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!

 

[krush]

My buddy that removes more frozen bolts in a day then everybody here in a year combined swears by Kroil. Do that and add heat.

I usually oil it, heat it, oil it, heat it, oil, heat, etc if it is really bad. Let it expand/contract to break free.

Stainless on stainless machine thread (galling) and stainless/aluminum should always be joined with anti-sieze.

 

[yachtsmanbill]

Shock treatment usually works.... Chemical shock (Kroil) Thermal shock (heat) and IMPACT shock (duh)... the hammer rap will help, but anyone here ever work on a Jap bike? A hand held impact driver does well if you can get at the fastener. I like the 18 volt cordless impact wrenches for this too... easy to control; a little zing back and forth with some kroil or PB and its good to go... absolutely agree with the engineer trainee here... USE NEVER SIEZE/ ws

 

[MikeP]

When I say "knock out the bolt" I'm saying that you first break the nut with a nut breaker and then knock out the bolt from the "nut side" with a hammer and drift. Obviously there may be access issues with this, depending on the design of the parts and the location, of the bolt. But if the nut is broken you can usually turn the remainder of the bolt with a wrench and once it turns you can get it out.

A good friend that owned a (primarily truck) repair shop in Memphis never even bothered to fool with seized fasteners if he could get a nut breaker on them. He just immediately put the breaker on them and used new fasteners. What would take sometimes hours or days to do trying to coax a nut/bolt apart is done in less than a minute.

 

[Diver Down]

DIY Boater recommends soaking the area in a mixture of aluminum tapping liquid and SiliKroil penetrating solvent.

 

[luckydave215]

As one who has removed hundreds (maybe thousands by now) of galvanically frozen SS bolts from aluminum, bronze, stainless, and titanium parts over the 32 years I've worked at the Scripps Institution of Oceanography machine shop, I have some expertise in this area.
As mentioned by others, oil, low heat, and shock sometimes works. But not usually. And it usually destroys the part you're trying to save.
There's another way.......
If applying heat with a flame torch, heat the FASTENER (if it's sticking out of the parent part) instead of the parent aluminum. Heat it fast, and heat it yellow hot. The idea is to soften the fastener at a time when It's too big (from thermal expansion) for the (still cold) hole it's in. This is easier than you think as the oxide layer between the parts is a thermal insulator. When the fastener turns butter soft from the heat it plastically deforms to a smaller size, and the heat/cool cycle also breaks up the molecular bond between the fastener and the threaded hole. While the part is still hot (but not glowing) apply Moly-Dee tapping fluid to the threads. Use real Moly-Dee, accept no substitutes! If the first attempt is not successful, Moly-Dee may be completely washed out of the work area with acetone, most cutting fluids can not be removed easily, if at all.
The heat will cause the Moly-Dee to rapidly "wick" down the threads, and it's presence will prevent galling the softened threads during removal. After cooling, the fastener can usually be simply spun out with your fingers.
The BEST way to remove galvanically frozen fasteners is to find someone who is an artist with a tig welder. Have him weld up a "handle" out of droplets on top of the fastener making sure to heat the fastener yellow hot in the process. This works on fasteners broken flush, or even below the surface. I've removed plenty of microscope sized fasteners this way.
It is also the only civilized way to pull blind pins out of holes. For pins weld a small slide hammer to the end of the pin.
Taps broken in holes usually split along the long axis, make sure to weld all the pieces together before adding handle droplets so they don't "wedge" against each other during removal.
Follow with Moly-Dee as above