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2006-2009 Range Rover Sport
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Discussion Starter #1
As some will know the water pump on the Rover serpentine belt engines turn the opposite direction to V belt driven water pumps. Looking from the front of the engine the serpentine water pumps turn counter clockwise.

I have this water pump to go onto my engine.



The wiggly red arrow indicates the direction the impeller turns when looked from the rear.

Here is a different view of the impeller.



Notice the direction of the teeth on the impeller.

Here is my confusion - when this impeller is turning in the correct direction as per the red arrow the teeth seem to be the wrong way around - basically the impeller seems to be running backward - as if the water pump should be turning the opposite direction.

Now the shown pump is supposedly the correct pump and I have found the same examples in the internet being sold for the same application.

So can someone explain why the impeller seems to turn the wrong way on these pumps.

Thanks

Garry
 

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1995-2002 Range Rover P38A
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417 Posts
From the front of the engine I would say the engine fan turns clockwise. so tat looks correct.
 

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1995-2002 Range Rover P38A
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3,952 Posts
But it doesn't. The water pump is driven from the back of the serpentine belt so turns anticlockwise.

Thread for the viscous coupling will be different too, standard RH thread on a serpentine belt version and LH thread on a Vee belt version.
 

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1995-2002 Range Rover P38A
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Hi

The red arrow in the photo is the right direction.impellers of most centrifugal pumps are with the impeller blades bend backwards opposite the rotation direction. With vector diagrams for speed radial and centrifugal you can find the optimised angle of the impeller blades. So there is one speed where the water will exit the impeller without creating turbulence and it is here that the maximum efficiency of the pump is reached.

Best regards

Jos
 

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2006-2009 Range Rover Sport
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Discussion Starter #5
Thanks for the comments - the impeller and fan does turn counterclockwise as mentioned on the back of the serpentine belt.

Jos - thanks for your explanation - clearly the blades as shown are correct which to me seems counter intuitive. I thought the answer may have been cavitation hence the reversed blades but your response seems to be the right answer.

Cheers

Garry
 

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1995-2002 Range Rover P38A
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If you flip the fan in the top pic it will then be as it is supposed to be on the car then the blade will be clockwise as the engine is supposed to turn.
 
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