How to remove seized bolts on aluminum?

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nnam

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I was doing a transmission oil change, and I broke 3 bolts so far. I was very careful, but I didn't believe penetrating oil would work, or if I would have time to wait for them to penetrate.

So after 3 broken bolts, I am ready to accept being wrong, and hopefully there is some penetrating oil that would work helping me remove the rest of the bolts, and figure out how to drill the other bolts out.

Is there a penetrating oil that would work with steel bolt on aluminum?

I may try again, with a hammer hitting the bolt head a few time before removing them, but I think I need some help.

Also, any tip on how to drill these out? I think alignment is the hardest. Since it's 10mm socket sized bolt, it's very small, and I don't know if tiny bolt extractor will be able to remove them. The other option would be larger bolt, or using inserts.
 
One thing that I can testify to is that screw extractor will not remove a bolt that has been twisted off, without itself breaking and creating a much larger problem. Accurately center punch the bolts and drill them out. Penetrating oil is next to useless in your situation, as you sugghested it may help to give the remaining bolts several good sharp raps with a punch and hammer.
 
I would use heat. You're likely dealing with bi-metallic (galvanic? I never remember which is which...) between the aluminum and the steel bolts. Penetrating oil does nothing for that, so your only solution is to find some way to break that. Smacking the head of the bolt a few times with a hammer can help, as can doing a small 'tightening' turn before loosening it.

However, the best way is to hit it with heat. The aluminum case itself is going to expand significantly faster than the bolt, so that can break up the corrosion enough to unbolt it. I've had luck doing this in order to use an extractor in the past (as benychree says, if the bolt is 'stuck' enough to break the head, an extractor wont do anything, but if you can fix the reason it is stuck first....).

One thing to note that is very important: IF You choose to drill them out, make absolutely sure you're centered and keep the drill straight. If you start drilling and hit the aluminum, the bit can often wonder off-center into the aluminum, destroying the case.
 
You can try a mixture of acetone, ATF, and kerosene in even parts, sprayed liberally over the entire area. Do that for a few days if possible.
Use an impact driver with a hammer to coax the bolts out.
For the broken ones, use an 1/8” cobalt drill and center drill the hole (you could make a taper tip bushing to ensure you are on center) Drill to 4.5mm.
Run a M6x1.0 gun tap through the hole and you are done
 
It would help if You could make a strap of metal with a starting hole in it, and have a bolt hole in the other end that goes to a near by bolt hole. Align the hole on top of the broken off bolt and it would help keep the drill bit centered. If You have room for it.
 
I had the same problem with 1/4-20 bolts holding water jacket covers on outboard motors. Aluminum in contact with steel oxidizes to aluminum oxidizes in the presence of salt water at the interface which effectively destroys any clearance and locks the fastener in. Removing the bolts was a gamble. As I recall, about half of them snapped. When trying to remove the fastener, a gentle back and forth motion of the wrench can break the bond to the steel. Don't force it to the point of twisting the fastener as breaking it would then be inevitable. Heat should help

As to the snapped bolts, I drilled them out and drilled and tapped the holes for 3/8-24 x 1/4-20 inserts that I made from threaded rod. I seated them with epoxy and ran a tap in to remove any epoxy that might have made its way into the threads. Even if I managed to successfully drill out the broken bolt, I figured that the corrosion would have weakened the threads anyway. Helicoils should work for you.

My task was easier than yours. At least, I could work standing up. Trying to drill a centered hole while lying on a creeper would be a daunting task. Even if you have the use of a lift, it will be difficult.
 
Okay, all good advice above. Are you trying to do this while laying on your back?

If so, try to borrow a friends hoist so you have plenty of room to work. I've changed my 7.3L diesel oil cooler while laying on my back in a northern Michigan winter, more space should help....
 
benmychree said:
One thing that I can testify to is that screw extractor will not remove a bolt that has been twisted off, without itself breaking and creating a much larger problem. Accurately center punch the bolts and drill them out. Penetrating oil is next to useless in your situation, as you sugghested it may help to give the remaining bolts several good sharp raps with a punch and hammer.
Click to expand...

Great, thanks all. With your help, I felt a bit more confident, or rather knowing not much else to do. I rapped each remaining bolt with a hammer several times each, and with a hammer driver, I took them all out, except the broken one. I was trying to be careful to do it by hand.

I feel like an idiot right now. Now to the extraction part ...

Thanks all again!!!
 
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