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M5/M6 Impeller Failures

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Eagleboy99
1 hour ago, tjklein said:

Look at the new motors and see how much water has to be drawn before it gets to the impeller housing. 

How is it that the "old" motors have no issues whatsoever?

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asnowman

I have been paying attention and reading along on this one. We are now at 90 hours on our 2019 with M6, no issues with the engine thus far, but i do have a spare impeller handy now, just in case, seems like very cheap insurance to keep us on the water.

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tjklein

It makes sense when you look at both designs, but it's not obvious and it's not always going to cause it to fail. Over time it will cause premature failure.

It apparently made it by engineers so it's tricky...just like every recall issue.  

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gregtay
22 minutes ago, tjklein said:

It makes sense when you look at both designs, but it's not obvious and it's not always going to cause it to fail. Over time it will cause premature failure.

It apparently made it by engineers so it's tricky...just like every recall issue.  

I think there is more to it then just the location of the pump.  I am sure they tested the snot out of their design and it was fine how they signed off to ship it. Something changed (either the impeller quality changed, the factory floor changed how it the cooling system is installed, etc.  I believe they did move the location of the fresh water intake on some models because the old location had some clearance issues with the location of the thruster mounting bolts. In the end I think the current issue is more prevalent in 2020 boats.  It seems like most of the 2019 boats are less effected by the latest issue.  Yes, 2019 had theri own impeller issues from Jan-March of 2019.. they changed to a new impeller design and that seems to have fixed it.  I am sort of wondering if after the 2019 issue the engineering team made a change to the cooling setup thinking they were improving water flow, etc but in the real world the opposite happened.  I also heard at one point Malibu dropped the fresh water flush kit because it was causing cooling system issues (maybe thinking it was contributing to nuked impellers... but it looks like the flush kit is orderable again so clearly not a long term issue.  I have an April '19 build M6 and I have the flush kit.  My boat came with the new/redesigned impeller. So far... no issues.  And again I want to stress.. I have zero factual information, just giving my theories base on what I have seen   I think the issue will be fully solved without moving the water pump, I don't think under normal conditions (meaning the original design specs) the pump has any issue priming.

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Slayer
8 hours ago, IXFE said:

Here's what I know...

First, as evidence by this very forum, not all M5/M6 boats are overheating.  But for those that are... 

There are a couple of separate overheat issues that are all being blamed on impellers which in fact are actually separate items with same overheat end result.

  1. Last week, Malibu released a Service Bulletin to your dealers that will solve aprox. 35% of those boats that are experienced overheating.  This one has nothing to do with the water pump or the impellers. It includes a recalibration of the ECM to include performance enhancements as well as improved temp regulation on the outlet side of the motor.  The service bulletin also calls for a replacement of a spring in the Y-pipe coolant relief valve, as the supplier did not use stainless material, as spec'd by Malibu.  
  2. The other 65% of those who overheat will be solved by a future solution that relates to the water pump but the supply chain has them backed up due to covid. Malibu received bad impellers that were not to spec but was not aware until they started failing. You may not know this, but Malibu does not install impellers at the factory; they come pre-assembled in the pumps.

In summary, Malibu is aware and is diligently working on solution. In fact, the solution is at hand, but held back by global supply chain issues (like so much else we all are dealing with in this crazy new world).

I hope this helps...

Thanks for the intel!!  Much appreciated.  

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COOP
Posted (edited)
12 hours ago, tjklein said:

 

There is a fix in the works. Malibu will be installing something like a check valve from my understanding in future boats. Very, very basic explanation, but essentially without RPMs (idling right away after starting) you're not getting water to the impeller and priming it. This is burning them out prematurely.

Look at the new motors and see how much water has to be drawn before it gets to the impeller housing. 

The check valve addresses manifold overheat issues. Not related to the impeller.

Edited by COOP

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COOP
Posted (edited)
12 hours ago, Eagleboy99 said:

How is it that the "old" motors have no issues whatsoever?

The impeller housing is low on the old motors.. the new pump housing is on top of the motor. Its a pretty long draw, and because of this the impeller is dry every time you start the boat.

Edited by COOP

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Slayer
7 minutes ago, COOP said:

The impeller housing is low on the old motors.. the new pump housing is on top of the motor. Its a pretty long draw, and because of this the impeller is dry every time you start the boat.

Question for you.......

Based on the pump location and your experience with these engines, what's the solution?  A quick throttle bump, or a different "run dry" type impeller, or something else?

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COOP
2 hours ago, Slayer said:

Question for you.......

Based on the pump location and your experience with these engines, what's the solution?  A quick throttle bump, or a different "run dry" type impeller, or something else?

We've been looking at the run dry impellers. I think given the location of the pump these will be the best option currently. I think the Globe number is 626. But Ive not had luck finding any in stock stateside. 

Long term Im not sure what the solution is, check valve, loop in the hose to keep water at the pump? I am curious to see what Malibus solution will be. 

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gregtay
11 hours ago, IXFE said:

Here's what I know...

First, as evidence by this very forum, not all M5/M6 boats are overheating.  But for those that are... 

There are a couple of separate overheat issues that are all being blamed on impellers which in fact are actually separate items with same overheat end result.

  1. Last week, Malibu released a Service Bulletin to your dealers that will solve aprox. 35% of those boats that are experienced overheating.  This one has nothing to do with the water pump or the impellers. It includes a recalibration of the ECM to include performance enhancements as well as improved temp regulation on the outlet side of the motor.  The service bulletin also calls for a replacement of a spring in the Y-pipe coolant relief valve, as the supplier did not use stainless material, as spec'd by Malibu.  
  2. The other 65% of those who overheat will be solved by a future solution that relates to the water pump but the supply chain has them backed up due to covid. Malibu received bad impellers that were not to spec but was not aware until they started failing. You may not know this, but Malibu does not install impellers at the factory; they come pre-assembled in the pumps.

In summary, Malibu is aware and is diligently working on solution. In fact, the solution is at hand, but held back by global supply chain issues (like so much else we all are dealing with in this crazy new world).

I hope this helps...

Thanks IXFE.. I think that helps a ton.  And sort of my point is... why didn't Malibu have a customer service rep come on to TMC and post something along those lines to just give people some information and shut down the negativity and rumors.  I think most people are understanding with answer like "supply chain issues" or even "we know some boats are having issues and our top engineers are working on a solution and we won't roll it out to everyone till we are 100% confidant in the solution."  

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Slayer
13 minutes ago, COOP said:

We've been looking at the run dry impellers. I think given the location of the pump these will be the best option currently. I think the Globe number is 626. But Ive not had luck finding any in stock stateside. 

Long term Im not sure what the solution is, check valve, loop in the hose to keep water at the pump? I am curious to see what Malibus solution will be. 

I too am interested in what their solution is.  I've run Globe in my RLXi and have experienced prime issues, but that's easily managed with a bump in the throttle on start up.  I like your thinking with the check valve and loop.  It seems like a very simple, cost effective solution.  I'm surprised by the amount of head required to pull water up to the M5/M6 impeller location.  It seems that there was something missed in locating it where they did without keeping it wet.  

 

Thanks for the response.  I appreciate it. 

 

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oldjeep
Just now, 23LSVOwner said:

 

I know of companies that participated on forums, etc in the past and they quickly regretted as it turned into a total CF.

I'd agree, although Larry from Indmar (EngineNut)  was a great resource on this board when he used to show up and answer questions.  Don't recall anyone ever getting on him.

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gregtay
30 minutes ago, 23LSVOwner said:

 

I know of companies that participated on forums, etc in the past and they quickly regretted as it turned into a total CF.

I agree that normal participation is likely not a rabbit hole they would want to go down. But in the past I believe Malibu has at least reached out to the TMC mods and given them info to post, etc.

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tjklein
1 hour ago, COOP said:

We've been looking at the run dry impellers. I think given the location of the pump these will be the best option currently. I think the Globe number is 626. But Ive not had luck finding any in stock stateside. 

Long term Im not sure what the solution is, check valve, loop in the hose to keep water at the pump? I am curious to see what Malibus solution will be. 

 

This is what I was told. We'll see what the final answer is. I'm sure they're testing and putting hours on something as we speak.  IXFE seemed to be on the right track as well.

 

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G Spot
Posted (edited)
14 hours ago, gregtay said:

I think there is more to it then just the location of the pump.  I am sure they tested the snot out of their design and it was fine how they signed off to ship it. Something changed (either the impeller quality changed, the factory floor changed how it the cooling system is installed, etc.  I believe they did move the location of the fresh water intake on some models because the old location had some clearance issues with the location of the thruster mounting bolts. In the end I think the current issue is more prevalent in 2020 boats.  It seems like most of the 2019 boats are less effected by the latest issue.  Yes, 2019 had theri own impeller issues from Jan-March of 2019.. they changed to a new impeller design and that seems to have fixed it.  I am sort of wondering if after the 2019 issue the engineering team made a change to the cooling setup thinking they were improving water flow, etc but in the real world the opposite happened.  I also heard at one point Malibu dropped the fresh water flush kit because it was causing cooling system issues (maybe thinking it was contributing to nuked impellers... but it looks like the flush kit is orderable again so clearly not a long term issue.  I have an April '19 build M6 and I have the flush kit.  My boat came with the new/redesigned impeller. So far... no issues.  And again I want to stress.. I have zero factual information, just giving my theories base on what I have seen   I think the issue will be fully solved without moving the water pump, I don't think under normal conditions (meaning the original design specs) the pump has any issue priming.

I agree with you that I don't believe the pump location is the issue, based on my small sample size of two M6 motors / 4 impellers now FWIW.

My 2019 M6 went all season 125 hours and that impeller looked as good as new when I changed it proactively for the next owner. It had markings of 15000A.

My 2020 M6 blew at 54 hours. Yes, I had a spare and was able to fix on the lake in the middle of a vacation, so no big deal. The factory impeller had no markings.

My strainer never has any material debris in it. And my boat usage is very consistent across both years.

I've also found that I still have water in the impeller housing after it being on the lift or trailer for a week between uses (in Texas heat), so I'm not convinced it's actually running dry.

I suspect this is more of an issue with defective impellers. Perhaps tolerances inside the housing have changed, which could also cause premature wear on the impeller. Additionally, I was surprised how sharp some of the leading edges are inside of the housing, which seems less than ideal.

Edited by G Spot

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eubanks
On 8/17/2020 at 12:22 PM, tjklein said:

 

This is what I was told. We'll see what the final answer is. I'm sure they're testing and putting hours on something as we speak.  IXFE seemed to be on the right track as well.

 

No tweaking to the water housing or it’s location is going to be made. Per Malibu, the issue was concluded to be with the impellers themselves. That goes for an impeller I had just installed by my dealer a month ago that fried after less than 10 hours on it. 

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COOP
1 hour ago, eubanks said:

No tweaking to the water housing or it’s location is going to be made. Per Malibu, the issue was concluded to be with the impellers themselves. That goes for an impeller I had just installed by my dealer a month ago that fried after less than 10 hours on it. 

Interesting. Not the same info I have.

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Murphy8166
11 minutes ago, COOP said:

Interesting. Not the same info I have.

Same - not the same info I have either. 

 

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agarabaghi

posted this in the maintenance forum but might be more visible here:

I think this list will be super helpful for those who are looking to buy replacements:

Here are all the options I have found with my experience:

Sherwood 15000k - Only failure I have had was with a OEM impeller replaced at dealer (bad stock?)

https://www.bakesonline.com/impeller-service-kit-sherwood-15000k-neoprene-impeller.html

Bakes marine V2 version - No experience

https://www.bakesonline.com/malibu-m5-and-m6-engine-water-pump-impeller-kit.html

Globe 626 - Advertised as run dry, used a different kind of rubber than other 2

https://marinepartssource.com/impeller-blue-keyway-12-blade-globe-626

JMP Wax Infused 7352-01k - One of the few brands that does not use off the shelf rubber mix, they make their own composite with WAX infusion. Will be running this next.

https://bigblueoceanmarine.com/7352-01k-jmp-marine-flexible-impeller-kit-replaces-jabsco-18327-0001-sherwood-15000-15000k-cummins-3916720-mercruiser-47-853126/

StayCoolPump 15000k replacement - Regular replacement impeller, i have this currently in my m5 with 40hours no issues.

https://www.staycoolpumps.com/store/p54/Impeller_Kit_Replaces_Sherwood_15000K_Jabsco_18327-0001-P.html

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IXFE
16 hours ago, COOP said:

Interesting. Not the same info I have.

 

16 hours ago, Murphy8166 said:

Same - not the same info I have either. 

 

Same here... go back and read closely what I posted (specific the 2nd item). Suggests a change would already be here if not for the supply chain. 

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agarabaghi

So as mentioned, im switching impellers every 50 hours. 

1st was whatever came with the boat upon delivery (early 2020) got the boat in Oct 2019.

2nd was replaced by dealer and failed almost immediately

3rd one is the one pictures below, Staycoolpump brand from Amazon for the sherwood 15000 and last 50hours and showed very little signs of wear. It actually looks much better than my PCM impellers which i would change every 50hours as well. 

4th impeller going in now at is the JMP impeller. 

I remove the entire housing as it takes 10mins (timed) to remove it, and then you can install the new impeller inside in the AC. 

As mentioned in the other post 2x 15mm wrenches , 1 1/2" drive breaker bar, 5/16 socket or flat head.

- Remove the hose going to the heat exchange and housing

- remove the intake house from strainer 

-losen the 2 15mm nuts on the houing

- release the belt on from the housing using the 1/2 dive on the tensioner

- remove the nuts, and remove the casing.

MxPUzAxl.jpg

Wrenches and tensioner

ZBKFfPhl.jpg

Housing removed

X7d4oH8l.jpg

Old impeller, as you can see it still has water in it and there was water in the houses, so not sure the priming theory is right.

thNgE5Wl.jpg

Old impeller, everything looks totally fine.

 

To me, and i have nothing to back this up by my own experiences and friends experiences, unless the casting of the housing changed sometimes mid 2020 and is slightly out of spec the issue is with the impellers. I have had 1 completely fall apart and 2 others which have been fine, going on my 3rd. If it was the housing i feel like all of them would have failed at similar time. I dont think i know anyone who has had a 2nd failure either but i could be mistaken. 

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Jayp13

For all the do it yourselfers out there. Thought this was a helpful video (if for nothing more then to understand where everything is located)  

 

 

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