Engine hard to turn, advice before I proceed

[errorcauser]

I thought so, I guess 6mm, or 6mm and change. Worried a bit about staying straight with no drill press (and not wanting to pull head even if I had one), but gonna go for it.

Get it as close to center as possible starting with a smaller bit. Then work your way up, this way you can maybe straighten it up some as you go up if you get crooked.

The hole has to be large enough to get your tap in, but not so big that the tap can't cut threads. It can't be to small, else you'll have a hard time getting the tap in there. Even using the recommended size bit for the tap I bought, I was worried that I was going to snap the tap off in the hole.

Keep the hole oiled good and take your time. After I got the tap started pretty good, I would back it out just a little and then go forward. I wouldn't back it all they way out, because I'm sure when you tried to start it back in it would cut different threads (make a mess).

[twiggy2cents]

rather than trashing it get some reverse drill bits and a center punch, center punch the screw and then pick the appropriate size probably the smallest. Drill in reverse. The key is to go slow so it will grab a bit and try to unscrew it

[psyguy]

rather than trashing it get some reverse drill bits and a center punch, center punch the screw and then pick the appropriate size probably the smallest. Drill in reverse. The key is to go slow so it will grab a bit and try to unscrew it

ditto!

no need to go for an insert just yet. if the bolt is M6 i'd use a reverse drill size 2.5mm or 3mm for a start. the drill depth you can gauge by looking at other similar bolts. if the bolt doesnt come out while drilling, you can go up a size on the drill bit or try bolt-extractor (ezy-out).

[doctorgonzo]

Thanks guys, Ed gave the same advice. This thing is gonna be back on the road someday.... I hope....

On a side note I was torqueing correctly, and at 7.3 lbs I can't believe I broke one. I'm a bit concerned now that they are brittle from heating and cooling, though engine temps wouldn't seem hot enough to do that.

[gearhead13]

Trying to drill out a hard steel bolt in soft aluminum is asking for trouble. I always err on the lighter side of torque when going into aluminum.

[doctorgonzo]

Trying to drill out a hard steel bolt in soft aluminum is asking for trouble. I always err on the lighter side of torque when going into aluminum.

Indeed, I might err on the side of a little loose when I put them back on.

[1948man]

Some PB Blaster sprayed on the bolt while you're getting all the drill bits, extracters, etc rounded up might make it a little easier to get out. I sprayed my exhaust bolts every day or so while I was waiting for my 4 into 1 pipes and those bolts came out real easy.