Swap drives from one boat to another. How many day project?

[matt167]

I’m going to try tugging one boat to the shop this weekend… once I have both boats at the shop and ready. What will I need and how long will it take? I’m pulling out a 1970 Mercruiser 120 and transom assembly ( drive is off ) and installing a 1986 140 with Alpha gen 1. Donor boat is complete so i have to disassemble that one too but figured I’ll do it a part at a time for visual reference. I also want to swap trim pumps… the transom has been redone

 

[Scott Danforth]

Weekend job..... Unless you break a bolt

 

[dubs283]

With a proper hoist and easy access (hatch/bench removed if necessary) and everything goes smooth I'd plan on 20 hrs

 

[matt167]

I’m using an overhead hoist so that’s not an issue

 

[kenny nunez]

You will have to do some transom cutting and drilling. After 75 Merc went to the ear muff style trim/limit sender system.
You might be able to use the inner plate to locate where to drill the 2 holes and give an idea where and how much to cut by holding it in place with the 2 bottom bolts. Or try making a paper template off the doner boat transom cut out.
Hopefully the receiver boat has a solid transom. If it is soft and you try to use it like that you will crack the inner plate from the doner boat. You need at least 2” of solid transom.

 

[Bondo]

Ayuh,..... All great advice,....
As Kenny says, the transom will need so trimmin' to mount the newer transom assembly,.... an aggressive die-grinder did the trick for me,....

I'd devote atleast a weekend to it, in a well outfitted shop,....

 

[matt167]

Im really lucky that the previous owner did a brand new transom correctly ( encapsulated ) he lost interest with the boat when he scored a newer Islander. I noticed when trying to just put it back together that he destroyed the gimbal housing drilling the pins. So that’s the whole reason and I found a boat for the price of an eBay transom assembly

 

[matt167]

Can the original Mercruiser drive from 1970 work with the Alpha gimball housing? Curious if I have a good spare or not. I have the Alpha gen 1 leg of course

 

[Bondo]

Can the original Mercruiser drive from 1970 work with the Alpha gimball housing? Curious if I have a good spare or not. I have the Alpha gen 1 leg of course

Yes,......

 

[matt167]

Thanks. Makes me feel better knowing I have a spare.

 

[matt167]

What all parts am I going to need to replace? I've got all the maintenance stuff in a cart. Just want to make sure I have everything before clicking order

 

[Scott Danforth]

Have a new transom seal?
New aft isolation mounts?

 

[matt167]

I knew about the seal but what are the isolation mounts? are they the 2 fiber washers on the rear motor mounts? I've watched like 4 youtube videos so I have an idea on what to do but every video was incomplete so it's only an idea

 

[airshot]

Add an extra day for unknowns... No matter what I do, I have unseen issues, so I always add an extra day !!

 

[matt167]

I found the rear mounts and bolts. Do I need 3M 5200 along with the foam o ring seal?

 

[Scott06]

I found the rear mounts and bolts. Do I need 3M 5200 along with the foam o ring seal?

no 5200 otherwise you will never get it off.

I think the only place I have seen 5200mentioned is to hold the gasket to the gimbal housing for assembly

 

[JASinIL2006]

I think I used bellows adhesive to secure the gasket in the gimbal housing. It worked quite well.

 

[matt167]

May 18th-19th is the day that hopefully I’m able to swap the drives and at least get the new engine in. I might actually send it down the road to a marine shop to get it serviced if it needs anything. There is actually a shop local that will do older stuff. Boating season is basically here so I’m itching to get it done

 

[matt167]

Do I need 5200 for anything with this swap or anything? I wasn’t planning on shift cables or anything as the assembly was running fine in the donor boat

5200 isn’t available locally anymore except at a couple marine shops farther out so if I need it I have to get it

 

[Scott Danforth]

you shouldnt need it, however its always good to have 5200 and 4000 UV on hand along with permatex #3