Mariner outboard Rusty Bolts

[Stemar]

My new to me Mariner 3.5 4T has several bolts, some immersed in use, some not, that have shed whatever protection they may have had and are rusting merrily.

Would there be any benefit to replacing them with A4 stainless, or would I be better off just giving them a squirt of ACF 50 from time and replacing with galvanised steel when they get to the point that there's risk they won't be hexagonal next time?

 

[CLB]

I would swap them for stainless, but would use some kind of isolating grease ( I have some in the garage but can't for the life of me remember the name of it right now) if it was going into aluminium. I would also remove, re-coat and replace the bolt at least one a year if you ever think you may need to undo it any time in the future. Once corrosion between a stainless bolt and an aluminium casting start, the bolt will often break before coming undone.

 

[Stemar]

Thanks.

A quick google suggests that it would be a silicone grease, which should keep the water out or a copper grease that should prevent seizing even water gets in. Of the two, I'm inclined to go for the copper grease.

 

[VicS]

Thanks.

A quick google suggests that it would be a silicone grease, which should keep the water out or a copper grease that should prevent seizing even water gets in. Of the two, I'm inclined to go for the copper grease.

Is copper grease suitable for use on aluminium ?
I dont know the answer to that but I prefer not to use it . I note though that Molyslip, the manufacturers of Copaslip, also offer Alumslip, an aluminium based anti-sieze "specifically designed for where copper needs to be avoided (for example where concerns of galvanic corrosion exist)."

My Evinrude has all stainless steel nuts and bolts . I use an ordinary water proof grease ( Ramonol White grease these days ) when reassembling after any maintenance.

 

[CLB]

Tef Gel - That's the stuff I use. I knew it would come back to me. It's incredibly expensive for a little pot, but you only use a small amount. There may be something very similar available for less without the brand name.

Duralac is another similar product, I believe.

 

[C08]

I would swap them for stainless, but would use some kind of isolating grease ( I have some in the garage but can't for the life of me remember the name of it right now) if it was going into aluminium. I would also remove, re-coat and replace the bolt at least one a year if you ever think you may need to undo it any time in the future. Once corrosion between a stainless bolt and an aluminium casting start, the bolt will often break before coming undone.

Sounds good advice - I once helped a friend replace the centre leg section on his Yamaha because the mild steel studs had rusted and burst the sides of the leg. We used stainless threaded rod as replacement studs as there were dowels to precisely locate the leg section.