how to remove stuck stainless bolts from aluminium stern drive housing

[badman]

yep, got some pretty tight bolts here.
Anyone got any ideas to free very tight or stuck bolts to avoid shearing?

I have noticed some of the threads on the bolts seem to have corroded with the thread seating in the housing and this has bulked out the thread.

Often the top half of the thread comes out but the bulked out lower part of the bolt gets tighter and then shears or causes damage etc.

Open to suggestions
thanks

 

[WizeOne]

Re: how to remove stuck stainless bolts from aluminium stern drive housing

Heat, penetrant, heat, penetrant, heat, penetrant. All of the aforementioned applied whilst both alternating your attempt to slightly tighten as well as slightly loosen.

It's going be be a one bolt at a time issue. Apply heat, on the casting, just short of burning the paint. When you get a little movement on the bolt, apply more penetrant. Keep working with all three techniques, ie, heat, penetrant, tighten and loosen. Patience will pay off.

Once you get the bolt out, clean the hole with an aerosol such as 'Brake Cleaner' then air pressure, then run a tap down the hole and clean again.

When re-assembling, use copious quantities of marine grease applied to the bolt threads.

 

[badman]

Re: how to remove stuck stainless bolts from aluminium stern drive housing

ok thanks for that.
i have taps, heating sources and grease and oils.
So you say heat the sasting not the bolt.... so the casting expands and releases tension off the bolt?

nice one... as we say here.

 

[WizeOne]

Re: how to remove stuck stainless bolts from aluminium stern drive housing

ok thanks for that.
i have taps, heating sources and grease and oils.
So you say heat the sasting not the bolt.... so the casting expands and releases tension off the bolt?

nice one... as we say here.

Yes, that is the idea. Heat and expand the casting. That alone will help break up the corrosion that is holding the bolt. However, you will want to do your tightening and loosening excercize when it is still hot as well as once it has cooled. You may need to do that thru several cycles before you start to get any movement on the bolt. Once you get it, leave the bolt at it's loosest then apply the penetrant and let it soak.

After soaking, try to rock the bolt again. Go as far as you can then start with the heat cycle again. Repeat all till you can back the bolt out. You can go around in a circle and go after all the bolts in succession.

 

[Mischief Managed]

Re: how to remove stuck stainless bolts from aluminium stern drive housing

A mixture of 1:1 acetone and automatic transmission fluid makes an excellent penetrating oil.

 

[badman]

Re: how to remove stuck stainless bolts from aluminium stern drive housing

A mixture of 1:1 acetone and automatic transmission fluid makes an excellent penetrating oil.

ta for that. will make some up tomorrow.