06-04-2004, 08:16 PM
Recently, I installed a 231 cam with new p rods and dual springs. Today while sitting in traffic, I heard a knock and pulled the car over. The car was towed home. I prayed that it was not a thorwn rod while taking off the v covers. I found that a rocker arm bolt had broken clean in half where it meets the bolt hole.
How should I deal with this? Take it to a professional? Drill it out myself and retap? do I have to take out all the rocker arms when I do this? I have enough room to work on the broken bolt even with the rocker arm to head spacer. what size bolt should I use to replace the broken bolt if I tap the bolt hole? Should I replace all the rocker arm bolts?Is this a difficult repair? Suggestions would be greatly appreciated,
I torqued all bolts to spec and had loctite on the bolts. I rotated the cam after the bolts were installed and checked the bolts a second time.
The bolt holes were cleaned out before the bolts were installed, however the bolt that broke did not screw in as smoothly as the others now that I think about it.
06-04-2004, 08:29 PM
get a bolt remover kit, I used this on a thermostat bolt, and it works great. You drill a small hole in the broken end, then screw in a reverse threaded bolt/bit and it back that broken bolt out. Then you can retape the threads, etc. I bet it was just a weak bolt, shit happens like that.
ss rally red
06-04-2004, 08:30 PM
My first thought would be to try and extract the bolt put and use a replacement stock bolt. Hopefully you could catch part of the broken bolt and use a small punch/chiesel to spin it out of the hole, or use an easy out. It would be better than tapping to a larger size IMO.
06-04-2004, 08:41 PM
Or use a dremel and create a slot for a large flat head screwdriver and back it out.
06-05-2004, 09:26 AM
Or use a dremel and create a slot for a large flat head screwdriver and back it out. That always works, a rocker arm bolt isn't going to be bottomed out in the head, so when the bolt snaps it should release any stored torque. Slotting it should work or even trying to turn it with a drill with just a bit running in reverse might get it out enough so you can grab it.
Those screw extractors are really good things to have, until you break one off in a bolt and then have to drill a carbide extractor with a carbide bit, doesn't work that great.
06-05-2004, 11:40 AM
The loc-tite might make it a little more difficult. An extractor will probably get it out.
I had to heli-coil one of my rocker bolt holes, because the rocker bolt started to crossthread and the threads in the head got a little messed up. Didn't want to take any chances. I had never helicoiled before, and it was easy. (but I had the engine on a stand, so it was also easy to flip the engine over so no shavings would go inside too).
Hopefully you won't have to helicoil it, and can just get it out with an extractor, without having to fully drill it out.
06-05-2004, 12:37 PM
If your going to drill that bolt and use an easyout be ABSOLUTLELY sure your center punch mark is DEAD CENTER before you drill. As was mentioned the locktite is going to give you some added difficulty. The OEM GM bolts put the locktite under the built-in flatwashers instead of on the threads themselves so they don't pose this problem in the event a bolt breaks off. I'd first try the suggestion of making a flat slot with a dremmel tool and if that doesn't work try the screw extractor. The helicoil should be a last resort in the event you damage the threads while removing the broken bolt which hopefully won't happen. The fact that you had a warniing should be a lesson to other people working on their engines. Your screwing a steel fastener into aluminum. When you feel inordinante resistance during fastener installation it's time to STOP and get out the tap set and dress the threads before you procede. If you had done that when you felt that snag you may have avioded this problem
06-05-2004, 01:30 PM
I had somthin of this nature happen to me at work once i used a left hand drill bit and it worked wonderfully!!!!! I did have soem diffculty in gettin the bit to set center though
06-05-2004, 04:59 PM
When you feel inordinante resistance during fastener installation it's time to STOP and get out the tap set and dress the threads before you procede. If you had done that when you felt that snag you may have avioded this problem