You do the old wiggle-waggle, huh Hub? Good tip.
Yeah Rook, I shoulda looked. No circle L next to the bolt's circle designation. Chapter 9 first few pages shows the blowouts, next page shows the balancer blowout and no Locker for either balancer shaft bolts. Also, only by removing the top cover knows it's closed. I think it's more a closed casting so you can bust thru the bolt and not make a hole in the case... you still have the dome's distance, thus shim the drill bit. If the hole was exposed to the internals, no locker, and no leak... has to be closed, right?
"no circle L" = service manual does not specify thread locking agent. No thread locking agent was supposed to be used in factory assembly (but sometimes they do even when the book says don't).
"only by removing the top cover knows it's closed."
You would need to remove the engine above the balance shaft to look down in to see if the bolthole goes all the wat through the case. I don't know that there is a top cover on this part of the motor. You might have to split the whole case apart in however many pieces it is.
"I think it's more a closed casting so you can bust thru the bolt and not make a hole in the case."
The bolt hole is drilled in a raised portion of the case. The hole probably has a bottom so it does not open a hole to the outside when the bolt is removed. If that's an M8 x 10 mm hex head bolt, don't drill deeper than 10 mm. I'd probably go 9 mm just to be safe. Washers on the drill bit can be used to make a stopper that exposes 9 mm of bit. ...or just a piece of tape but stop BEFORE the tape touches the surface, not when. Tape can slip and it's not real precise since it can get hot and pushed up the bit--now you have a 10.5 mm marker instead of a 9 mm marker.
I would use a drill guide on this. I think you'll find one that will fit right on that machined surface around the bolthole especially if you can pull the shaft all the way out. Carefully center punch it and definitely start with a small bit and work your way up. You might even want to use a drill guide every step. If it's off center, the only thing I can see is needle file it centered the best you can. You do not want to cut into the female threads in the bolt hole. I wouldn't attempt this without drill guides. It's not a very long bolt but I believe you will need to cut at least a 6mm hole down the center of an 8 mm bolt. Not much margin for the drill not being perpendicular.
"you still have the dome's distance, thus shim the drill bit. "
You still have the height of the bolt head to consider when drilling. The head is no longer there so don't drill deeper than the length of the threaded portion of the bolt.
"If the hole was exposed to the internals, no locker, and no leak... has to be closed, right?"
If the hole went all the way through the case, it would leak oil especially if it had no thread locking agent to seal the threads. If this bolt went all the way through, the SM would at least spec thread locking agent to seal the threads from leaking oil.
I'd still consider the machine shop. Get a quote, see how it figures with the cost of the tools you will need to buy and the time. I would not rush it. Possibly a couple weeks if you have to work too. If you are a perfectionist, you can do it and you will know it was done right. If not, machinist I say.
I'm glad you brought this up MistZX14. I was planning to go with balancing shaft blanks someday....I think that is the part we are looking at. Thought there was two of them.
* Last updated by: Rook on 9/8/2020 @ 8:00 PM *
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