Stainless Bolt Seized in Aluminum

[Pete]

Trying to dismantle a Marquipt Sea Stair boarding ladder that has been together for 33 years. The old 5/16" stainless machine bolts are threaded into aluminum and are cold welded, or seized, or whatever, they just do not move. Now that I have rung one off, I decided to ask if there are any suggestion on how to get the bolts out in one piece. Help would be appreciated.

Pete

[MikeP]

Spray some of your favorite penetrating stuff on there and let it sit for a bit. In my 40+ years of automotive engine work I never found any of the various products to work noticeably better or worse than any other and that includes old standbys like Liquid wrench, WD40 and Marvel Mystery Oil as well as "hi tech" stuff like PB blaster, Kroil, etc. Pick the one you have handy and don't bother buying one of the others thinking there is some magic there. There is no magic!

Then attempt to TIGHTEN the bolt. That's right tighten it - the tiniest fraction of a turn is sufficient and it will break the seize much easier and with far less risk of snapping the bolt than trying to loosen it first. THEN loosen it a bit. If it binds up, tighten it again and then loosen it - it will turn a bit more this time Tighten it again, loosen a bit more, etc etc etc. This will usually do the job though it may take a lot of tightening/loosening to unscrew it completely without damage.

If you are unable to succeed in the first step - slight tightening - then apply some heat with a propane torch to the AL - yes, the penetrating oil will light up! If THIS doesn't do it then just give it up and use a nut breaker, knock put the bolts and use new ones. Frankly this is the easiest and by far the fastest method in most cases!

[Pete]

Mike, need a little with your second to last second where you write, ....use a nut breaker, knock put the bolts and use new ones. Do not know what "knock put" the bolts means. I think I am about their with some of these that have resisted PB blaster, heat, tighten/loosen, hammer to the head, etc. I can not believe how easy it is to twist these 5/16" stainless bolts in two.

Pete

[kwerges]

Without hijacking the thread, I have the same problem (stainless screw through aluminum) in a fighting chair I am rehabing. Problem is, the screw then goes into wood, so lighting off the PB Blaster is not an option. I'll be very interested in the responses as well...

[Glory]

Use heat, heat the aluminum as fast as possible and turn the bolt, if it squeks heat more.

JM

[mike]

Also try hitting the bolt with a ball peen hammer; a few sharp raps will some times break the corrossion loose and allow you to wrench the bolts back and forth as already suggested by others. Heat, hammer and liquid penetrating agent in various amounts and sequences; after that it's drill and re-tap and or Heli-coil. Good luck.

[Genesis]

Heat and penetrating oil.

Aluminum and Stainless wind up effectively "cold welded" due to galvanic corrosion. Lots of penetrating oil and take your time - soak it good, wait, soak it again, wait, soak it again.

Then heat the ALUMINUM as quickly as you're able (aluminum expands more than stainless when heated) and attempt to tighten it to see if you can break it free.

If you fail at the first attempt more soaking is in order.

I can usually get this sort of thing apart if I am patient. The problem with being impatient and breaking it off is that it is hell to drill out stainless in an aluminum plate!