Yan Impellor replacement

[Capt Morgan]

I am about to replace the raw water pump impeller on my Yanmar 4JH4E engine. The prior owner of this boat took immaculate care of her and to his credit marked page 45 in the Yanmar manual, which states: "The seawater pump turns counterclockwise, BUT the impeller must be installed by turning in the clockwise direction . Throw me a bone here, I have been putting raw water pump impellers into marine engines since I was a kid, always with the vanes set to the rotation they would soon follow on engine start; I should do the opposite in my little Yanni?

 

[Steve Dion]

I have never worried about the engine/pump rotation. As soon as you hit the starter the blades are in the proper direction.

The real problem on theJH motor is getting at the pump and r/r the impeller.

On our HV'36 I installed an inspection door so access is relatively easy. It is still a task getting the impeller out/in.

 

[Mike B]

I didn't see the note on installing the vane the way you mentioned but I just replaced mine in the fall and it couldn't have been easier. Easily accessed, the old vane popped right out and the new right in. I aligned it to match the postion of the old vane. Works just fine.

 

[Rick D]

Oops!

marked page 45 in the Yanmar manual, which states: "The seawater pump turns counterclockwise, BUT the impeller must be installed by turning in the clockwise direction . Throw me a bone here, I have been putting raw water pump impellers into marine engines since I was a kid, always with the vanes set to the rotation they would soon follow on engine start; I should do the opposite in my little Yanni?

Well, you'll have to slap me down! I never remember seeing that and I have always done as you do. Wonder what's up with that?

 

[Warren Milberg]

The misperception that impellors must be installed with vanes facing a certain direction has been around a long time. It continues to be a misperception. Install the impellor, squirt in a little bio-degradable liquid soap as a lubricant, turn on the engine and the impeller blades will sort themselves out in the right direction upon the first rotation....

 

[Brian L.20665]

Lost in translation?

I remember reading this same thing in the manual years ago and pausing for quite a while before proceeding. My interpretation of the info: Note that the instruction is referring to installing the impeller itself and is not referring to the direction of the vanes, so, IMO, feel free to point the vanes the direction you think they should. Furthermore, good luck "turning" the impeller in either direction when installing it. Once the splines on the shaft and hub are engaged, it's not turning. I'm wondering if something got lost when translated from the original language. Finally, I'm of the school that the vanes in that pump sort themselves out in the larger (upper) part of the chamber.
Good luck Capt!
Brian

 

[reworb]

I have a Yanmar service manual. The manual states the impeller should be curved in the direction opposite to the direction of rotation. I attached a scan of the page from the book.

 

[Warren Milberg]

All one need do in regard to whether impeller vanes need to face one way or the other is to take an open raw water pump, put in an impeller and turn the shaft my hand -- first one way, then the other. Bingo, problem solved.

 

[Capt Morgan]

lost in translation....

I have a Yanmar service manual. The manual states the impeller should be curved in the direction opposite to the direction of rotation. I attached a scan of the page from the book.

OF COURSE we all new the answer to this is to put the impellers in as we have been doing for years, and that is obvious reading the text and looking at the picture from the service manual. Maybe in Japanese its not so counter-intuitive!

Thank you everyone for your posts!