Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: 2005 170 Montauk Outboard Mount Bolts and Nuts

Posted by jraney on 07/30/20 - 8:23 PM
#1

I noticed the nuts (on the bolts that attach the 90hp Mercury to the transom) are extremely corroded and cracking. I was wondering if anyone knew the exact size of the nuts to replace are. There are 4 total. 2 on the inside of the transom, and 2 on the outside. They are nylon lined lock nuts. Thank you

Posted by Finnegan on 07/30/20 - 11:12 PM
#2

Mercury engine mounting bolts are 1/2" fine thread, with brass locknuts, to prevent galling(seizure). You can find them on line, but they are expensive, about
$6 each. Use an SS M-12 washer under the nuts/bolt heads on the engine side.

Ace Hardware carries fine thread locknuts in SS, but if you use them be sure to lubricate them with a small amount of grease first.

Posted by jraney on 07/31/20 - 8:52 PM
#3

Thank you!