1972 Evinrude 4hp yacht twin conversion to short shaft

[OLDIRON]

Hello. I just acquired this motor because it was cheap (20 bucks). I really don't have a use for it as it's configured for a high transom. It has a 15" extension lower leg. Never seen anything this tall. It runs great. So good in fact I want to keep it. And I will keep it if I can covert it to a short shaft. I've done a little research and I can buy a shaft and water tube, but my question is which shaft and tube? Can this even be done successfully? Do I also need a shorter leg, or can I just mount the gear case to the upper leg and remove the extension? I know, a lot of questions, sorry. I'm going to replace the impeller just because, so this would be an ideal time to make the change. It is a model 4236S-EO1965. The O may be a zero. I can't find the meaning of the last numbers in any parts website. Please let me know if a conversion is possible. I would really like to keep this nice little motor in my stable. Thanks in advance. and have a great day.

 

[hardwater fisherman]

I have 2 short shaft 4hp and would love to have a long shaft..In my area they are rare.. If you want to convert it to a short shaft it might be cheaper to find a non running short shaft motor for pieces.

 

[F_R]

The 15" extra-long shaft was an accessory kit for sailboats. We sold a couple of them back in "The Day". Sure, you can convert it back to standard short shaft. You will need a short drive shaft and water tube. I think you will need to remove the powerhead to replace the water tube, unless you can figure a way to get in there and cut 15" off the existing one. Will need powerhead gasket if you remove it.

 

[F_R]

15" Extension kit was part number 384121.

4236S is the model number (as it left the factory as a short shaft before kit installation)
EO1965 is the serial number.

 

[OLDIRON]

The 15" extra-long shaft was an accessory kit for sailboats. We sold a couple of them back in "The Day". Sure, you can convert it back to standard short shaft. You will need a short drive shaft and water tube. I think you will need to remove the powerhead to replace the water tube, unless you can figure a way to get in there and cut 15" off the existing one. Will need powerhead gasket if you remove it.

Ah, so can I assume that this motor did not leave the factory with the extension? It was an aftermarket kit. This is good to know. So if I can order a shaft and tube for a standard 4236S they should be the short version, correct? Since I got it so cheap I don't mind spending a little money to get the motor I want. Working on this motor will be breeze compared to my 55 and 40. Looking forward to it. Thank you very much for your help.

 

[OLDIRON]

Thank you everyone for your help. If I can pull this off I will post some pics. Have a great day all.

 

[F_R]

OK, posting the contents of the extension kit. You will need a #10 gasket, a #6 drive shaft, and a #13 o-ring for a 4236S short shaft motor. You will simply cut 15" off the bottom end of the water tube. All the other pictured parts are unique to the extension kit and will no longer be used.

In case you wonder, the transom plate was included because the leverage of the prop so far down would torque the motor off the transom if steered to one side at full throttle without better restraint.

 

[oldboat1]

Keep the parts, incl. the part of the water tube -- makes the motor more attractive to a buyer, or should. There are a few ways to reattach the tube piece, making the motor very versatile.

 

[OLDIRON]

Well this is not going as easy as I had hoped. The shaft I believe is stuck to the head. I could take the bolts that hold the motor on the upper leg, but then what, it would still be stuck to the shaft. Has anyone had any luck hanging the gearcase from a rafter, and letting the head drop a foot or so? It may ruin the pump housing, but so what? Any thoughts?

 

[OLDIRON]

OK, posting the contents of the extension kit. You will need a #10 gasket, a #6 drive shaft, and a #13 o-ring for a 4236S short shaft motor. You will simply cut 15" off the bottom end of the water tube. All the other pictured parts are unique to the extension kit and will no longer be used.

In case you wonder, the transom plate was included because the leverage of the prop so far down would torque the motor off the transom if steered to one side at full throttle without better restraint.

Mine does not have the plate you are referring to, but the diagram you showed raises a question. I can't get the lower unit off, it appears to be stuck I believe to the motor, looking at your diagram, is it possible that it may be stuck to that extension? Can't imagine that but I have never dealt with an extension.

 

[oldboat1]

edit.

 

[F_R]

Mine does not have the plate you are referring to, but the diagram you showed raises a question. I can't get the lower unit off, it appears to be stuck I believe to the motor, looking at your diagram, is it possible that it may be stuck to that extension? Can't imagine that but I have never dealt with an extension.

Will the lower unit drop down from the extension even a little bit? It should, even if the drive shaft is the problem. If it won't move or wiggle at all, I'd guess there is a bunch of corrosion build-up between the water pump housing and extension housing.

A potential drive shaft problem other than rusted splines is the shaft has a center support bushing, #'s 3 and 4, in the extension. Maybe it is not sliding through that. Even so, the powerhead should lift off if the splines aren't rusted.

BTW, the plate is screwed to the boat, wherever that is.

 

[OLDIRON]

Last night I hung the motor like a side of beef from the rafters. Took the upper and lower extension bolts out and turned it enough to see the shaft and spray PB down it. I have a garbage can half full of aluminum cans under it just incase she drops while I'm gone which I seriously doubt will happen, she's stuck pretty good. I did give it some good raps with a rubber mallet and looks like this morning it separated 1/4 to 3/8" from where it was last night. If this doesn't work, I'll hook it to a come along and rip the shaft out of the waterpump housing and buy a new one. I think patience is the key here, and first do no harm. I'll let you all know how this method worked out, if at all.

 

[OLDIRON]

SUCSESS !! She broke loose. much sooner then I had expected. Hanging it from the rafter and PB did the trick. Kept driving plastic shims into the gap. Now I go into the parts hunting stage for a short shaft.