broken exhaust stud not cooperating

[oldgeek]

What sort of drill bit did you use to drill it out as far as you did? I am dealing with a nightmare bolt stuck in the left side of the engine, but all the bits I try seem to just dull.

I just use a good quality=price drill bit. The ones you get from the discount store are usually no good. I picked up some left handed drill bits from one of the chain auto stores around here, made for drilling bolts out, and they were total krap. They would not even nick the surface. I also prefer not using the "split point" type when drilling progressively larger holes, because their design causes them to bind, and break easily in that application.
Also make sure you use some form of fluid to cool, and lubricate as you drill. It also helps to vary your drill speed. Fast is usually not good, as it gets too hot and ruins the drill bit. I would say a medium to slow speed. Good Luck!

 

[Daddio]

Cobalt is a good material for hardened steel. Oldgeek nailed it: Oil to keep the bit cool, and a slow speed between 1650 - 1800 RPM is best. Look at the bits you tried. If the tip of the bit is a different color it got too hot and dulled on you.
A couple more suggestions:
Start with a small bit and work your way up and don't put too much pressure on the bit, that creates a lot of heat, let the bit do the work. Don't be afraid of a little heat either as mentioned earlier in this thread, it's called annealing (true annealing requires the bolt to get red hot). I wouldn't recommend true annealing which would probably ruin the case around the bolt first, rather some good heat and rapid cool should change the properties of the bolt enough to make it easier to drill.

Good luck.

 

[oldgeek]

I got good news, and i got bad news.

The good news is that my exhaust stud repair is complete. I got it tapped clean to 8mm, and found a good grade 8mm x 1.25 x 55mm long hex head bolt to go in the hole.I just cut the head off, and screwed it in. Done! (all before lunch! LOL)

The bad news is we had a minor kitchen fire (can fires be minor?)
We are so lucky! I walked in right after the wife and kids left, just in time. Another 60 seconds and it would have been tragic. An empty cardboard box that had contained cookie dough from the kids school got set on the stove, and the stove got knocked on somehow. I may post a picture later in my ABANDONED album , but for now i gotta go to SEARS to find a new hood for the stove, some paint, and something to fix the counter top. I hope they got one in the clearance room! LoL

 

[Shaun Chandler]

Good to hear you got it fixed. Sorry to hear about the kitchen fire but it sounds like you got lucky. I used to clean those fires up. My first job after high school was restoring houses after fire and flood. Good way to get your ass back into school.