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Lower Unit exchange ?

D

Donewright

Regular Contributor
Greetings,

I have a working 1978 150HP engine with a damaged lower unit case. Part of the Cavitation Plate (I think that is what it is called) is broke. I have a good case from an 80's 150hp and they look nearly identical from the outside. Can I replace my broken '78 with the case from the 80's model? I think the drive shaft comes out when you pull the unit off, can i expect the splines to match? I have attached some images. As you can see, the previous owner was pretty rough on it.

1978 Serial number = 5025197
1980's Serial number = OC248098

Thanks

IMG_2588.jpgIMG_2592.jpgIMG_2589.jpgIMG_2590.jpg
 
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Here is a picture of the shifter from the 80's engine. The levers looks identical to each other, but I won't know for sure until I separate the lower unit of the '78

IMG_2635.jpg
 
Can't get the cavitation plate welded? I guess if you can do a change-over and have one to swap that will be cheaper.
 
I appreciate the responses.

I don't think welding is an option because the broken piece is missing. The previous owner did not have it to give to me when i purchased it. I suppose that since I have the shift shaft from the unit I am going to use as the donor, I could use it if my existing shaft is square.

I ordered a SELOC manual so I can stop guessing at most of this stuff. I think I saw a video on youtube where it showed wires that come out when you drop the lower unit. Has any one had any issues with these wires?
 
I manufactured a shifter shaft without removing the powerhead. It isn't easy but if you are committed enough it can be done. Having said that for my old engine it was easier than removing the powerhead.
 
That will work IF you can do that with the power head on. They sometimes don't come out without a struggle. Worth a try IF you need to.

Jeff
 
Fortunately, I can access the roll pin from the side. Hopefully that will allow me to exchange the shafts if I have to.


IMG_2632.jpg

Thanks for the advice.
 
OK. I have both lower units separated. Everything looks close enough to exchange. But when examining the tip of the drive shaft, it appears that the '78 model has a pin extending from the end of the shaft. The 80's model does not. Would I be able to use the pinless driveshaft in the older engine?

IMG_2644.jpgIMG_2645.jpg
 
Yes IF the "plunger" (sprng-loaded pin) is not broken off.

A bit of explanation: There are two LU designs, one with a roller bearing in the driveshaft (that requires the plunger), and one with a ball bearing that does not.

Jeff
 
Jeff, So you're saying that the preload pin is a requirement of the LU and not something specific to the powerhead? So there is no difference in the powerheads splined receiver that the driveshaft fits into?

I really appreciate your time.
 
I ended up having to remove the midsection from the powerhead in order to swap the tilt trim assembly. I have another thread going concerning that adventure. I did order a new water pump assembly for the lower unit and I am awaiting its arrival to reassemble the lower unit.

I'll give an update one i get it back together.
 
Awesome! The 80's model XR4 lower unit fit perfectly onto the '78 V150! I only had to turn the flywheel a little bit and it slid right into place. The shift shafts were identical.

swap.jpg
 
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