Seized SS bolt in Alu casting

[johnneale]

The stainless steel clamp bolts for my outboard are seized solid in the aluminium alloy bracket.
Normal method of a big spanner and lots of wd40 have failed to even nudge it.
Has anybody got a better idea. ????

 

[Norman_E]

That is because WD40 is the wrong stuff to use. What happens when SS bolts are screwed into aluminium alloy is that corrosion of the alloy produces corrosion products of greater volume than the parent metal, which seizes up the bolt. They are not susceptible to being shifted with penetrating oil. They are however water soluble, so boiling water with a dash of washing up liquid to break the surface tension may do the trick, especially if you can immerse the part overnight.

If that does not work heating the casting with a blowlamp should, but you have to be very careful with an outboard because of the petrol.

I recently bought some stuff called ACF50, which has good things said abouts its abilities as a penetrating fluid, but have not tried it on the stainless steel in light alloy problem.

 

[steve28]

blowtorch will work well but be prepared to touch up the paintwork on the bracket. Its worth taking the tilting bolt out so you have the complete clampstock only to work on.
I have unseized many over the years worst case had to be drilled out but that was only because customer had bent the whole threaded section inside the casting.

heat the alloy not the screw

 

[piperdog]

make sure when you replace them you give screws a luight coating of silicone. This will prevent future problems when you try to take screws out.

 

[steve28]

neat 2 stroke oil works well for the season as well

 

[noelex]

As well as the above suggestions try a longer lever. Put a long pipe over the end of a ring spanner or socket. An impact wrench can sometimes work as well if you can get a socket for it.

 

[tabernacleman]

tap,tap,tap with very light hammer/socket ext bar may take several hours/ days -dismantled my windlass over three days by tap-tap : oil;-oil

 

[noname]

Try diesel fuel,red or white.I have unseized allsorts with it from engines to bolts.
Dont be impatient if you can leave it soaking for a week the longer the better.
good luck !

 

[lw395]

Generally, heat is what you need. A hot air gun saves using up gas cartridges, but is still dangerous around petrol. Maybe start by running a kettle of hot water over it, at least this removes the salt!
If you can get the bolt head in the vice and twist the casting while heating that helps as the vice takes heat out of the bolt as well as holding it firmly. Diesel or any old oil applied while the ali is hot will help. I use neversease or similar metallic grease as a preventative. It's easier to repaint after torching the paint than get the threads helicoiled after stripping them, so lots of heat and not too brutal on the tools!
Good luck and take care!

 

[Topcat47]

Clean the threads first. Then apply heat (boiling water is safest). If this doesn't work, apply penetrating oil, leave for an hour or so and repeat the heat and torque. Sometimes you only get a half turn or so, but working the clean thread back and forth will eventually do the trick.

 

[dockmaster]

Try drain cleaner (acid)

 

[Guest]

Remove the clamp assembly and cycle it back and forth between the freezer and a medium temp oven. Eventually the corrosion will free up.

 

[Alfie168]

Both my Grandads were engineers. One on a White Star liner, the other on printing presses. They both had the same motto for shifting seized bolts/nuts

"Little knocks will move great rocks, where bigger knocks will break them"

So heat/cool/lube...gently try and shift with spanner..then heat/cool /lube..and gently try and shift with spanner etc etc.

It takes longer, but you get most things out undamaged in the end. I've used the method on seized bits on alloy engine blocks/cylinder heads and it does work.

Tim