86 90hp merc installation

[Fortech]

I installed a larger motor on my 17ft Mako. I'm looking at the manual and the pictures seem to have the two upper engine to transom bolts going opposite of the lower. Bolt to the inside nut to the outside on the upper, reverse on the lower two. It also mentions using marine sealant on the shank but not the threads of the bolts. Do I use 3M 5200, or is there another recommendation. I haven't put the boat in the water yet, so no harm done. Just want to be sure that I do not get water in the transom. Any input would be appreciated....<br />Tony

 

[fishingdan]

Re: 86 90hp merc installation

Maybe someone else has a a good reason, but I don't think it matters which way the bolts go. I think it is mainly a matter of convenience (i.e. which side is easier to work on). I think my engine (50hp 1985 merc) has all of the bolts outside and nuts inside. When I mounted the engine, it was easier to push the bolts through. <br /><br />Definitely use sealent on the bolt shafts and the threadbody on the outside. Too much will not cause any problem. I would use 3m 4200 or equivalent instead of 5200. 5200 is for permanently mounted things. 4200 is a great sealent for bedding things and for sealing around screws. <br /><br />To really make sure the hole are sealed, drill the transom holes (if a new transom) and seal the inside of the holes with epoxy. <br /><br />Good luck