Impeller blades backwards

[OrangeCrush]

Hello,

Yesterday I opened up my impeller housing (Yanmar 4JH5E) to replace the impeller. The boat is new to me and it's the first time I've had it open, although it was pumping water well and running fine in the fall.

I was surprised to find that not all of the impeller blades were facing the same direction. Two of the blades were clearly folded in the opposite direction from the rest. This happened where the blades are squeezed tighter by the housing's irregular shape. Even some of the blades where there is more space were oriented backwards as well. (See pic, apologies that it is blurry)

The only explanation that I can think of is that maybe I turned the driveshaft pulley the wrong way slightly when I was taking off the alternator belts (?).

I'm definitely replacing the impeller and I will make sure to get the orientation right relative to the direction of rotation. But can anyone explain how it got like this? Is there anything else wrong here that a new impeller won't fix?

[sailah]

That's normal mine always looks like that.

Coat up the new impeller with the special lube they send with it so it won't have a dry start.

I replace my impeller every year. I keep the ones that come out intact as spares along with new paper gaskets in case I have an issue. About 50% of the time the impeller has a blade missing in the fall when I remove it for winterization. It's always found in the heat exchanger.

[Cheechako]

You may have turned it. When your engine does it's last stroke shutting down, some make a slight turn backwards. I wouldn't worry about it.

[OrangeCrush]

Originally Posted by sailah

That's normal mine always looks like that.

Good to know... Do you actually install it like this or does it just end up like this after the season? I presume you still try to install it with the blades facing the right direction.

My impeller wasn't missing any blades but there were a number of small plastic shards in my raw water strainer. Not sure where it came from but I will check the heat exchanger for additional debris.

[sailah]

Originally Posted by OrangeCrush

Good to know... Do you actually install it like this or does it just end up like this after the season? I presume you still try to install it with the blades facing the right direction.

My impeller wasn't missing any blades but there were a number of small plastic shards in my raw water strainer. Not sure where it came from but I will check the heat exchanger for additional debris.

I shove mine in there any way it'll fit I liberally coat in the lube and clock in the pump direction to get it started. After that I go by feel to ensure the drive pin is in the shaft groove. Push it in there, the pump shaft will correct anything once it spins up. Also make sure the cover is clean where it mates with the pump housing. I usually hit mine on my Scotchbrite wheel to remove any remaining gasket or burrs.

Seriously I don't know why the blades invert like that but every time I've taken a pump cover off mine looks like that and mine's not a Yanmar either. Same goes when I was working on much larger boats (150') gensets etc.

Maybe it has something to do with the blades going from high to low pressure?

[30West]

Originally Posted by sailah

Also make sure the cover is clean where it mates with the pump housing. I usually hit mine on my Scotchbrite wheel to remove any remaining gasket or burrs.

A Scotchbrite wheel can take out too much material, create gaps and leaks at the seal. Better to use a flat file held flat on the surface, drag it around slowly looking for resistance to find high spots or leftover gasket.

Lube your impeller, O-rings, and hoses with dielectric grease, it is made for preserving and lubricating rubber parts. Cheap at auto parts stores.

[a64pilot]

Originally Posted by Cheechako

You may have turned it. When your engine does it's last stroke shutting down, some make a slight turn backwards. I wouldn't worry about it.

This, they often turn backwards at shutdown about a quarter a turn, watch.
I put a zip tie on the blades with them all folded in the correct direction, the zip tie keeps them folded and makes installation easy.
I have never seen a special lube, I just use a little liquid dish soap.
Do not use silicone grease, it may deteriorate the impeller and does not dissolve in water, you want something that dissolves

[OrangeCrush]

Originally Posted by sailah

After that I go by feel to ensure the drive pin is in the shaft groove.

Sailah can you elaborate on this? You mean making sure the splines on the inside of the impeller are lined up with the shaft? I feel like you wouldn't be able to get it in if it wasn't already lined up.

Yeah I had some silicone grease ready for the job but the impeller instructions said to use glycerine so I picked up some of that to use instead. The zip-tie trick sounds like it could be helpful as well. Thanks for the help, all.

[LLizzard]

I put a zip tie on the blades with them all folded in the correct direction, the zip tie keeps them folded and makes installation easy.

A hose clamp and cordless screwdriver works well to compress vanes on beefier impellers from larger engines.

[Darby695]

Originally Posted by LLizzard

I put a zip tie on the blades with them all folded in the correct direction, the zip tie keeps them folded and makes installation easy.

A hose clamp and cordless screwdriver works well to compress vanes on beefier impellers from larger engines.

Talking of impellers !
Has anyone got any experience with this rather ingenious modification?
. This appears to be good value when you consider the increase in life of the impeller, as well as the ease of changing the impeller, if it's needed to be done quickly..
It seems it would be very easy to check condition etc
Thoughts?
[url]http://www.speedseal.com/SpeedsealLife/Lifehowitworks.htm

[sailah]

Originally Posted by OrangeCrush

Sailah can you elaborate on this? You mean making sure the splines on the inside of the impeller are lined up with the shaft? I feel like you wouldn't be able to get it in if it wasn't already lined up.

Yeah I had some silicone grease ready for the job but the impeller instructions said to use glycerine so I picked up some of that to use instead. The zip-tie trick sounds like it could be helpful as well. Thanks for the help, all.

Our pumps may be a little different. I don't have splines on my impeller. I just have a single stainless pin across. This matches a slot in my pump shaft. So it can go in at a certain angle, and 180 degrees from that same angle. So I shove it in a tiny bit to get the blades started, then clock it until I feel the pin seat in the slot, then push it all the way in.

My boat has a V drive transmission so my pump is facing aft and a complete contortion act to get at. Which is why I do it by feel since it's impossible to see the pump and you hands at the same time.

It looks like you have simple and easy access, I'm jealous.

I like the zip tie trick as well as hose clamps, will file that away thanks

[sailah]

Originally Posted by 30West

A Scotchbrite wheel can take out too much material, create gaps and leaks at the seal. Better to use a flat file held flat on the surface, drag it around slowly looking for resistance to find high spots or leftover gasket.

Lube your impeller, O-rings, and hoses with dielectric grease, it is made for preserving and lubricating rubber parts. Cheap at auto parts stores.

I would respectfully disagree about the scotchbrite wheel. In the wrong hands anyone can ruin something with a power tool. I find my 12" Extra Fine wheel on a 3HP Baldor pedestal buffer to be almost a precision instrument. A file won't remove the gasket whereas the wheel will and leave nothing but a shiny surface. I usually follow that up with a couple rubs on my surface plate with some 320 sandpaper. Never had a leak been doing it that way for years. My extrafine wheel won't really remove the parent material unless you leaned into it. At which point it would be way to hot to hold. It really is the perfect tool for the job in my humble opinion.

[OrangeCrush]

Ah ok that makes sense, thanks for the explanation. Yes mine is luckily quite easy to get to. There isn't any gasket stuck to my surface plate, I think I will be fine simply cleaning it with soap and water before putting it back on.

[Jim Cate]

Originally Posted by a64pilot

This, they often turn backwards at shutdown about a quarter a turn, watch.
I put a zip tie on the blades with them all folded in the correct direction, the zip tie keeps them folded and makes installation easy.
I have never seen a special lube, I just use a little liquid dish soap.
Do not use silicone grease, it may deteriorate the impeller and does not dissolve in water, you want something that dissolves

A64,I've been under the impression that silicone grease was not harmful to rubber products, and that petroleum based greases were. Silicone grease is often recommended for lubing o-rings, and i have used it thus for many years besides using it on water pump impellers. NEver found identifiable harm from this practice.

Further, why do you want the lubricant to dissolve? What harm will it do to the impeller as it runs? It will wear off pretty quickly at any rate, i suspect.

Jim

[Calif.Ted]

Decades ago I bought a little plastic tub of what was labeled "Impellor Lube" from the auto/boat part store near the harbor, cost $10 and so far appears to be a lifetime supply, I may leave it to my mechanic in my will. For as long as I can remember both Johnson and Jabsco replacement impellors have come with a little pack of lube.
http://www.marinepartssource.com/new...bricant Grease