Impeller – key vs pin to shaft

[dan-in-tn]

Not to steal your post, but since you have been through this I am fixing to go into the same thing, but in reverse. I have a RDSL-26R (’64-40hp) that I am going to put a RXE-13 (’65 33hp) gearcase on. I will be changing the driveshaft from the long engine into the short shaft. I plan to just cut the woodruff key to drive the wider impeller. I think that is the way to go. The 40hp has the dual bypass water pump. Is all of that done in the water pump? The gearcase hsg. shows the different part numbers Johnny_inFL mentions. Does anyone know what the differences are that cause this part number change? The internal parts are the same as far as I can tell. Just wondering what I am getting into. The A/V plate is all broken off the 40hp from a whale tail application.

Dan in TN

[johnny-infl]

well to start off with, I know absolutely NOTHING about the innards of an outboard !!!
in the past, I have always taken my motors to someone else for maintenance and repairs.
With the encouragement of a renowned member here, "Pappy", and others, of course,
I have gathered up the confidence to dive into a motor (with the proper manuals) and I still
have problems, but are quickly addressed in this forum by the VERY helpful professionals that have "been there – done that".

I guess the line is forming to ask you . . . . WHY ??? is there a reason of not using a 40hp foot ?
They are very plentiful on e-bay ….. Plus, I just acquired a RDS-24L 1962 Johnson 40hp short shaft
that will probably be a parts motor. It looks kinda rough around the edges.

I have had both the 33 and 40 lower units side by side and they are nowhere close to being identical or interchangeable.
The WATER PUMP part number that I have for the RDXE 33hp is 303831
and the WATER PUMP p/n for the RDSL-22 is 312612
and the mounting screws are nowhere close.

and again, I have NO IDEA if what I have is original to the motors or have been changed out over time.

and no, you are not jacking the thread – it is sharing good pertinent information.

[dan-in-tn]

I knew the water pumps were different. (Thick impeller vs thin). Of course hsg. is different. But thought the bolt pattern for the plate was the same. That alone would account for the whole hsg. having a different part number. That’s the kind of info I needed before I start. I have the 33hp parts and didn’t want to buy another gearcase. Changing the water pump bolt pattern won’t be a problem, but I will have to see what if anything else is different before I go ahead. Thanks for the heads up.

Dan in TN

[johnny-infl]

as soon as I get the battery charged to my camera, I can post photos of the two side by side

this is a photo of the 33hp water pump base that had freeze damage
so you can compare this to what you have with the 40hp.

.

[fleetwin]

quote t2stroke:

Not to steal your post, but since you have been through this I am fixing to go into the same thing, but in reverse. I have a RDSL-26R (’64-40hp) that I am going to put a RXE-13 (’65 33hp) gearcase on. I will be changing the driveshaft from the long engine into the short shaft. I plan to just cut the woodruff key to drive the wider impeller. I think that is the way to go. The 40hp has the dual bypass water pump. Is all of that done in the water pump? The gearcase hsg. shows the different part numbers Johnny_inFL mentions. Does anyone know what the differences are that cause this part number change? The internal parts are the same as far as I can tell. Just wondering what I am getting into. The A/V plate is all broken off the 40hp from a whale tail application.

Dan in TN

Dan
yeah, the innards are the same, but the housings are different cuz of the different style water pumps. The 40hp uses the two tube/return system, where the 33hp uses the one tube system. I’m pretty sure the gearcase housing has some of the passages for the return system, it is not just the water pump assy. Is the screw pattern the same? Even if it is, I don’t think the 33hp gearcase housing will work properly on the 40hp, have a look at the water passages under the SS impeller plate.

[fleetwin]

quote Johnny_inFL:

Yes, it is the RXEL-14D motor – removed the 5″ spacer to make it a RXE standard.
the shorter lower shift rod fits well, I did not really “alter” the gear case, just made minor adjustments.
I too am concerned about the looseness of the smaller pin in the larger key slot.
There is no way to tell about any parts being original to the motor. BUT – the gear case part number for the 33 is the
same for a 1960 RDS-22 40hp I am working on: 302520. But, the 33 parts book calls for 593514
and the 40 parts book calls for: 377483. So anything is possible.
When I search for part number 302520 it is not clear as to what it originally fit !!!!
I thought of getting a larger diameter pin or grinding down a woodruff key to accept the impeller slot.
I really hate modifying things that I have no control over nor an easy way to inspect later on down the road without disassembly.
I will take the shaft to my machine shop tomorrow and have a slot ground for the correct woodruff key and be done with it.
NObody likes being stranded on the water due to taking a shortcut on something mechanical.
Other than that, everything is falling into place quite nicely !!
Thanks Fleet – lots of great information there.

Sorry, you are losing me again…There is no 302520 part number. The 33 and 40hp gearcases are definitely NOT the same for these years. Where did you find the part number 302520?

[chris-p]

I have bought motors that were supposed to use the dual pump system, however a previous owner crimped off the return line, and used a single line pump. Not sure why, or if it worked well since I changed it back when I restored it.

I cannot see how you could use single wall gearcase, on a super quiet leg though. Essentially, the 33hp motor is the same as the older 35hp motors. Single wall exhaust housing. The shift rods will be different lengths as well if I remember correctly. Not by much, but enough that you will not be able to adjust at the motor and it will slip, if you can get it into gear at all.

If you get it to work let us know, but Im thinking no off the top of my head. Been wrong before though.

[fleetwin]

Great pictures! Those pictures show the pump bolt pattern is NOT the same so I don’t think Dan’s idea will work out for him. The question I have for Johnny is whether using the impeller with a wider cut out for the key will be an issue. Are you using an OEM or aftermarket impeller? What is the part number? Was a key included with the impeller???

[johnny-infl]

I tossed the bag the impeller came in so I don’t know the mfg. All I know is it takes the key vs the pin.
I will have a groove ground to accept the woodruff key and problem solved.

[fleetwin]

Sounds like a plan buddy!

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