I need help!!!!!I purchased a JD-401C John Deere approx... 1 1/2 years ago!! It is an industrial tractor with a loader. It is comparable to the JD-4030. This is the problem: It has a front mounted hydraulic pump driven from the fan belt pulley bolted to the crank shaft of the engine. The drive shaft of the hydraulic pump is connected to the fan belt pulley with an aluminum cast coupler with rubber bushings that slip over the shafts of two bolts extending from the fan belt pulley and likewise the drive shaft to the hydraulic pump has two bolts extending from it also. The aluminum cast coupler comes in two halves and are bolted together over the rubber bushings for the connection and absorbtion. The problem I have is this: When you look at the cast aluminum coupler clearance between the top and bottom of the fan belt pulley and coupler. There is 1/32" clearance at the top and 4/32" clearance at the bottom. If you bump the starter and rotate 180 degrees the same difference exists at the top and bottom!! With this being out of alignment by 3/32" two things may happen!! The first time I had a problem, one of the two bolts backed partially out of the fan belt pulley and wore a groove in the fan belt pulley and eventually the cast alumimun coupler hit the frame of the tractor! I had to pull and replace the fan belt pulley, the cast aluminum coupler, and the drive shaft for the hydraulic pump! Since making the repair I have no more than 50 to 75 hours of use on it!! I have been keeping an eye on this since replacing it to make sure the bolts did not back out of the fan belt pulley. (I put medium locktite on both bolts.) I noticed that it looked like one of the two bolts had backed out approx.. 1/16" and had planned on removing the cast coupler and removing the bolt and put heavy duty locktite on it this time. I decided to get a little bush hogging done before doing this. (4 hours of bush hogging) When I got ready to remove the cast aluminum couplers and tighten the bolt I took a second look at it and realized that the bolt hadn't backed out 1/16" it was sheared off!!! I have two questions: What should I do to correct the alignment problem to make sure there is no difference in clearance between the top and bottom of the cast aluminum coupler and the fan belt pulley? Apparently the rubber bushings don't compensate for 3/32" difference!! Has anyone got any suggestions on removing the the bolt that has been sheared off in the fan belt pulley without removing the pulley? The bolt is sheared flush with the pulley! I hate to remove the pulley even though I don't think there is any choice!! If I have a problem backing the bolt out with an easyout, what kind of suggestions have you got for removing the bolt? I think it is a 1/2" bolt.
What is the maximum size hole I should drill to remove the bolt easily with an easyout and yet not damage the bolt threads in the pulley? The price of the fan belt pulley is approx... $125
and I don't want to replace it again!! I had a terrible time pulling the pulley last time due to only having approx.. 7" of room for a puller without removing the hydraulic pump. I had to to back the pump out about 1/4" to have room enough to get the puller in!! I realize this is rather lengthy but I hope I explained what my problem is and would appreciate any help anyone can give!! I must get the tractor back in service immediately!! Thanks for any help in advance!! Paul
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