Broke one of the bolts in my camshaft housing then made it worse.

Hi everyone. Would appreciate some perspective here. I have a 2010 Prius with about 203k miles and needed to fix my head gasket. I'm broke, the car is paid off, and I do have some car repair experience so even though I knew this was long shot I needed to fix it myself.

Everything went fairly well until I was torquing down the 17 gold camshaft housing bolts. I was following the manual - 20 ft/lbs and in torque sequence. Bolt 15 in the sequence broke. This stopped all forward progress and my hopes to get my car back on the road soon. My good friend and roommate has been helping me on this and told me this might be the worst thing that can happen. The bolt piece is lodged in good, haven't been able to spin it using something like a flathead screwdriver, and by my measurements, is possibly lodged exactly between the camshaft housing the the cylinder head, meaning if I untorqued the rest of the bolts and removed it, it may not come off without damaging the threads. I am also scared another bolt might break. I already spent everything I had on the parts, gasket, and getting the head machined.

We sat on the problem for almost 24 hours and he advised me not to do anything because we need to preserve the threads. While I agreed, I decided eventually to try to bore a hole in the nut and use an EZ out because I felt like I have no other option. I created a metal tube of stacked nuts that fit in the bolt hole and I was sure they would prevent the drill from touching the threads. Well of course - the drill slipped and I somehow hit the threads anyway.

I attached a blurry photo from the borescope - you'll see the suspicious dark spot where I'm certain I hit the threads. And of course, bored absolutely no hole into the bolt whatsoever.

At this point, I don't know what to do. I believe my options are to:

1. Keep attempting to extract this bolt (though I am feeling very discouraged here).

2. Disassemble the engine and go back to the machine shop, and hope they can fix the threads and extract the bolt. (I'm out of money though)

3. Push forward without this bolt, and hobble it to the nearest shady dealer to trade it for something, even a shitbox, so I can make it to work. (Live in a rural area, public transit is not an option, at least not until I get into town, which requires a car).

Any ideas?

 

Thanks so much Mendel.

Yes, it's about two inches deep into the hole.

It is pretty puzzling why it would snap, I agree. In theory there should be no debris as the head came straight from the machine shop, but I did not use any compressed air on the camshaft bolt holes, only on the head bolt holes. In the future I will be more careful about that, and I would pull the camshaft housing bolts out and inspect them before torquing. I left them in in the same way Gasket Masters and other Youtubers do when doing this job.

I've had another night to think about it and you're right, all I can do is continue working on this bolt. I need a good center punch from the hardware store or my drill will slip again. I'm just hoping my previous mess up didn't ruin the threads so bad that I can't extract this with the EZ out.

 

Thank you - this is the next plan. I couldn't find any left handed drill bits at the hardware store or the auto parts store so I've ordered a set.

Yes, lesson learned on always placing the divot.