Corroded Bolts in Aluminum

Ned120

Cadet
Joined
Aug 8, 2008
Messages
18
Has anyone mastered removing corroded bolts from aluminum housings? Particularly those below the water line (lower ends and waterpumps) are giving me fits.
 

Ned120

Cadet
Joined
Aug 8, 2008
Messages
18
Corroded Bolts in Aluminum

Has anyone mastered removing corroded bolts from aluminum housings? Particularly those below the water line (lower ends and waterpumps) are giving me fits.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: Corroded Bolts in Aluminum

After over 20 years as a full time outboard mechanic in a salt-water area, my answer is yes.....and no. I've removed a bazillion of them. And broken a bunch too.

The secret is heat. Hot, concentrated heat, like from an acetelyn torch. But you probably don't have one of those, so you will have to do the best you can with what you have. And break a lot of bolts.

Then you can develop the skill of drilling them out. But that's a different school.
 

asdasc

Senior Chief Petty Officer
Joined
Aug 28, 2008
Messages
680
Re: Corroded Bolts in Aluminum

I have tried it with a propane torch, with zero luck. I ended up buying another parts motor because I still haven't gotten that bolt out...

:confused:
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Corroded Bolts in Aluminum

I heat them up with a torch and then work them back and forth very slowly. Maybe just 1/8" back and forth at first. That has always worked for me.
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Corroded Bolts in Aluminum

And when you put the fasteners back, coat them with gasket cement or non-hardening Permatex.
 

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: Corroded Bolts in Aluminum

I use a blowtorch, and that works about half the time for me. For the other half, I have got very good at drilling them out over the years. :mad:
A center punch and a real set of cobalt drill bits makes it tolerable. A set with a left hand twist helps even more.
 

mthieme

Captain
Joined
Oct 6, 2007
Messages
3,270
Re: Corroded Bolts in Aluminum

Heat doesn't work every time.
I had two rear motor mount bolts on a Merc 402 that I had to drill and tap this season. Make sure your first bit is centered. If subsequent bits walk into the aluminum, you're done.
 

Grem

Seaman Apprentice
Joined
Oct 6, 2008
Messages
45
Re: Corroded Bolts in Aluminum

It's really best to concentrate the heat on the bolt. I have a microtorch which is ideal. Other people here who have a mig welder suggest tapping the rod on the bolt until it's hot, which sounds good to me.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Corroded Bolts in Aluminum

Duplicate post
 

Bear 45/70

Seaman
Joined
Nov 2, 2008
Messages
59
Re: Corroded Bolts in Aluminum

There is no magic. Steel in aluminm corrodes. Heat is best. But always be ready to drill out the ones that break, because some will, no matter what you do.
 

finlay

Cadet
Joined
Apr 22, 2007
Messages
26
Re: Corroded Bolts in Aluminum

Yeh there is no easy way..
Use heaps of heat, heaps of penetrating oil and work the bolt back and forward little bits at a time and also thought out the process of all this keep hitting the head of the bolt with a hammer, the shock of the impact loosens the built up corrosion around the bolt.... and if all else fails snap and drill and tap :)

another method i have had to use with the bolts on the sides of clamp brackets holding the trim pumps in is snapping them and then building the ends of the bolts up with weld (i did it with a stick welder due to and on site job :p ) mig is a lot easier..then welding a nut on the end of the built up weld... it works a treat no oxy heating required....
 

Ned120

Cadet
Joined
Aug 8, 2008
Messages
18
Re: Corroded Bolts in Aluminum

Thanks to all. I've got acetylene so will try heat. Due to placement of bolts there is no access to drill them accurately though I've been shown how. One bolt head snapped straight through the bolt head and will try the welding on of a similar sized nut to form a new head. Will hope to report the results as progress is made.
 

1946Zephyr

Vice Admiral
Joined
Oct 21, 2008
Messages
5,556
Re: Corroded Bolts in Aluminum

oh my...corroded bolts, huh? Yea, these can be quite the hassle. Getting enough heat on them, til they glow red, is the best method. There are times though, that they break, reguardless. If you end up breaking them, then it's good to have some sort of centering jig, that fits snugly over the bolt and a small center hole to get the drill bit perfectly centered. It's too easy to get off center and have a drill bit walk on you. Gawd...I hate that.
 

jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,174
Re: Corroded Bolts in Aluminum

oh my...corroded bolts, huh? Yea, these can be quite the hassle. Getting enough heat on them, til they glow red, is the best method. There are times though, that they break, reguardless. If you end up breaking them, then it's good to have some sort of centering jig, that fits snugly over the bolt and a small center hole to get the drill bit perfectly centered. It's too easy to get off center and have a drill bit walk on you. Gawd...I hate that.

I'm an amateur machinist but have learned the basics to avoid that.
Use a punch if at all possible, then you need a machinist's centering drill bit , they are designed for vertical mills. They always move the centerline of the drill bit towards the shank by design. Look like this,
http://www.drillspot.com/products/454957/Keo_30251_Spotting_Centering_Drill

You can't actually drill hole with it but it gives a 1/8" start. This bit will not wander around if properly started (punch). If used in a drill press or vert mill it will always follow the centerline of the spindle. So a steady hand(2 hands) is good. Trying to drill deeper than the shank width of the drill results in snapping the tip off in the metal, thats kinda bad.
Drills wander because the drill shaft is slim and bends under load, a center drill shaft is magnitudes thicker than the cutting tip.
Clean machining is all about rigidity.

Getting snapped bolts out is a snap with a low power welder.
If building up a weld in alum special care is needed to protect the alum, its simple with cast iron blocks.
Alum will distort or just melt if too aggresive an approach is used, let cool between welds, tap with hammer, remove slag and keep going. Most guys just grab the weld with locking pliers and many times the bolt is already loose from the heat anyway.
Steel bolts into alum blocks is ez, the corrosion is the elec resistence which the weld heat burns into ash, the bolt can often be removed by hand, no tool required. I use a mig, I talked to one guy who said he does half a doz engine blocks in 30 minutes and gets em all.
Says the ez outs are best if the bolt is already loose because torque is reduced as the ez out has to be smaller than the bolt dia anyway.
 

HybridMX6

Senior Chief Petty Officer
Joined
Oct 22, 2008
Messages
676
Re: Corroded Bolts in Aluminum

I have one that snapped off on me in the midsection. It's the one that is under the trim tab. I don't have a welder or equipment to do that, so my only option is a propane torch. I've tried grinding a slot into it with a dremel so I could try my impact driver, but it's not moving. So, what's ya'lls take on using the propane torch, since it's all I have? Just get it glowing red hot and try vice grips?
I have another one in the engine block all the way at the bottom, but it's got to come off anyways and go to the machine shop for some work, so I'll let them deal with that one.
 

Al-53

Chief Petty Officer
Joined
Jul 17, 2008
Messages
491
Re: Corroded Bolts in Aluminum

Can you replace the old bolts with Stainless ones..also would it be best to use never sieze on them also or would that cause problems with them loosening later on...

Also a old timer told me once..on stuck bolts..if you have a air impact gun..turn the air way down and just hit the bolt a few times..the lite impact sometimes loosens them..you just want it to tap it repeatedly..

Al
 

Bear 45/70

Seaman
Joined
Nov 2, 2008
Messages
59
Re: Corroded Bolts in Aluminum

Can you replace the old bolts with Stainless ones..also would it be best to use never sieze on them also or would that cause problems with them loosening later on...

Also a old timer told me once..on stuck bolts..if you have a air impact gun..turn the air way down and just hit the bolt a few times..the lite impact sometimes loosens them..you just want it to tap it repeatedly..

Al

The corrosion is cause by the dissimilar metals (aluminum and steel) and you will still get corrosion with stainless bolts. Heli-coils help but are expensive. Some anti-seize products have metal in them which just makes things worse. Use Sealer 1000 on the bolts, but for a saltwater motor, nothing is sure fire except using epoxy on the bolts and the wrong kind are as bad if not worse than the corrosion. Even a 3/8 drive air tool, turned down will break a bolt unless you are very careful.
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Corroded Bolts in Aluminum

The fasteners should already be SS ... I've never seen anything else.
 

HybridMX6

Senior Chief Petty Officer
Joined
Oct 22, 2008
Messages
676
Re: Corroded Bolts in Aluminum

Mine all are, but they still snap. I've got to finish pulling the powerhead off tomorrow, so I'll try the torch on the snapped bolt in the midsection and post how it goes, or doesn't. Wish I had welding equipment/experience.
 
Top