tda1

Turns out jpitman2 was correct...there are 14 bolts total. One is hidden under the center lip of the WP and recessed. Not visible from any angle.
What a waste of an entire day
We managed to get it off but now have to tap and rethread that hole to get a screw back in because the one that broke off is goes all the way to the water dam on the back side. (of course that would be the one).
While drilling it out, one of the tips broke off in the hole and now is preventing further drilling. The fun continues......

danglerb

Timesert preferred fix to drill and tap.

MFranke

This has worked for me: Get yourself a few left hand/reverse hss bits, use a blue flame to heat and let it cool, then go slow with drill and use oil. You may be able to spin it out early.

fraggle

Not enough is left, and the bit that broke in there is tough. No fun on this one. Damn you 14th bolt!!!

tda1

I got several colbalt bits...so going to give it another try tonight. also got new bolts for all 14 holes

Bill Ball

If you break a cobalt drill bit off inside the block, you will be close to what I encountered in my first timing belt job when I managed to snap off a tungsten carbide tap in one of those holes that I had drilled. Tungsten carbide is harder than cobalt steel. What worked for me to get that tap out was diamond tipped Dremel bits, as in Dremel 7150.
http://www.toolup.com/dremel_7150_di...FSzhQgodiVMA8A

Used in short bursts (10-15 seconds of moderate pressure, then let cool for 20-30 seconds), these small bits made quick work of the tap as I cut across it in a few minutes and the pieces fell out. I only needed two of these bits - the first lost its tip from overheating. You may want to go right to that solution. It should be easy with your softer drill bit piece.

After you get the remnant out, if the original threads are destroyed, the best solution is Time-Serts. Heli-Coil, which is more readily available (sold at Autozone) would be plenty strong enough for these very low torque bolts, but may not provide the seal needed, as you said this hole penetrates the water jacket (I didn't know any of the WP bolt holes did that). The 6mm Time Sert kits are expensive.


NOTE: The reason my tap broke was that I had drilled the bolt slightly off-center, leaving a small crescent of the original bolt in the hole. That steel piece caught the tap and snapped it. Be sure you are not in the same situation, as that may snap the Time-Sert or Heli-coil tap.

SECOND NOTE: I have both Heli-Coil and Time-Sert 6mm repair kits. I can Priority Mail it to you for you to borrow for postage cost (~$5) if you need either. (Actually, I need to check that later today - I may no longer have the Time-Sert kit)

Jerry Feather

I think there is a kind of tool that you can obtain at the machine shop supply, whereever, that you can use by driving some thin fingers down the chip reliefs on the broken drill bit and then turn it counter clockwise, like with an easy out, and hopefully get the piece of drill bit out. I can't say off hand where you can get one of them, and now that I have written this I have to wonder is I was dreaming about this and maybe it is something that I invented in my sleep. Anyway, have a look for something like that. If I can think of where I have seen those I'll post again.

Jerry Feather

Now that I think about it some more, you may even fashion something yourself with some piano wire, or other very hard thin wire, the largest size you can get into the two drill bit chip channels and drive them in as far as they will go, then try to twist the bit out with something like vice grips. Just another thought. I think all you will need to do is break the bit fragment loose from what it is stuck on now and then it should come out pretty easily.

Maybe you can google something like broken drill bit removal, or such.

fraggle

Unfortunately - or fortunately? - it seems only a shard of the bit broke off. That shard does a great job munching on "normal" bits, which is all we had as backup.

tda1

the colbalt tips don't seem to be making a difference but they aren't breaking but they aren't doing the job.

Bill Ball

As I noted above, Dremel with diamond tipped bit. Cheap and effective. And don't think that Harbor Freight's similar looking supposed diamond-tipped bits will do the job. They won't.

Also, how good are these "cobalt-tipped" bits? If they are Harbor Freight, then no wonder they are failing to do much.

With the Dremel idea, which worked well for me, you have to be a bit careful and develop a technique that will hole out or cut across and release the stuck fragment w/o gouging the wall too badly. If you go to Time-Sert, there is some leeway with gouges. As a final saving grace if you do botch this, Time-Sert makes the much thicker walled Big-Sert. Overkill in terms of strength but a perfect solution if you really mess up the hole in the block.

There may be other solutions that are easier, but none come to mind at the moment.

Leon Speed

You really need a hardened steel left turning drill bit. These are specialty items for metal workshops and costly. Remember to reverse the drill rotation as well

jeff spahn

Time Serts are the answer after you get the pieces out. My block has many of them.

tda1

Yea Jeff...several have suggested them. I ordered some and they will be here tomorrow. I'm taking a breather from the car for a day or so to prevent a sledge intervention

RET

I think that the tool that Jerry referenced is a broken tap extractor. You might search for that or "broken tap remover". A two flute remover might let the broken drill bit be "unscrewed" from the hole.