73 50hp merc lower unit work with 82 40hp merc?

[bitsy4643]

Will a 1973 50 hp lower unit interchange with 82 mercury 40 hp? Thanks

 

[gm280]

bitsy4643, That is a very hard question to try and answer without knowing both engine's serial numbers and configurations. There are a lot of 1973 40HP Mercury engines with one, two, three cylinders. So need more info. Pictures would be great too. :sorry: :noidea:

 

[racerone]

???---The 73 model 50 hp is a 4 cylinder motor.----The 82 model 40 is a 2 cylinder motor.--And yes they may interchange.-----If the 50 hp lower is original it will have a carbon steel driveshaft and not stainless.---Even the 3 cylinder 65 and 70 hp model used the same basic lower unit.----It is best to compare them side by side before laying out the cash !

 

[bitsy4643]

Thanks everyone. Do not have serial number, only lower unit. It has a two bladed prop. It does have a smaller diameter prop shaft and it is not a stainless steel drive shaft, The drive shaft is the same length and the teeth are the same, but the teeth on the 73 do not extend as far down the shaft as the 82 lower unit shaft. Will this present a problem when reinstalling? Also, seem to have some difficulty when reinserting lower unit to align water pipe and drive shaft teeth aligning. Any tips? This is a great site. Thanks

 

[Chinewalker]

If the older unit has a smaller propshaft, it is not a 1973, but earlier still. They made the switchover around about 1970 from the 11-spline to the 13 spline. Not a show stopper, but just a heads up that it may not be as represented to you.

As for the alignment, it's a bit of a chore. Make sure both the unit and upper shafts are in the same gear. I prefer they be in neutral, as it's easy to double check them while in process.

 

[Chief847]

sorry wrong post


Okay a little update. It was the wrong pump. There are two different lower housings and they sent the wrong one. I obtained the new pump and all is well...Well not exactly I put that in a different post.