Engine Swap

Hello Everyone,

I am looking to swap out the 1991 Mercury 115 on my boat with another (running) outboard motor. I have found several outboards but I was looking at a 1991 Mercury 175. My question is will all the controls and mounting hardware work with the larger 175 motor?

Will the transom mounting bolt holes line up or would I have to re-drill?

Are outboards all made with the same transom mount bolt pattern? Im also looking at other outboards of different makes

Any info would be great.

Thanks

Re: Engine Swap

I'll bump it for you. I don't know. The controls probably yes, holes probably not. Check your BIA certification for max hp. My insurance co gets mad if the engine is larger than the rating on the plate......if you have a weak transom and you firewall it, your boat might get mad too.

Had a friend back in the 60's built his own boat. Put an OMC V4 60 hp on it. First outing, salt water no less, all new equipment, he hammered down on it and the engine ripped the transom intact out of his boat and sank as far as the cables and controls would let it.

Not funny, but happens.
Mark

Re: Engine Swap

Mark/Dnkies, the mounting holes are the same as well as the controls. What's different is the weight and it's a significant amount (100+ lbs). You'll also need to consider fuel tank size. The 115 sips fuel compared to what the 175 will want. Most boats with a 115 run a 20 gal tank and that won't last but a couple of hours when your out. As Mark say's your probably exceeding max hp and that extra weight and hp can wreak havoc on an older transom.

Edit: Almost forgot - You're also going to need to reposition the boat on the trailer or the tounge weight will be way too light after the engine swap. You may even need to move the axle back a couple of inches if the you feel the rig surging when going over bumps.