well.
For most boats/skippers replacing an impeller when halfway on a trip will be well nigh impossible, if you can even see or get to the location of the water pump.
If you have never had your day ruined by a temperature alarm going off underway you simply have not been boating long enough.
Change them on regular basis or suffer the crawl of shame as you return to your destination on one engine at 5 knots, with the fun of getting back into the berth on single engine, with your seriously annoyed "crew"

​

 

[Daydream believer]

In the first 2 seasons of owning my new Volvo MD2020 I had 5 go. No idea why. I now make sure that I buy them from the Volvo dealer, as some I have bought from non volvo suppliers do not actually fit properly & are suspect from the start. Since then I have only had 2 go whilst at sea in 5000 hours. Both in difficult situations.
I remove the impellor at the end of each season & then re fit it. First I check it for splits & can recall changing a few then, over the 18 years.

 

[Bandit]

I agree with Oldgit.

An impeller when the engine is stopped has a couple of blades distorted and that is where they sit for the winter unless removed.

If you change an impeller and it has no bits missing and no cracks it has done its job.

If there have been bits missing where are they , you need to go looking for them in the cooler stack a reasonable size job and your damaged impeller may have been allowing the engine to run too hot.

A new impeller is about £70 a serious overheat and a new engine cost is over a 1,000 times that cost. so odds of a 1,000 to one?

Check it fully or replace it annually, if you are removing it to inspect you may as well replace it.

 

[Montemar]

I replaced my impellers on TAMD41B’s a year ago. When I restarted a couple of weeks ago after a 4 month lift out a blade broke off the port impeller. Fortunately the EGT sensor I fitted went off. The bit is probably in the oil cooler so hopefully I can fish it out through the anode hole.
I replace them every year. First time this has happened and also first time boat had been lifted out over winter.
A visual check for water coming out of the exhaust would have revealed the problem but I was single handed and being lowered back in so no time to look.

 

[oldgit]

I replaced my impellers on TAMD41B’s a year ago. When I restarted a couple of weeks ago after a 4 month lift out a blade broke off the port impeller. Fortunately the EGT sensor I fitted went off. The bit is probably in the oil cooler so hopefully I can fish it out through the anode hole.
I replace them every year. First time this has happened and also first time boat had been lifted out over winter.
A visual check for water coming out of the exhaust would have revealed the problem but I was single handed and being lowered back in so no time to look.

The oil cooler is the first place any impeller blade will end up on the 40/41 . A single blade should not in theory cause a serious over heat, several might.
Depends how many are in there, did a previous owner have problem and not bother to discover where all the bits went.
Remove oil pipe.

Stick a mains hose pipe into the chamber and flush out any bits of blade in there.
A finger inserted into the oil cooler will usually detect any stuck bits, a piece of copper wire can dislodge these.
Removal and dismantling the oil cooler is pain.
Removing corroded screws and bolts when completely dismantling an old 40/41 oil cooler is done at your peril.
Leave well alone , it is possible to get the outer alloy casing welded/repaired but expensive and time consuming.

 

[madabouttheboat]

Many of the replies are based on personal experience with engines other than D6. From my experience D6, and for some reason only D6, impellers start to fail very quickly. Often after a year there will be bits of blades missing. If I owned a D6 I would be pulling the impeller every year and either replace, or be prepared to replace. They are not cheap so if it came out fine I would reuse it, but only for a maximum of 2 years.

 

[oldgit]

Many of the replies are based on personal experience with engines other than D6. From my experience D6, and for some reason only D6, impellers start to fail very quickly. Often after a year there will be bits of blades missing. If I owned a D6 I would be pulling the impeller every year and either replace, or be prepared to replace. They are not cheap so if it came out fine I would reuse it, but only for a maximum of 2 years.

New impeller £75 ?
Engine rebuild or worse ££££££

 

[Rappey]

My impellor is 41 yrs old. Its a jabsco. Spent 6 years on the hard. Im not changing it any time soon as its still in good condition
Others barely make a year ?
I took the pump apart last year. I did change the packing as the old was a little hard.
Its not a D6 engine but an impellor is an impellor ?

 

[kashurst]

My impellor is 41 yrs old. Its a jabsco. Spent 6 years on the hard. Im not changing it any time soon as its still in good condition
Others barely make a year ?
I took the pump apart last year. I did change the packing as the old was a little hard.
Its not a D6 engine but an impellor is an impellor ?

is it in a sailing boat?

 

[westernman]

My impellor is 41 yrs old. Its a jabsco. Spent 6 years on the hard. Im not changing it any time soon as its still in good condition
Others barely make a year ?
I took the pump apart last year. I did change the packing as the old was a little hard.
Its not a D6 engine but an impellor is an impellor ?

It seems that not all impellors are equal. Some after market impellors seem to be more brittle or go brittle quicker.

 

[ChromeDome]

I keep spare impellers on board and have Aqualarm flow alarms between strainers and engines.
In case of sea water shortage I get an alarm, way before an engine would be affected.

Never had an alarm in 11 years (apart from the selftest before starting), but replaced impellers after 7 years for the sake of good order. They came out as good as new, in all respects.