What is this 40hp lower unit from?

[baytonemus]

This is the lower unit that came with the 40352D that I recently acquired.



It is obviously not original. I'm assuming that it's a little older. No water bypass screen or plate, just a small hole there. Also, you can see that the water pump is configured differently with only a single tube going up to the power head and another very short one connecting down to the main intake.

Any guesses as to what motor this might have originally been on?

Thanks.

 

[Daviet]

Re: What is this 40hp lower unit from?

The double water tube lower units were used on the early 60's engines, that's as close as I can get for you.

 

[baytonemus]

Re: What is this 40hp lower unit from?

The service manual that I have for '63 & '64 Big Twins and Larks shows two tubes going up to the power head, so I'm pretty sure it's not from those years.

 

[F_R]

Re: What is this 40hp lower unit from?

That gearcase was used in 1969 and 1970. But the water pump doesn't look right. It should only have one rubber grommet. The other hole is blanked and nothing goes through it. Perhaps somebody just figured they needed to put a grommet in there anyway.

The whole unit can be used on older motors, providing the matching return water tube is used. That is the long one that goes down into the bottom cavity.

EDIT: If the second hole in the water pump isn't blanked off, it has the wrong pump housing cover.

You can see the parts diagram on the BRP website. http://shop.evinrude.com/

 

[baytonemus]

Re: What is this 40hp lower unit from?

Well, you nailed that one (as usual), F_R. I opened up the parts diagram for a '69 40hp at the Evinrude site, then did some comparing and that's definitely what I have. I also have to say, with some embarrassment, that the water inlet tube going up to the power head is not missing, as I said, but still connected up inside the exhaust tube. I guess this falls under the general category of opening one's mouth and removing all doubt.

So, yes, the upper hole on the port side of the water pump is blanked and the grommet is there for no reason. Good place to keep a spare, I guess.

The main reason that I wanted to use the other LU is that I have a gear case extension and already have the longer water tubes for it. I also assumed incorrectly that this LU was older and that the other one may have had design improvements. Seems like it might be the other way around.

Any recommendations?

 

[F_R]

Re: What is this 40hp lower unit from?

Either one is ok, but starting in 1968 (?) they put detent balls in the clutch dog for more positive shifting.

Also, in mid-68, they removed the water bypass plate from the side of the gearcase, making for a stronger casting. The '68 was a one-year case, changing the water return tube on the '69 that you have.

 

[baytonemus]

Re: What is this 40hp lower unit from?

Interesting. So theoretically, the detent balls hold the transmission more securely in reverse, neutral, forward? Was dropping out of gear a problem with the earlier models?

Maybe I should go with the newer LU. Sweating on tube extensions is really not a big deal. Are they supposed to be longer by 5" exactly? It's been awhile since I did that the last time...

Thanks, F_R!