Surprised at the condition of impeller 234 hrs D3

[BB marine]

I replaced the impeller for the D3 220 hp Volvo today. This was routine replacement 234 hrs on the engine Two seasons of use. All fresh water, no groundings. I didn't expect to find any issues with the impeller. When I removed it I was surprised to see 2 vanes damaged almost 180 degrees apart. The rest of the impeller looked like I would expect slight set with minimal wear.The pump housing looked good no scoring. The face plate of the bearing housing portion of the pump had some wear at the narrow part of the eccentric. Other then that it looked good. I have seen impellers destroyed from dry rot and old age or being run dry . I have seen impellers loose efficiency because they have a bad set to them. This one has me puzzled, not much of a set, no dry rot cracks, the vanes are very pliable, not much wear, but 2 damaged vanes.




the damage is 180 degrees apart

 

[Newf]

From the photos it looks like pieces were torn out,,sharp looking edges,,so you may have suck in a chip of wood or hard plastic etc into the pump.. The left side vane in both cases of the top two pics appear to have a convex dip in the centre and at the two outer edges of the vane. Is this just how it looks from the photo or is that how they actually are? Not familiar with your engine but was thinking that they should be straight across. Not the same impeller in my D1-30 but I've replaced four ( at 350 to 400hr each) and all have had cracks at the root of the vanes but no damage to the outer lip.

 

[MikeK]

From the end view it appears that some blades have opposite set. Probably not install correctly.

 

[NorthernFocus]

From the end view it appears that some blades have opposite set. Probably not install correctly.

This is a common misconception. It doesn't matter if you install the impeller with the vanes angled completely opposite of direction of rotation. As soon as the engine runs they will flop back over the opposite way. It is very common to find the vanes askew when the plate is removed from the pump. This is due to the fact that diesel engines often counter rotate slightly when they are shut down.

What is telling is the fact that the vanes have taken a set at all. This is indicative of the fact that the rubber is aged and is losing its flexibility. Which is also likely why the two vanes failed. Simply age related fatigue failure. "Age" in the life of the material doesn't necessarily mean only chronological time nor hours of engine operation. It is more a function of total exposure of the material over its life. Cumulative cycles/rotations, operating temperature, chemical exposure, etc, all cause "aging" of elastomers.

Brian, in the photos the impeller looks as if it has been painted. Or is that something else that's just coming through that way in the pics? In any case due to the above mentioned stiffness of the material it's good that you changed it out. That impeller looks to have been reaching end of useful life.

 

[BB marine]

From the end view it appears that some blades have opposite set. Probably not install correctly.

This is a common misconception. It doesn't matter if you install the impeller with the vanes angled completely opposite of direction of rotation. As soon as the engine runs they will flop back over the opposite way. It is very common to find the vanes askew when the plate is removed from the pump. This is due to the fact that diesel engines often counter rotate slightly when they are shut down.

What is telling is the fact that the vanes have taken a set at all. This is indicative of the fact that the rubber is aged and is losing its flexibility. Which is also likely why the two vanes failed. Simply age related fatigue failure. "Age" in the life of the material doesn't necessarily mean only chronological time nor hours of engine operation. It is more a function of total exposure of the material over its life. Cumulative cycles/rotations, operating temperature, chemical exposure, etc, all cause "aging" of elastomers.

Brian, in the photos the impeller looks as if it has been painted. Or is that something else that's just coming through that way in the pics? In any case due to the above mentioned stiffness of the material it's good that you changed it out. That impeller looks to have been reaching end of useful life.

Dan
I agree with all stated here. I still question the damage. Right now looking at the impeller other then the damage to the 2 vanes it looks new. All vanes are straight out showing no set. The pictures shown were taken shortly after removal.The vane flexibility is equivalent to the new replacement. This engine was manufactured in 2015, installed 2015 by Cutwater commissioned by the dealer in early march 2016. Not an old impeller. It is also a newer style pump assembly so my assumption is the pump was not on the shelve for years before being installed on the engine.The coating that you see is possibly glycerine which is applied to the impeller and housing for assembly. At this point I'm going to replace the impeller at the end of next season and inspect it. I have removed and replaced many impellers in the past and normally the reason for damage is evident. Looking at the impeller this morning it looks like a new impeller, same dexterity of a new impeller, very little to no evident wear to the ends of the impeller. I guess I'll go with preventative maintenance saved a boating day!!!

From the photos it looks like pieces were torn out,,sharp looking edges,,so you may have suck in a chip of wood or hard plastic etc into the pump.. The left side vane in both cases of the top two pics appear to have a convex dip in the centre and at the two outer edges of the vane. Is this just how it looks from the photo or is that how they actually are? Not familiar with your engine but was thinking that they should be straight across. Not the same impeller in my D1-30 but I've replaced four ( at 350 to 400hr each) and all have had cracks at the root of the vanes but no damage to the outer lip.

I thought about what you have stated but 2 things that don't add up . 1) the object would have to pass through the reverse gear cooler.(possible but not probable) 2) the inlet and outlet of the pump is in the center of the pump housing. The damage is not in the center of the impeller.

 

[knotflying]

More importantly, where did the pieces go? Are they still in the heat exchanger or do you think they passed through?

 

[BB marine]

More importantly, where did the pieces go? Are they still in the heat exchanger or do you think they passed through?

I thought about that. First they would have to pass thru the after cooler then to heat exchanger. There are three pieces that broke off. Each piece that broke off is probably close to the diameter of a tube.It could possibly pass thru to the exchanger.and then possibly pass thru the exchanger and out the exhaust. I'm not that lucky so I would say the pieces are still in there somewhere. I'm not at this point going to go look for them. In general a exchanger can have 10% of the tubes plugged and maintain efficiency. The pieces missing would not be close to causing 10%. I also had no coolant temperature issues at all normal cruising to 3200 rpm 180 degrees, 3600 rpm 185 degrees, WOT climbed to 190 degrees. These temps are recorded my last run of last season before pulling the boat for storage. I assume this was with 2 damaged vanes and 3 pieces of rubber somewhere in the cooling system. So yes, good question Mike. I wish I had them in my hand but at this point I'm not going to worry about it. I'm going to have a friend of mine ( Volvo Tech) take a look at the impeller and get his opinion.

 

[TexasEye]

Any idea on cure date?

5 years is a good number for the trash can...

These Impellers work hard and suck up some nasty stuff.

Plus cold weather is probably a life limiter.

I plan on a one year Limited Life...

(PS: I'm new)

 

[NorthernFocus]

...Right now looking at the impeller other then the damage to the 2 vanes it looks new. All vanes are straight out showing no set. The pictures shown were taken shortly after removal.The vane flexibility is equivalent to the new replacement...

Then you've got a bonafide mystery. And one not likely to ever be solved. I've simplified life by making the impeller replacement part of spring commissioning. It's a real PITA to replace on my boat/engine. But that is why I do it in my particular situation. It would be even more of a PITA if it had to be done in a seaway with a steep, rocky shore under the lee.

 

[BB marine]

Any idea on cure date?

5 years is a good number for the trash can...

These Impellers work hard and suck up some nasty stuff.

Plus cold weather is probably a life limiter.

I plan on a one year Limited Life...

(PS: I'm new)

Cure date ??? I have no idea! Hell the one I replaced it with is most likely older then the one I took out! We have owned the boat for 2 years (New) used the boat a total of 6 months, and put 234 hours on it. I'm changing the impeller when I change the oil, 100 hrs. I've made alterations to the step going to cave. Its an easy 20 minute job to replace. Maybe quicker the next time. Yesterday was my first time doing it.

Then you've got a bonafide mystery. And one not likely to ever be solved.

[/quote]

I've worked with to many engineers :" there is a root cause for for every failure, please provide a root cause analysis". I would like to see the expression on an engineers face if I said "Its a bonafide Mystery" I like that!! :shock:

I know its just a boat. I thought I would post a few pics for discussion. Thanks for responses.

 

[NorthernFocus]

...I've worked with to many engineers :" there is a root cause for for every failure, please provide a root cause analysis". I would like to see the expression on an engineers face if I said "Its a bonafide Mystery" I like that!! :shock: ...

Yes that would go under "other" on the form.🙂

 

[Red Raven]

The only other thought I have is that it was damaged/stressed on install (or a bad part) and that eventually led to the vane failures. I have replaced mine (D3-200) three times now (annually) and have never seen any damage or significant wear. It can be a PITA to get the new impeller in place when working from that tight position. It is possible to damage it by forcing it in. Can’t imagine the factory would have this same difficulty though.

 

[baz]

I would imagine running the impeller 'dry' for just a short time can place a lot of heat/stress/friction on one or more of the vanes which would compromise their integrity leading to a shorter life and possible breakage.

Had the boat been on the dry for any extended time resulting in the impeller housing drying out ?

 

[BB marine]

I would imagine running the impeller 'dry' for just a short time can place a lot of heat/stress/friction on one or more of the vanes which would compromise their integrity leading to a shorter life and possible breakage.

Had the boat been on the dry for any extended time resulting in the impeller housing drying out ?

I agree running it dry could cause damage. Normally there is evidence of a dry run to all vanes. it is possible though. As far as winter storage and the boat sitting. Yes it does but it is stored in a heated building. I don't drain anything. Yesterday when I removed the impeller the pump housing and water line coming from the cooler was full of water and drained when I pulled pump bearing housing off to remove impeller. I'm sure the impeller gets a set from sitting. That's what we do in the midwest.

 

[baz]

Brian: It's not just having the boat on the dry that could cause harm to the impeller but when and if at any time there's an event that causes a water blockage that restricts or even stops water from getting to the impeller housing for a short period.

I'm told that with as little as a 10 second period without water in the impeller housing the impeller can be compromised.

Then there's the water condition such as boating close to sandy bottom and for the raw water ingestion to suck in sand particles that easily flow through the strainer and on into the impeller housing causing impeller damage etc.

The fact that two of the impeller vanes have obvious stress and fracture when the others have not, leads me to think it's not a material defect but that some object has entered the impeller housing causing the vane damage.

From what I know about impeller failures, the main indication is for the vane(s) to crack/split/fail at their base(s) which presumably is the point of greatest stress as the impeller rotates.

I've know people who have replaced their impellers with brand new ones and have them fail within hours of being used.

If the impeller can be accessed easily it should be checked frequently IMO.

On my 2016 R-21EC my impeller housing was in full view and checking the impeller could be dome within a 2 minute window. I did install the SpeedSeal product that really simplified the impeller inspection task, and well worth the money IMO.

 

[TexasEye]

I replaced the impeller for the D3 220 hp Volvo today. This was routine replacement 234 hrs on the engine Two seasons of use. All fresh water, no groundings. I didn't expect to find any issues with the impeller. When I removed it I was surprised to see 2 vanes damaged almost 180 degrees apart. The rest of the impeller looked like I would expect slight set with minimal wear.The pump housing looked good no scoring. The face plate of the bearing housing portion of the pump had some wear at the narrow part of the eccentric. Other then that it looked good. I have seen impellers destroyed from dry rot and old age or being run dry . I have seen impellers loose efficiency because they have a bad set to them. This one has me puzzled, not much of a set, no dry rot cracks, the vanes are very pliable, not much wear, but 2 damaged vanes.




the damage is 180 degrees apart

What about "Kick Back" during start or shut down? During shut down if the kill switch is released before the engine completely stops it could run backwards momentarily or even until killed...You'd have no oil or water circulation during the event...Looks like this impeller turned backwards at some time...A Professional analysis...

 

[TexasEye]

What about "Kick Back" during start or shut down? During shut down if the kill switch is released before the engine completely stops it could run backwards momentarily or even until killed...You'd have no oil or water circulation during the event...Looks like this impeller turned backwards at some time...A Professional analysis...

 

[Cutwater28GG]

This is the reason why I get my impeller changed on every annual service. It’s too big of an item to fail on a single engine boat and resulting damage can be expensive.

Perhaps Rubber age and temperature swings throughout the year may also be a factor?

 

[rocklobster]

Anyone ever try these impellers. I think the coast guard uses them.

https://www.gcsmarine.com/content/impellers/impellers

This is the reason why I get my impeller changed on every annual service. It’s too big of an item to fail on a single engine boat and resulting damage can be expensive.

Perhaps Rubber age and temperature swings throughout the year may also be a factor?

Sent from my iPhone using Tapatalk

 

[NorthernFocus]

What about "Kick Back" during start or shut down? During shut down if the kill switch is released before the engine completely stops it could run backwards momentarily or even until killed...You'd have no oil or water circulation during the event...Looks like this impeller turned backwards at some time...A Professional analysis...

Pretty sure the common rail EFI engines won't run backwards. They can kick back a partial rotation but that's about it. The controls on the Cummins also have reverse rotation protection in case the starter is wired backwards.

Anyone ever try these impellers. I think the coast guard uses them.

https://www.gcsmarine.com/content/impellers/impellers

Some people swear by the Globe impellers and they look promising. Not recommended for those with Cummins engines. The clearances on the bore/keyway are so tight on the impeller that it's not feasible to install the impeller without whittling on either the key or the impeller or removing the pump. Been there, done that.