So I'm working on the timing cover and the intake manifold gaskets on my Suburban, and since last week I got into a jam regarding one of the new bolts to the new timing cover breaking off due to being overtightened. I was trying to do the torquing to spec, which is supposed to be 106 in/lbs., but it turns out the torque specs may have been too much. That or the bolts themselves weren't up to par to handle the torque specs. Anyway, 4 of the bolts broke inside the block while I was tightening (and unfortunately I didn't figure that out on the first one I broke
) and I was able to get out 3 of them by kind of unscrewing them out with an awe. The last one was coming out, but then it became difficult as it became flush with the screw hole, and then it became hard to spin it out with the awe, and I believe it's because I can't get a good angle on it with the PS pump bracket in the way. I also did try drilling it out, but all it really does is just scrape away the bolt, and not exactly drill through it. I don't know if my drills aren't fast enough, or if the bits aren't hard enough against the bolt.
With that being said, my next plan was to get some cold chisels and then kind of crack the bolt free. Is this an okay idea, or should I do something else? And if it's possible, I was wondering if anyone could tell me what the material of the timing cover bolts are. I got the Dorman timing cover number 635-505. Maybe I should get harder drill bits too?
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Okay, a lot going on here but Ill give it a shot.
Torque matters on main bearings and rod bearings and heads and intakes
Things internal to the function of the engine.
Torque doesnt really matter so much when you put in the "tin"
The front cover, the oil pan, the valve covers etc...
That is much more about having those surfaces clean and flat and straight.
A factory torque spec is exactly that.
It is a from the factory torque spec that comes from the line and is based upon in house inspected and calibrated and certified torque wrenches.
Most people do not have acess to those tools.
And, just a general rule of thumb.
The smaller the fastener, the smaller the tool.
Look at the diameter of the bolt.
And use the extension that is closest to that diameter.
You can only
And start with that.
My recipe for drilling out a broken fastener.
Start with a spring loaded center punch
Also know as an automatic center punch.
Eyeball that punch as close to dead nuts center as you can and pop it.
It makes a very small divot.
Look at it again.
If it is a bit off center, angle that punch and pop it again.
You are just chasing that metal back to center.
When you are happy with your center.
Bang that auto punch a few times to set that divot as the one you are going to chase.
Now you take a hard steel punch and establish that dent as a a landing spot for the drill.
Start with a really high quality high speed steel bit.
An HSS bit.
And then it is all about feeds and speeds and keeping it centered and cooled.
The goal is to drill dead nuts straight through the minor diameter of the thread and leave the major diameter stuck so you can chase it out with a thread chaser or a tap.
Whatever you do, dont try any kind of an "easy out" or any other miracle tool on it.
The only thing worse than a broken bolt is a broken bolt with a chunk of heated O2 tool stuck in it.
Get a couple of really good drills, Center those drills .
Keep them cooled while you drill with something
Even wd40 will work.
Low and slow and steady.
If you go full throttle crazy, you super heat the end of the bit and it doesnt cut anymore.
That heated end of the bit hardens the spot you are trying to cut.
And burns the drill.
So now you need a harder bit to cut through that.
But, the harder the bit, the more brittle it is.
And the the more brittle the tool, the faster it snaps off from a side load.
And that is my personal and opionated history of the "Heiicoil"