Frozen Pulley Sheaves

[JohnV]

Hello--
The older aluminum and stainless fiddle blocks for my backstay tensioners are siezed--the plain nylon sheaves turn with difficulty if at all. I assume it's due to corrosion due to dissimilar metals.
The rest of the blocks on the 30-year-old boat (recent purchase) are Shaeffers and spin freely. The ones in question are marked "Slater". (Never heard of them--have you?)
Anyway, I've tried Kroil, PB Blaster, working them by hand and soaking in vinegar--no joy.
I am considering drilling out the rivets, cleaning up as necessary and replacing the rivets with stainless machine screws & red locktite. Any feedback on that idea?
Any other suggestions? They look good otherwise and would much rather spend my refitting money elsewhere if I could get them freed up again.
Thanks for any help.
John V.
Alajuela 33

[forsailbyowner]

If they're all stainless and aluminum I'd try heating the aluminum sheaves slowly and getting some kind of mechanical bite to turn them. Like taped up channelocks.

[JohnV]

Thanks for the reply. The sheaves look like nylon--only the cheeks and straps are metal. I had gotten them to turn a little with taped channellocks, also by taking a few turns of rope. But that doesn't loosen them up, unfortunately.
JV

[Jim Cate]

G'Day John,

I have had to drill out the rivets in many an old block. A PITA, but no real worries in doing so. The replacement bolt will likely be stronger than the rivet, and once done, regular service can be done to keep them really free running. Go for it!

Cheers,

Jim and Ann s/v Insatiable II lying Coasters Retreat, NSW, Oz

[Marinheiro]

If you are at point of last resort, you could try putting them in a pot of boiling water for half an hour, might wash out the salt but hopefully not soften the plastic.
On the other hand why not just buy some replacements from Garhauer, the prices for their gear are remarkable, particularly given the quality. I bought a couple of 10,000lb swl blocks from them for about quarter what you would pay elsewhere.

[JohnV]

Thanks for the replies.
Marinheiro, I'll look seriously at Gerhauer if I have to go that route but I'm pinching pennies where I can. I'll try soaking them in hot water--maybe just short of boiling.
I'd assumed the problem was corrosion around the bearing/bushing--but maybe it is just salt.
Jim, my concern about using bolts, having no experience with that fix, is whether the rotation causes the nut to back off? If that's not an issue, then I like the idea for the reason you mentioned--you can always open it to work on it.
John

[aboutgone]

Either repair the block or get a new one....if you re bush the old...that's good....if you buy a new one your good too......7.00 vs 40.00 but there a lot of blocks out there for 15$ that have a working load of 8 to 9 hundred #.....the choice is yours

[Jim Cate]

Originally Posted by JohnV

Thanks for the replies.
.
Jim, my concern about using bolts, having no experience with that fix, is whether the rotation causes the nut to back off? If that's not an issue, then I like the idea for the reason you mentioned--you can always open it to work on it.
John

John,

Never has been a problem for us. The Locktite will certainly suffice to prevent unscrewing the nut.

Cheers,
Jim

[JohnV]

Thanks for the help, Jim. That's the plan, then.
John

[Jim Cate]

John,
One last thing: use a 316 bolt for the replacement... much less chance of crevice corrosion in the access-restricted areas inside the cheeks, etc.

Cheers,

Jim

[JohnV]

Thanks, Jim, I'll try to find them.
I drilled out a rivet today and found the sheave glued to the cheeks with what I assume is salt encrustation. It would be nice if something dissolved that stuff. Water doesn't seem to touch it.
John

[DeepFrz]

Water and vinegar will dissolve it, or there are proprietary solutions that you can buy at most any major dept. or hardware store.

[JohnV]

Thanks, DeepFrz. I've actually had them soaking in white vinegar for the better part of a week, with no results. The salt is caked in pretty thick in the one I've dismantled. I've got them in hot water now. Apparently it works best if it's hot and changed periodically--it gets less effective as it absorbs the salt.
I'll look for something in the stores. I'll drill out the rivets on any that don't loosen up as a result of one last try at soaking.
John