namyessam
Gold Member
If you end up drilling it out, use a high quality high speed steel drill. You could start with a smaller drill maybe a 3/16 or so to make drilling with the large one easier. I believe the bolt is a 7/16 diameter so use at least that size or 1/64 to 1/32 larger. Most Allen head bolts are grade 8 and are tough drilling. Spin your drill slowly, 250 rpm or so and light pressure to start with until you get past the hex and into the base of the bolt. When an Allen head bolt socket has been stripped out it seams to work harden them and make it even tougher. You should only have to go a short distance and the head will pop off and probably get stuck on the drill and you should be able to pull it out of the hole. I would think you should be able to lift the valve off the bolt shank. Remember to clean the chips off good to keep them out of the hydraulic ports when the valve is lifted off. I thought you said you felt the thread were loose and that is the norm for Allen head bolts, Its been my experience that the head sticks to the bolted item and the threads are loose and as soon as you drill the head off the rest of the bolt unscrews with your fingers. Good Luck.
Just to let you know, I am a journeyman toolmaker with 30+ years experience. I use Allen head bolts on a daily basis. Allen head bolts are the primary fastener used in tools for industry. They are normally in a counterbore so they are below flush with the surface. I had to drill one out last week and used the same process I described above because "Jack Armstrong" overtightened the bolt. Use your best judgement. I was reluctant to post this informatin due to the conflict earlier in this thread but reconsidered because this in my line of work. Its what I do for a living. Good Luck again.
I should correct myself and call the bolts by the proper generic name of socket head cap screws. A left hand drill is an old trick that it bites hard enough it may back the bolt out with out completely drilling it out. What ever method you use, don't break a drill or an easyout or you'll really have problems. I know this is a wild idea but can the whole valve be turned with the stuck bolt intact?? My tractor is 50 miles away and I can't look at it to see if there is suciffient clearence to do so. If that is possible it may solve your problem. This would destroy your o-ring which should be replaced any way. I don't see anything in the parts breakdown that sticks down from the valve or sticks up from the top cover. Maybe someone like MasseyWV can confirm this.
Just to let you know, I am a journeyman toolmaker with 30+ years experience. I use Allen head bolts on a daily basis. Allen head bolts are the primary fastener used in tools for industry. They are normally in a counterbore so they are below flush with the surface. I had to drill one out last week and used the same process I described above because "Jack Armstrong" overtightened the bolt. Use your best judgement. I was reluctant to post this informatin due to the conflict earlier in this thread but reconsidered because this in my line of work. Its what I do for a living. Good Luck again.
I should correct myself and call the bolts by the proper generic name of socket head cap screws. A left hand drill is an old trick that it bites hard enough it may back the bolt out with out completely drilling it out. What ever method you use, don't break a drill or an easyout or you'll really have problems. I know this is a wild idea but can the whole valve be turned with the stuck bolt intact?? My tractor is 50 miles away and I can't look at it to see if there is suciffient clearence to do so. If that is possible it may solve your problem. This would destroy your o-ring which should be replaced any way. I don't see anything in the parts breakdown that sticks down from the valve or sticks up from the top cover. Maybe someone like MasseyWV can confirm this.
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