Yanmar impellor

[Sailfree]

Manual says pump turns anticlockwise but install impellor by turning clockwise.

Surely this means blades are facing forwards while I would expect them to effectively be trailing!

What do I not understand or am I being stupid!!

 

[VicS]

Manual says pump turns anticlockwise but install impellor by turning clockwise.

Surely this means blades are facing forwards while I would expect them to effectively be trailing!

What do I not understand or am I being stupid!!

Dont worry about it. The vanes will sort themselves out as soon as you run it,

 

[Sailfree]

Dont worry about it. The vanes will sort themselves out as soon as you run it,

Thanks but I have a terrible affliction. I like to understand both what I am doing and why!!

If the vanes sort themselves out why bother with specific
highlighted instructions in engine manual??

 

[VicS]

Thanks but I have a terrible affliction. I like to understand both what I am doing and why!!

If the vanes sort themselves out why bother with specific
highlighted instructions in engine manual??

Fit it how the manual says then.

I would have looked at the manual to try to understand but you dont say what engine.

 

[Sailfree]

Fit it how the manual says then.

I would have looked at the manual to try to understand but you dont say what engine.

Yanmar 4JH3-TE

 

[Sailfree]

Why are they so difficult to fit? I epoxysied a short bolt on the impellor threaded end and still could not get it out. Back to bent screwdriver end and levering it off a bit at a time on alternate sides. Undoing alternator and calorifier hose helped me see what I was doing.

New one had to be tapped on to sit fully down!

Installed as per manual but uncompressed side has blades end free so expect them to go into trailing mode.

I assume mine is correct with spindle offset to form a pump chamber and shaft is not bent!!

 

[VicS]

Yanmar 4JH3-TE

OK

You have presumably read this

The seawater pump turns in the
counterclockwise direction, but the
impeller must be installed by turning
in the clockwise direction. If the
impeller has been removed for any
reason and must be reassembled, be
very careful not to make a mistake
and turn it in the wrong direction.
Additionally, if the engine is being
turned manually, be careful to turn it
in the correct direction. Incorrect
turning will twist the impeller and
damage it​

in the owners manual.

That seems clear enough but totally illogical "

The workshop manual gives no guidance but includes this diagram which indicates that the pump actually turns clockwise



I guess I could find a diagram of the gearing to work out which way the pump really does turn but the easiest way will be to turn the engine by hand in its normal direction and watch to see which way the pump turns.

I'd suggest you then install the impeller by turning it the same way ............ Maybe someone will know better ?

 

[RichardS]

I assume mine is correct with spindle offset to form a pump chamber and shaft is not bent!!

The spindle should only be offset in the sense that part of the circle that would be transcribed by the end of the vanes is taken up by a cam which forces the blades into a bent orientation as they pass over the cam.

I compress in the blades of my impellers with a cable tie when I fit them. It's then just a matter of pushing in the impeller as the cable tie pushes off. When I tighten up the cable tie some blades bend one way and some bend the other but it doesn't matter as it all sort its self out when the engine starts, as Vic says.

Richard

 

[Tranona]

Why are they so difficult to fit? I epoxysied a short bolt on the impellor threaded end and still could not get it out. Back to bent screwdriver end and levering it off a bit at a time on alternate sides. Undoing alternator and calorifier hose helped me see what I was doing.

New one had to be tapped on to sit fully down!

Installed as per manual but uncompressed side has blades end free so expect them to go into trailing mode.

I assume mine is correct with spindle offset to form a pump chamber and shaft is not bent!!

You can buy an impeller remover from Jabsco although i have a plastic hook type that came with a Speedseal cover. They need to be a close fit which inevitably makes them hard to remove.

I agree the instructions sound nonsense. As RichardS says the vanes sort themselves out as soon as the engine turns with no ill effect.

When you have done the job successfully once it will cease to be a cause for concern!

 

[tudorsailor]

You can buy an impeller remover from Jabsco although i have a plastic hook type that came with a Speedseal cover. They need to be a close fit which inevitably makes them hard to remove.

There are two types of impeller. With and without a threaded in the central part. The one with a thread is designed to be removed with a Yanmar impeller removal bolt


Much easier where space is limited

TS

 

[RichardS]

There are two types of impeller. With and without a threaded in the central part. The one with a thread is designed to be removed with a Yanmar impeller removal bolt
View attachment 72559

Much easier where space is limited

TS

I've not encountered the threaded sort before ..... but presumably the impeller itself is still just a push fit onto the end of the shaft?

Richard

 

[PetiteFleur]

I modified a cheap pair of long nose pliers by heating the ends and bending them inwards. Easy to grab the central rubber boss and just pull off the impellor. Works a treat, replacing the same way, just easing in the vanes. I don't bother to align the vanes, they sort themselves out.

 

[tudorsailor]

Yes the impeller slides onto the spindle

FWIW, I also bought adapted needle nose pliers. In my engine room there was not enough room to use them.

TS

 

[alexsailor]

I have the same engine.
As written before it does not matter how you fit in impeller blades.
When I am changing it (300hours or more) the blades are all in the right way.
I also bought that Yanmar tool for removing impeller. Works perfect but is by far the most expensive screw I ever bought

 

[Mistroma]

I made one for around £3 and have used it for last 9 years. Works well.

http://mistroma.com/ImpellerExtractorTool.html

 

[Sailfree]

I made one for around £3 and have used it for last 9 years. Works well.

http://mistroma.com/ImpellerExtractorTool.html

Thanks for that.

Guess what I will have made before next impellor replacement.

I also have speedseal cover - great bit of kit. Sad to see they have stopped trading due to ill health

 

[scottie]

I have the same engine.
As written before it does not matter how you fit in impeller blades.
When I am changing it (300hours or more) the blades are all in the right way.
I also bought that Yanmar tool for removing impeller. Works perfect but is by far the most expensive screw I ever bought

Volvo used to do one at a fraction of the yanmar price
Getting the impeller with the thread is the problem

 

[Sailfree]

I've not encountered the threaded sort before ..... but presumably the impeller itself is still just a push fit onto the end of the shaft?

Richard

While I had a bolt on the end I could not slide the old one out. Needed a screwdriver with bent end to prise it off and a little each side - just like the first time I did it! Bolt not much help.

Difficulty fitting new one and needed gentle taps with hammer at centre to seat it back!

Would hate to do it in a sea!

While I had nothing but problems with Volvo engines I could always change the impeller easier!

 

[jiris]

I also believe the stress on the direction of rotation in the manual is exaggerated. I installed impeller a few times and never gave a damn. Never any problem. My confidence stems from from experimenting with out of the engine pump. Can't see a way, how the impeller could be damaged, as long as the blades are properly lubricated by a silicone grease before installation. Another point is, the engine often turns some 180 dg the wrong way anyway during a stop operation or failed start. It, obviously, doesn't damage the impeller either...

 

[Ninia]

The Yanmar impeller removal tool looks very similar to a bicycle crank puller tool / self extracting crank bolt, these can be bought for a few quid. They seem to have the correct M18 size available.