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Loosening headbolts


Chris727

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Hi. I have been having trouble with the headbolts on my 700, it has the 8hp Briggs Cast Iron replacement engine. When I first bought the tractor I put a new head gasket on. It blew it after a month or less. I noticed the bolts tended to loosen up some. I recently replaced the gasket again, this time I used copper coat on it. All of the bolts were torqued correctly and rechecked before running. After running it I noticed it had blown the gasket again. After only 15 to 20 minutes or running the bolts had loosened to only being hand tight. I had used anti-sieze on some of them. Could the washers need replacement? Do I need to retorque the bolts after warming it up? Has anyone else had this problem? Thanks in advance. Chris
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The problem is the use of the anti-sieze. These bolts exspand and contract a large amount. This stretching allows the bolts to walk themselves out. I'd make sure the head and the top of the block are still both flat. Completely clean the block threads and replace the head bolts with known good bolts and retry.
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Buy new head bolts, the old one stretch and wont hold torque. Install them with a light film of light oil. Torque to specs in the correct sequence. L head cast iron single cyl. is 190 in. lbs. or 15.83 ft lbs in 3 steps 65 in. lbs., 130 in. lbs. and 190 in. lbs. after an hour or two of run time check torque to 190 in. lbs.
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Thanks for the input. I will buy new bolts and will not use the anti-seize. I will also clean out the threads on the block. Chris
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quote:
Originally posted by Ketchamized
Dave, Would it be a good idea to use loctite on the head bolts if they keep falling off? My other tractor has the same problem.
Eric, useing added stuff like loctite and such would be overkill. By useing the above "approved" suggestions there shouldn't be any problems. Also with the softness of the cast iron block, something like loctite would probably remove any threads and severly damage the block.
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Maynard and Dave, Thanks for the warning. It's a good thing I always ask before doing something that may be stupid & damaging to my tractor. :) You guys are saving me a fortune and I'm learning a lot from you. Thanks again.
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