Mast sheaves wont turn......

[PetiteFleur]

Had the mast down this winter to check it over etc and do one or two jobs. The job I've been putting off is unjamming the forward facing (Genoa + spare)two sheaves at the mast (head. They are aluminium, but the shaft is not visible at all so I'm assuming it's probably stainless which was fitted when the top cap was welded on during manufacture 31 years ago. Any ideas how to unseize the sheaves? My boatyard mentioned lots of WD40 + tapping the sheave around the shaft but I'm not sure - what if the shaft is Aluminium?
They have been seized for at least 5 years - all suggestions welcome.

 

[sailorman]

Had the mast down this winter to check it over etc and do one or two jobs. The job I've been putting off is unjamming the forward facing (Genoa + spare)two sheaves at the mast (head. They are aluminium, but the shaft is not visible at all so I'm assuming it's probably stainless which was fitted when the top cap was welded on during manufacture 31 years ago. Any ideas how to unseize the sheaves? My boatyard mentioned lots of WD40 + tapping the sheave around the shaft but I'm not sure - what if the shaft is Aluminium?
They have been seized for at least 5 years - all suggestions welcome.

the spindle is unlikely to be aluminium. there must be some way of gaining access to the spindle ends to punch it out after liberal soaking in penetrating oil or even heating with a gas torch to break the seal

 

[rob2]

I think a liberal dousing in boiling water might help. For one it should wash some of the salts off and secondly the heat may crack the parts apart. Once you've got the sheaves turning,a few sessions with WD40 will help. Long term, though, it would be better to get the pin out so you can properly grease everything. Before you ask, yes I've done it and now I check and spray them every year.

Rob.

P.S. Do you know what make of mast it is? Some of the manufacturers have exploded diagrams of their sections and fittings on their websites, which might help. My Z Spars mast has a bolt on cap which holds the pins in place.

 

[wilkinsonsails]

Before you douse it in the usual lubricants. Aluminium oxide which is usually the problem will dissolve with copious quantities of hot water,thats usually on the sides of the sheaves not often on the pins.Try that.
Cindy

 

[Ariadne]

give it good wash with plenty of cold fresh water, then give it loads of WD40 let it soak in and give some more. Carry on doing this patiently for 3 days or more then tap the spindle out gently with a slightly smaller drift. Make sure you keep it lubricated with loads of ..........WD40 as you do it.

Best of luck, it will come out. Then get some new S/S sheaves made up and reassemble it.

 

[wilkinsonsails]

Beaten to it by Robt!

 

[Neil_Y]

Can't quite understand all this WD40 worship.
More recently there have been some excellent devlopments in chemical treatment of corrossion by products which cause seizing.

The current technology in the area of releasing corroded seized parts is ACF-50

This attacks the corrosion cells.

The only reason I know is that I discovered this some 8 years ago when looking for a solution to seized Aluminium threads that had been exposed to salt water for ten years.

It really works.

WD is a great water dispersant and thin lubricant, but so is heat and a thin oil.

 

[VicS]

I agree hot water , boiling hot, is the first thing to try but I am afraid aluminium oxide is not actually soluble in it.
With luck it will expand the aluminium sheaves sufficiently to free them but to get them truly free you will have to remove them and clean out all the oxide.

Follow the hot water treatment with a penetrating fluid such as ACF-50 since that is recommended.

The big trouble will be that unless you can free them initially youll not be able to drive the spindles out.
Care will be needed to drive them out anyway, they may be solid in the masthead crane as well, or you will break that.

 

[Neil_Y]

Actually...
ACF-50

Active Thin Fluid Film chemistry penetrates corrosion deposits where it chemically emulsifies and displaces the electrolyte. This isolation process keeps the corrosion cell deactivated.

 

[wilkinsonsails]

Hot water does seem to make the oxide bit go away ,when Ive had the problem What in your chemists cupboard would dissolve it then Vic?
Cindy

 

[Neil_Y]

Hot water does seem to make the oxide bit go away ,when Ive had the problem What in your chemists cupboard would dissolve it then Vic?
Cindy

I'm not Vic but...I quote
ACF-50 actively penetrates through the corrosion deposits to the base of the cell where it emulsifies and encapsulates the electrolyte, lifting it away from the metal surface. ACF-50 then dispels this moisture and provides an atmospheric barrier which prevents any further moisture contact, thereby keeping the cell inactive. This compound continues to actively penetrate and "creep" into the tightest of seams, lap joints, micro cracks and around rivet heads, dissipating the moisture, even salt water, in these corrosion prone areas. These unique abilities of ACF-50 remain effective for 12 months, gradually disappearing as it is chemically consumed.

 

[VicS]

According to Kaye and Laby it is very slightly soluble in acids and dilute alkalis (Its amphoteric) I don't think I'd be very anxious to try either!

 

[rob2]

I think the reason that boiling water has worked for me is that it does remove any sea salt and through differential expansion it causes the aluminium oxide to crack away from the remaining aluminium. I've seen the corrosion peel off in sheets (albeit small ones).

Rob.

 

[wilkinsonsails]

Hot Vinegar ?,just thinking of stuff we might have available on board.Must try that sometime.
Cindy

 

[seadog30]

All of the above plus -

Had the same problem a couple of years ago.

If the hot water and oils dont work try vvery gently tapping with a pin hammer, poking with a screw driver (also gently) and if that does not produce enough movement to let the oils do their job try tapping the pulley with a small punch to rotate the pulley.

As soon as you get any movement the oils will free it up and allow you to work the pulley free by pulling the halyard backwards and forwards.

When all ok use spray silicone generiously until you put the mast back in place.

Good luck

 

[Neil_Y]

Spray leave and take apart. It is not a penetrating oil it is chemical treatment of the oxide to disolve it, and prevent new corossion, with thin film lubricant.
http://www.sportouring.com/gallery.php?sectionHeaderActive=2606&rangeChoosen=272

 

[vyv_cox]

I have owned two Kemp masts of around the same age as yours and both suffered the same problem. There was a nylon bush forming a bearing on each sheave. Over time the nylon had swollen due to contact with water. I took them out, reamed the nylon and refitted them. No more problems.

 

[RivalRedwing]

Hot Vinegar ?,just thinking of stuff we might have available on board.Must try that sometime.
Cindy

Hot vinegar will not touch a pure aluminium oxide - it is a superbly inert compound that is exceedingly resistant to simple chemical attack, hence its widespread used in manufacturing and the chemical industry. If it is not pure but rather an aluminium hydroxide then there is a slight chance that hot water might tickle it as it is considered 'practically' insoluble in water and will dissolve alkaline aqueous solutions (but so, most likely, will the aluminium of the mast!).

Me, I would go for hot water, possibly followed by a freezing spray to crack the deposits off

 

[Norman_E]

My advice is not to use either WD40 or ACF50 until you have used boiling water. A tip I had from a very experienced professional was to add a bit of washing up liquid to the water to break the surface tension, as it allows the water to penetrate better. If the water works and frees the sheaves follow up with ACF50 (which IMHO is better than WD40), if it does not work try again, as the water treatment works best of all if you can leave the parts to soak, which is difficult with a mast head. Only if hot water with some washing up liquid does not do the trick after repeated applications should you resort to using penetrating fluids, though I would try using a blowlamp to heat the sheaves before that. The reason is that once you use WD40 or ACF50 you have applied a water repellent and made it much harder for hot water to work thereafter.

 

[ghostlymoron]

I have freed sheaves by washing with hot water, spraying with WD40 for several days and then working them back and forth with rope loop. Once some movement is established full rotation can soon be established by repeated 'exercising' - it takes some patience though. Also be careful with poking about with screwdrivers etc, it is easy to damage the pulley.
Are your sheaves rivetted to the mast? Mine were and you can't remove the pin with them in place.