Surprised at the condition of impeller 234 hrs D3

[Brian B]

I just replaced the impeller on my MASE generator with a Globe Run Dry Impeller. The installation went well until I tried to install the new O-Ring that is supplied, it was too large so I had to use the old one to complete the installation. I sent the company an email explaining my experience and within a couple of hours I had a response asking for my complete address and they would send me a new one.
On my Yanmar 4BY2 150 I change the impeller yearly regardless of hours or what the manual suggests. The old one always looks as good as the new one I install.

 

[BB marine]

I talked to a couple Volvo techs today and showed them my impeller. Both agreed that it was not a dry run and that beside the three cuts in the vanes the impeller was in good shape. Their theory is the vanes were cut by the narrow "ramp between either the intake or discharge ports of the pump. Most likely happen early on and I've been running with it this way. They both have seen it happen to impellers used on Onan generators which is the same pump.( Most of the engines they work on are D8 and D11 although they just inventoried a 2018 Jeanneau NC 33 twin D3) The edges of the ports and the "ramp" sometimes have sharp edges when new from machining, there is not enough chamfer and it cuts the impeller, after it gets cut, part of the vane gets caught in the port and tears. Usually after the impeller runs in the housing for a while it wears or smoothens the edge of the "ramp" and port. The "ramp" or divider on smaller pumps like this is narrow. When looking at the pictures I posted it is visible right in the center of the impeller small imprint of the "ramp" or divider. Their take on it was its not very common but it happens. They advised me to inspect the impeller mid season to see if it happened again. If it does I should get a new pump housing. They both said the fact that it has 234 hours on the impeller it probably won't happen again. Just another opinion. At this point I'm going with Dan opinion its a" Bonafide Mystery" a damaged impeller that needed to be replaced. Thanks all for your opinions.

 

[NorthernFocus]

That's a good theory but the fact that only two vanes were damaged still makes it a mystery. There's some little lady that assembles pumps giggling about how puzzled people must be when they change their first impeller and find the chunks missing out of the vanes where she nipped them with her pliers. Volvo probably has a team of engineers and materials experts that have been doing a root cause analysis for the past five years trying to figure out why two vanes 180 degrees apart always fail in the first few hours of operation. "Ya dees ees a bonafide meestery vor shore" 😀