WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

Folks,

I've fallen heir to a deep/wide 1969 I/O 19ft runabout, which has a DEAD & UNREPAIRABLE 120HP Mercruiser
and
a Model 120/140 Mercruiser outdrive, which is in good shape, currently installed.

I have also found a complete, low-hours, 1985 model, 4-cylinder, Mercruiser 140HP for cheap, that I would like to install in the big runabout.

Does anyone here KNOW if this is a reasonable swap?
(A book from our local public library states that SOME 120 and 140 engines can easily be swapped-out but that others cannot be. - Unfortunately the book doesn't way which will/will not work as direct exchanges.)

I'm hoping that someone here KNOWS for sure what must be done to do this swap, IF it is do-able without spending a pile of money (perhaps) needlessly
OR
If I should seek another engine for the boat?

yours, tex

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

Unless old fiberglass boats are kept inside and out of the weather for their entire life, there's a good chance that the stringers under the fiberglass could be rotted. Your investment in such an old boat may be not a good money spent, as you've still got an old boat.

A 1969 Mercruiser was the first generation of I/O units, and they're substantially different. They later completely re-designed the outdrive where the power trim hoses go. I had a 1969 Aristocraft with this age engine with transom mount problems. I would avoid that old generation I/O outdrive like the plague.

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

Bamaman,

The boat/trailer was stored covered, inside a barn, since it was new, until June of this year when the owner died and the barn/farm was sold. - I've checked out the hull and it's stringers/floor/transom are all solid.

Also, I'm retired and have a great deal more time on my hands than I have money, so I cannot afford to go buy an expensive new boat.

THANKS for your response to my post.

yours, tex

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

It should go fairly easy, but don't expect it to be without a few 'Gotchas' along the way. With almost 20 years of differences, there are bound to be a few problems.

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

Don S,

THANKS for your reponse as well.

I'm hoping that someone here, among our many experienced members, has done a similiar transplant and know what the specific "Gotchas" are.

yours, tex

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

which has a DEAD & UNREPAIRABLE 120HP Mercruiser

Click to expand...

Ayuh,.. What, exactly is the condition that killed the 120 hp motor,..??

Other than the Long Block, are the accessories salvageable,..??

The Gotchas will be with the accessories, not so much the long block motors..

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

Bond-o,

Being run out of water on the trailer, by a nitwitted kid, until it "burned-up". - I would presume that the accessories are OK, but i'm NOT sure of that.

yours, satx

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

Your accessories should be fine, and will swap over. Keep in mind, what he really did was chew up the water pump. but that's nothing to worry about. Mercury used the impeller itself for a number of years on outboards and sterndrives but the pump housing might be different I'm not sure. In any case buy the pump kit given the circumstances. Should be about $40 available right here on Iboats.

Actually The 2.5 and 3.0L were pretty tough designs which came from Chevy 6cyls designs. the 'burned up' engine might just need a head gasket and check for cracks.

Re: WHAT MUST BE DONE TO FIT a 1985 MERCRUISER ENGINE INTO A 1969 BOAT?

matt167; all,

matt: THANKS for your response as well.


to ALL,

IF you think that we "boat freaks" on this site don't have some GREAT and HELPFUL people, I have been offered assistance in doing this job by another local forum member.

yours, tex