Engine Change Question - Will I need a new prop

[SailMaster]

Hello all,

Here is what we are doing.

We are replacing a Volvo MD2B with a Yanmar 3HM35F. I do not have transmission numbers. We are using the tranny that came with the engine. My engine mechanic has run the engine once to check engine rotation. It turns counterclockwise.

My question is, will the Yanmar tranny turn the prop in the same direction as the engine when operating in forward gear?

 

[Terry Cox]

You will need the transmission model number because, if it is a Kanzaki brand, they rotate either clockwise or counter-clockwise, depending upon application.

 

[kloudie1]

The 3HM Yanmar engine "normally" rotates counterclockwise when looking at the flywheel. The transmission gear reverses that direction so the propeller would be "normally" turning clockwise looking from stern while in forward gear. I don't know what direction the Volvo turns..
The Yanmar will need a Right Hand (RH) prop..
You will need to look at the gearbox ratios if trying to use the old prop. If they are reasonably close (a quarter point or so) then you can probably go with the old prop .. It will probably have to be re-pitched to get it to work with the new setup. Good Luck with it.

 

[JohnShannon]

MD2B looks like 23 HP at 2500 rpm but apparently is a clockwise engine?

http://www.volvopenta.com/volvopent..._engines/Pages/out_of_production_engines.aspx

The operators manual is a free download, don't worry about the buy button (printout?)

In the end if the rotation direction is the same, and the new engine makes more power than the old engine at a given RPM it should work.