Weird impeller orientation (from factory)?

spoilsofwar · Feb 5, 2014

My boat has been winterized since September of 2012, due to me being deployed all of last year's NY boating season. I just moved down to SC, so I'm looking forward to getting out on Lake Murray within the next month or two. So, I've started doing some of my de-winterization tasks...

I decided to change the seawater pump impeller, even though the boat only has 21 hours on it, because its been two years and that seems to be the general recommendation to avoid a grenaded impeller. When I pulled the housing, I saw this:

I thought the orientation of the impeller vanes were all supposed to be pointing one way? Was this a factory screw up, or is it meaningless? Its been a while since I used the boat obviously, but it certainly never ran hot enough for me to take notice, though it could have been a bit higher then what people generally say the 4.3 GL's run at (~180 from what I've seen). I think it was usually at 190-200, but again, I couldn't swear to it.

As a side note, this was the fuel filter I pulled off the boat today. This is not the factory filter, but was one I installed when I winterized the boat at the end of 2012... No fuel was ever run through it; Its rusty and generally nasty inside! It will be changed of course, but just a heads up to anyone who has let theirs sit for a while... I think the mistake here was letting it sit dry.

Maclin · Feb 5, 2014

Re: Weird impeller orientation (from factory)?

Maybe the impeller had a chance to move from dead-center to off-center like that as it moved off the driven shaft, and the blades moved themselves into those positions before you could see them in their action poses. If there is a front cover and the impeller checked just before removal they may have been oriented correctly. I always pull mine out the front cover, so not sure exactly what can happen inside the housing if the housing with impeller is moved off the shaft.

spoilsofwar · Feb 5, 2014

Re: Weird impeller orientation (from factory)?

The off center part I understand; that's just the effect of the cam side of the housing pushing the impeller over without the shaft to hold it in the center. I suppose what you're saying is possible, but I don't think its likely... I pulled the housing and immediately turned it over and it was like that, I don't think that many vanes would have been able to "flip" their orientation so quickly, and so perfectly... I'm 99.9% sure they must have been like this all along.

There is no front cover on these volvo pumps, so no way to look at the impeller without pulling the housing.

lg260ss · Feb 5, 2014

Re: Weird impeller orientation (from factory)?

You probably turned it on the shaft a little while pulling it off, it wouldn't take much. The impeller has no choice but to correct itself once it is being spun by the shaft. Many times while replacing an impeller, one or 2 vanes will be pointing the wrong way while reinstalling. They correct themselves.

Be sure to use some dishwashing soap to install the new one. It will make it easier to get into the housing and lubricate it on start up.

skydiveD30571 · Feb 5, 2014

Re: Weird impeller orientation (from factory)?

Don S. always told me that vane direction didn't matter, and it would self-correct if it needed to. However I'm a perfectionist so I like for them to be sitting the correct direction. I rotate the impeller as I install it so that the vanes are resting correctly.

spoilsofwar · Feb 5, 2014

Re: Weird impeller orientation (from factory)?

I did have to twist the housing back and forth a bit to get it to slide off the shaft... That must have been enough to do it. Thanks guys

Tail_Gunner · Feb 5, 2014

Re: Weird impeller orientation (from factory)?

Only possilbe explanation is that vane popped backwards after you dismounted the water pump....Trust me it did not dun that way when mounted...Odd enough though make sure that is the right impeller for that housing..it could be undersized that would allow it spring loose like that.

Fun Times · Feb 5, 2014