Welding or Brazing?

[BigD_83]

I have a valve cover bolt needing removal. There are just enough threads (1-1/2) sticking out that that I can turn a nut onto the end and it firmly seats against the head,leaving a depression in the centre of the nut, over top of the sheared off bolt.

This is something that I have been meaning to deal with since I got this bike. I have no idea why it is sheared off, as it came to me this way.

Question: Would brazing be strong enough to join the nut and bolt for removal, or is welding still the way to go?

[Nessism]

Brazing requires a lot of heat. I think if you tried to heat the nub the surrounding aluminium would draw all the heat away. I'd weld.

[chuck hahn]

Depends on what clearance you have to get at the bolt!!! Either will work really. The heat from both will also crack the corrosion thats holding the bolt in. If you can get a MIG welder in, then start on the bolt and swirl outward till the nut is welded on. If a torch, then heat it up and drizzle the rod in and then flow it out to the nut. But be very carefull with a torch...aluminum melts at around 750 degrees!!! Do it quick and youll probably be ok. Let it cool a bit and put a few drops of old engine oil on it to soak in...the heat will draw the oil down in to the hole.

[GregT]

I wouldn't bother with the nut - I usually TIG or MIG a bolt onto the end of the broken piece. The heat of the weld usually breaks the piece loose and the extra length of the bolt gives any required leverage.
Electric welding is better here than gas IMO as it's a shorter, more localised heat time/area.

[chuck hahn]

Greg the thing with a nut is that now you also have a head for a wrench or socket to remove the broken stud the rest of the way.

[BigD_83]

I wouldn't bother with the nut - I usually TIG or MIG a bolt onto the end of the broken piece. The heat of the weld usually breaks the piece loose and the extra length of the bolt gives any required leverage.
Electric welding is better here than gas IMO as it's a shorter, more localised heat time/area.

GregT:

A straight bolt onto the end of the sheared one wouldn't increase torque, so I can't visualise what you are saying about increasing leverage.

If the added length provided more clearance, then I could get a longer tool on the bolt, thus providing more leverage.

Can you clarify what you mean?

[bccap]

Did somebody get a welder for Christmas ?

[BigD_83]

I was leaning toward brazing as the tools are more readily available to me, but Ed's thoughts and Chuck's description of the process has scared the bejeeber's out of me. I'm not sure I'm willing to take on the prospect of melting/warping the aluminum.

[BigD_83]

Did somebody get a welder for Christmas ?

No, but you know I've been looking for the best deal for a long time

[tom203]

IF you got engine out of frame, I'd use left hand drill bit- use pointy nail set to make depression in center of stub.

[chuck hahn]

I was referring to the torch that will get it hot real fast.. MIG will get the bolt hot but wont transfer very much to the aluminum..like a flame will do.

[tkent02]

I was leaning toward brazing as the tools are more readily available to me, but Ed's thoughts and Chuck's description of the process has scared the bejeeber's out of me. I'm not sure I'm willing to take on the prospect of melting/warping the aluminum.

You get the bolt super hot and it expands, which crushes or cracks the corrosion. The aluminum in contact with the hot bolt then gets hot and expands, so the threads loosen up. You don't need to heat the aluminum directly. It shouldn't melt or warp anything. Oil soaks in and makes it easy to move the loosened bolt, someone on here posted that wax will suck itself into the threads ands work wonders, planning on trying it next week on the 550 head.

[BigD_83]

IF you got engine out of frame, I'd use left hand drill bit- use pointy nail set to make depression in center of stub.

In frame at the moment Tom. Not looking forward to the frame-up resto, but that's at least a year away.

[chuck hahn]

Youll be fine Big D...just weld the nut on and turn it out. The flame on a torch tends to spread when it hits the nut is all i was getting at. MIG gets the exact area the wire contacts molten so the filler wire will join the 2 pieces..very localised and controlable.

[BigD_83]

I was referring to the torch that will get it hot real fast.. MIG will get the bolt hot but wont transfer very much to the aluminum..like a flame will do.

Yup, I follow you, Chuck.

Brazing seems straight forward, but having the right tip shape, heat setup, and swirl technique might make it more difficult for a newbie than MIG/flux core.

Speaking of flux core: I obviously want to keep molten metal out of the cam/valve area when doing this. How much does one have to worry about splatter? I guess it would be prudent to shield the area somehow?