swapping top half - tower of power

[octaneforce]

i have a mercury 90 tower of power with a blown cylinder, but the lower end is still perfect. i found a mercury 115 tower of power with a bad lower end, but a good running top half. how hard will it be to swap the top halves of these motors? i looked at my 90 quick and saw two bolts under the front of the cowl. anything i should be aware of while doing this? i noticed that the gear shift mechanism might be a little tricky when doing the swap.

 

[Droll]

Re: swapping top half - tower of power

What years are we talking about here ??, if we're talking about swapping the complete power-head... ALL inline 6 engines produced between 1973 and 1988 can be used.

There are some differences over the year but the main parts will interchange.


Arne Kjetil

 

[octaneforce]

Re: swapping top half - tower of power

both motors are mid 80's. i am really not sure of the exact years. i want to swap in the entire top half of the outboard. i am taking the 115 top half and putting it onto my 90.

 

[daveswaves]

Re: swapping top half - tower of power

As Arne said, they should be a direct switch, if the 115 runs well why not put the lower end from your 90 on the 115...a lot less work.

 

[octaneforce]

Re: swapping top half - tower of power

As Arne said, they should be a direct switch, if the 115 runs well why not put the lower end from your 90 on the 115...a lot less work.

sorry, thats what i meant. i just want to use the lower end of my 90. but how do i go about removing the lower end from the 90? wouldnt that be the same as swapping the top halves?

 

[daveswaves]

Re: swapping top half - tower of power

sorry, thats what i meant. i just want to use the lower end of my 90. but how do i go about removing the lower end from the 90? wouldnt that be the same as swapping the top halves?

Assuming the mid section is ok on the 115 you will be better off just removing the lower unit from the 90 and swapping it to the 115. It would be a good idea to change the water pump while you have the lower unit off. I think what may be confusing you is there are 3 sections to the motor, not 2. If you clamped the motor to the boat and removed the power head and the lower unit, the mid section would be what is left on the boat.

 

[Mi duckdown]

Re: swapping top half - tower of power

You really need to know the exact year of both motors. Got serial numbers?

 

[octaneforce]

Re: swapping top half - tower of power

Assuming the mid section is ok on the 115 you will be better off just removing the lower unit from the 90 and swapping it to the 115. It would be a good idea to change the water pump while you have the lower unit off. I think what may be confusing you is there are 3 sections to the motor, not 2. If you clamped the motor to the boat and removed the power head and the lower unit, the mid section would be what is left on the boat.

ohh okay that makes sense. thanks for clearing that up. what do i have to do to remove the lower end? ill have to take a look at my motor tomorow morning.

 

[Mi duckdown]

Re: swapping top half - tower of power

The gear ratio can be different on the lowerends that is why you need to have the serial numbers of both motors to cross reference.

 

[daveswaves]

Re: swapping top half - tower of power

True, it is possible, especially if one is early 70,s. It sounds like they are both mid 80,s though and if the lower units look the same physically from the outside, newer swept back design, then they are likely both 2:1. Pictures would help, of both engines.

 

[Chris1956]

Re: swapping top half - tower of power

Sounds like you need a service manual, since you should rebuild the waterpump whne you have the gearcase off. The Gearcase is removed by removing 5 nylon lock nuts and a bolt. Of course the bolt is hidden under the zinc anode. The zinc anode is removed using a thin wall 3/8" drive socket or an allen wrench.

to reinstall the gearcase, the driveshaft splines must be greased and mated to the crankshaft splines. Ditto for the shiftshaft splines.

 

[octaneforce]

Re: swapping top half - tower of power

heres the donor motor:



Uploaded with ImageShack.us

heres the motor i have right now:



Uploaded with ImageShack.us

 

[daveswaves]

Re: swapping top half - tower of power

There is no reason that the two lower units will not swap over.

 

[octaneforce]

Re: swapping top half - tower of power

okay thanks alot! i will let you guys know if i run into anything during the swap

 

[merc850]

Re: swapping top half - tower of power

While you're working on the swap check out this awesome ebay deal http://cgi.ebay.com/ebaymotors/COWL...8835303QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear