should I pin the crankshaft?
09-24-2006, 12:45 PM
#1
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should I pin the crankshaft? I just put in a new crankshaft bolt, and it came out within 1 hour of driving. The pulley walked a bit and caused my A/C belt to try jumping a groove, and the A/C tensioner was pushing it back on track. The noise indicated the problem, and I got lucky with no damage. 
I torqued it like this:
Use old bolt to hit 240 #
Remove old bolt, put new bolt on at 37 #
Mark the bolt and pulley with chalk, tighten new bolt for 140 degrees
I did not loctite, other than that I can't figure out why it came out so fast. It was suggested that I pin the crank, get a new bolt and put in the same way, but with loctite. Your thoughts?
I torqued it like this:
Use old bolt to hit 240 #
Remove old bolt, put new bolt on at 37 #
Mark the bolt and pulley with chalk, tighten new bolt for 140 degrees
I did not loctite, other than that I can't figure out why it came out so fast. It was suggested that I pin the crank, get a new bolt and put in the same way, but with loctite. Your thoughts?
09-24-2006, 02:21 PM
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If you have the tools to pin it, then pin it. If not torque it back to 240 with the old bolt... Take it out and blue loctite the bolt and just torque to 240-250 and click it a couple of times. Then have a beer! 
09-24-2006, 03:27 PM
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Originally Posted by SLED28
Ya big hands!! Call your biggest buddies over 
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09-24-2006, 04:36 PM
#8
The bolt is not tightened to a torque value, it is tightened to a specified number of degrees of rotation to achieve the correct bolt stretch. Measuring torque is futile and will not result in the correct preload because the torque measurement is highly dependent on friction. That is why GM does this by rotation, it provides more consistent bolt stretch.
If you re-used your old balancer, the required interference fit may have been compromised and that is the reason it spun off. Pinning the balancer will prevent this from happening.
If you re-used your old balancer, the required interference fit may have been compromised and that is the reason it spun off. Pinning the balancer will prevent this from happening.
09-27-2006, 12:08 PM
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Just for FYI, I decided to try the suggestion from SLED. I re-torqued the old bolt and smothered it with blue loc-tite. I know it's torque to yield, but there is a chance I did not get full yield the first time. So I marked with chalk and twisted it to nearly 5 o'clock, where I maybe went to 4 o'clock the first time and used no loctite. Then proceeded to have many beers. That steering rack is a PITA with turbo plumbing. 
So far with 100 miles on it and everything is good! woohoo
Thanks
So far with 100 miles on it and everything is good! woohoo
Thanks
09-27-2006, 04:18 PM
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Originally Posted by Chris Stewart
Just for FYI, I decided to try the suggestion from SLED. I re-torqued the old bolt and smothered it with blue loc-tite. I know it's torque to yield, but there is a chance I did not get full yield the first time. So I marked with chalk and twisted it to nearly 5 o'clock, where I maybe went to 4 o'clock the first time and used no loctite. Then proceeded to have many beers. That steering rack is a PITA with turbo plumbing.
So far with 100 miles on it and everything is good! woohoo
Thanks
So far with 100 miles on it and everything is good! woohoo
Thanks
You can re-use the bolt, but they are like 5 bucks, so its worth just buying one from GM.
09-27-2006, 04:49 PM
#12
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like he said. yeah you can reuse it, i know of guys who reuse the main and head bolts also. but for 5 bucks from gm its worth it to not put back on a bolt that could very possibly round off the next time
09-27-2006, 05:06 PM
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Originally Posted by MiaSSmaro98
so u can use the old bolt instead of buying a new one?
09-27-2006, 08:29 PM
#15
I usually put the breaker bar on it, then slide the 4 foot jack handle over the breaker bar and tighten till the rear wheels start spinning in fourth gear with teh parking brake on. The only crank bolt I ever broke was the longer bolt, an
d it broke on teh way out.
d it broke on teh way out.
09-27-2006, 08:43 PM
#16
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Originally Posted by GuitsBoy
I usually put the breaker bar on it, then slide the 4 foot jack handle over the breaker bar and tighten till the rear wheels start spinning in fourth gear with teh parking brake on. The only crank bolt I ever broke was the longer bolt, an
d it broke on teh way out.
d it broke on teh way out.
09-28-2006, 12:41 AM
#18
The bolt is about $5 so you can't justify not buying a new for the tiny amount of money you'll save. It could end up costing you a lot more than $5 in the long run if you do decide to reuse it. If you use a LONG breaker bar you can get a lot more torque. I put a piece of pipe over my breaker bar. It ended up being over 4' long and makes getting the torque I need to either take the crank bolt out or install a new one a whole lot easier.
