Proofing against corrosion with threads?

[mr-asa]

I was just wondering if there was anything that can be done to help prevent against corrosion? Mainly from the point of view of protecting your engines from snapping bolts down the road.
I was thinking that some sort of anaerobic thread sealer might help, but I’m not sure how it would react long-term between aluminum and ferrous bolts.

[chris-p]

Depends on the bolt? Any in particular we are talking about here?

Bolts like the SS ones for the impeller housings get a coating of OMC Gasket Sealing Compound, as does head bolts. Powerhead bolts get coated before install and torque. I use 3M 847 on them.

Or are we just talking non normally coated bolts, like ones holding trim and such? I suppose the OMC Gasket Sealing Compound could be used on them as well, as they are fine on the head bolts. I don’t have to worry about salt water, so don’t bother with my own motors, but I realize the playgrounds you run in are much different than mine.

[mr-asa]

Just in general.
I’ve been taking apart a lot of stuff recently to clean parts and relube before operating it. Been on my mind.

I try not to run in salt water, but eventually I’m going to have to take the little lady out somewhere so she can go fishin.

[jeff-register]

Mr. Asa,
I use locktite brand steam fitting thread anti-sieze. Made for extremely hot, (dry steam) hospital work. I use on exhaust system & all bolts of an outboard. Comes in a coffee can sized with a brush in the cap. Has the color of silver paint & thick as toothpaste. On another site the guy uses stainless studs in the exhaust system with allen head fittings on the end of the stud. With anti seize[ & stainless studs & nuts he always gets it apart.
Look for a Locktite store on the web. They have all kinds of cool stuff in the store. /size]

[chris-p]

Yeah I have cursed a few slotted exhaust bolts in my time. 😉

[fleetwin]

Just about anything is better than installed dry. The important thing to remember is not just to coat the threads that are actually engaging into the metal, be sure to coat the shank/threads all the way up to the bolt/screw head. Oftentimes the salt builds up in this area and seizes the bolts/screws. Sounds like you have fresh water motors, but it is important to clean off the complete bolt shaft and the unthreaded hole with a round file, then run the appropriate tap through the threads. Cleaning the bolts/screws up on a wire wheel is usually all that is needed instead of running the bolts/screws through a die.
The OMC gasket sealer in a can is ideal for corrosion protection, the brush applicator makes it easy to apply. The OMC/merc grease would be my next choice. The OMC 847/type M would work, but is messy. I have never had trouble removing any hardware once I have cleaned it and treated it with gasket sealer, and salt water engines are all I ever worked on.

[jeff-register]

Fleetwin,
I believe you are saying Do as I say, not as I do IE, The factory used nothing but who back then thought after 20 years they would still be around! 😆 I have never used sealer but why not!! Don’t forget the bottom end tap for the holes too & remove the scrap thread chunks. The antisieze I have used on Corvair & V.W. stuff & still came apart after we blew them up. More like sanded them at Baha!!

[archangel]

Wasn’t there some discussion in an earlier thread — possibly on the lost boards — that suggested that copper or nickel anti-seize was a no-no, especially for salt-water motors, as these created a galvanic reaction that actually exacerbated the corrosion?

[fleetwin]

quote Archangel:

Wasn’t there some discussion in an earlier thread — possibly on the lost boards — that suggested that copper or nickel anti-seize was a no-no, especially for salt-water motors, as these created a galvanic reaction that actually exacerbated the corrosion?

YES! Some types of anti seize could actually cause MORE corrosion due to the dis-similar metals. But, I’m sure they make products that are compatible with the aluminum and salt water, and I just didn’t want to dismiss the whole anti seize product line.

[fleetwin]

quote Jeff Register:

Fleetwin,
I believe you are saying Do as I say, not as I do IE, The factory used nothing but who back then thought after 20 years they would still be around! 😆 I have never used sealer but why not!! Don’t forget the bottom end tap for the holes too & remove the scrap thread chunks. The antisieze I have used on Corvair & V.W. stuff & still came apart after we blew them up. More like sanded them at Baha!!

Well, the factories don’t coat the threads of fasteners, probably due to cost considerations and paint problems when the sealer gets on surfaces that get painted.
And, in this case, I definitely do as I say!

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