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Crankshaft Bolt
- Thread starter michbc3
- Start date
michbc3
Well-Known Member
The belt tensioner on my car looked like it was working overtime trying to hold tension on the serpentine belt. My brother discovered that the lower pulley was visibly wobbling quite a bit. Suspect parts included the pulley, 3-1/2" hub/spacer and the vibration dampener. So I spent a few hours stripping off everything until I got to the face of the dampener - which I made sure was clean - used light application of a wire brush on a drill. Using a flywheel turner, the face of the dampener where the spacer mates with it has a 0.025" variance. When the spacer is mounted, the surface that meets the pulley has an 0.035" variance. But when you indicate the spacer from the side (radial measurement), you get a whopping 0.075" variance.
I ran the engine briefly like this and the wobble looked terrible. So I didn't bother to go to the next step and mount the pulley. The tensioner is trying to make up for almost a 10th of an inch of belt tightening and loosening with each revolution.
So, it's off with the dampener...
I ran the engine briefly like this and the wobble looked terrible. So I didn't bother to go to the next step and mount the pulley. The tensioner is trying to make up for almost a 10th of an inch of belt tightening and loosening with each revolution.
So, it's off with the dampener...
michbc3
Well-Known Member
Thanks for the advice/encouragement. I bought a 1-1/8 impact socket (which was a loose fit on the bolt) for 3/4" drive, used a 1/2" to 3/4" drive impact adapter in my 1/2" impact gun and got the bolt out. If this is supposed to be SAE,, it's strange that this bolt is so far off from my toolset. I bought a 3/4" drive torque wrench to put the bolt back in when the time comes.
Anyway, took the balancer off and discovered more bad news. The crankshaft snout is all rough/beat up on one side for about 1/2" from the end - so will eventually have to be taken out, re-welded and re-ground. Since I bought this car used, I have no idea what caused this. The previous owner was a maniac who beat the car up blindly. Could have been detonation. Could have been an imbalanced lower end assembly. Lots of work to do now... but at least now I can get the balancer on and off whenever I want.
Best, Bob
Anyway, took the balancer off and discovered more bad news. The crankshaft snout is all rough/beat up on one side for about 1/2" from the end - so will eventually have to be taken out, re-welded and re-ground. Since I bought this car used, I have no idea what caused this. The previous owner was a maniac who beat the car up blindly. Could have been detonation. Could have been an imbalanced lower end assembly. Lots of work to do now... but at least now I can get the balancer on and off whenever I want.
Best, Bob
michbc3
Well-Known Member
Subsequent investigation revealed that an aftermarket camshaft had been installed by the previous owner. When reassembled, the crankshaft bolt was not torqued properly and the balancer walked off of the front of the engine while it was running, damaging the crank nose and bending it a little. So I'm in the process of pulling the original engine out while it is still in running condition to preserve the numbers matching block. I am now building a new engine from scratch.
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