Engine accessory bolt replacement advice sought

[scross]

Can I replace some of the Yanmar 4by2 accessory bolts (engine cover bolts, etc.) that have significant surface rust with stainless bolts without any electrolysis issues?

 

[BB marine]

I would remove the old rusted bolts clean them up. Inspect the condition of the bolt head and threads. If the bolts still look good, paint the visual exposed portion of the bolt with a good metal primer. lubricate the threaded portion of the bolt with an anti corrosive grease or thread compound, install. After install, color match paint the exposed bolt head. If the bolt has damage I would replace it with (in like kind) bolting and use the same process as the old bolts. Mixing metals in a marine environment could present issues. When I was rebuilding marine engine after the engine was dissembled I would clean up all bolting, All external bolting after cleaning and inspecting I would prime. I found it easy and fast to do by using a 2' long 2 by 4 that had 3 rows of holes, 1st row had 7/16 holes in it for 3/8 & 5/16 bolts, 2nd, 9/16 holes for 1/2 bolts, 3rd row 11/16 holes for 5/8 bolts. I inserted all the bolts in the holes put the board in a vise and primed all of the heads with rattle can metal primer. Process took about 5 minutes and primed a lot of bolts.

 

[Brian B]

Here's the Yanmar paint for your project
http://www.oldportmarine.com/store/p247 ... Paint.html

 

[scross]

Thanks Brian! I’ll try rehabing the old ones. I have a very mild polishing bit for my drill press that should take most of the rust off without removing sound material.