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Clutch not releasing completely on 738

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I have just finished replacing the engine on my 738 with a new Briggs 8 HP. The old engine was not in running condition when I removed it but I was careful to measure the shaft length and the position of both pulleys befor I removed them. The shaft length on the new engine is the same as the old and I have positioned the pulleys the same as on the old engine.

The problem is that the large pulley on the transmission continues to turn when the clutch pedal is completely depressed, so that when I try to put the tractor in gear, the gears grind. The belt appears loose on the bottom, but there is sufficient contact on the top side to cause the large pulley to rotate at a good rate of speed. I asked the former owner if this had been a problem when the old engine was running and she indicated that gear changes were smooth and noise-free. The tractor sat idle for 6 years after the old engine expired so there was a great deal of mud dauber dirt crusted on the pulley, but I gave it a thorough cleaning, and the results were the same. Any ideas?

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ka9bxg
It's not the pulley alignment as much as those little pieces of wire next to the pulley called the belt guides. If they are not positioned within 1/16-1/8 " next to the traction pulley, clutch disengagement is next to impossible. The purpose of the guides are to force the belt forward off the pulley groove to effect disengagement when the cltch pedal is depressed. This is generally the most common problem when the belt is replaced. Hopefully you have grease marks on the underside showing how these guides were positioned becase there is a long and short guide and from memory I can't tell you which goes where and the Simplicity repair manual isn't worth a hoot in that area.

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tej
Mike, I'm not familar with the 738 but on the B series ACs the brake can keep the clutch idler pulley from fully disengaging. Disconnect the brake when adjusting the clutch and then adjust the brake so that it is engaged only when the clutch pedal is fully depressed. If the brake is keeping the clutch idler pulley from fully disengaging no amount of adusting on belt guides will correct the problem. Tim

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AdamF
Mike, also check the pulley itself. Since the tractor sat for a good while the pulley may be rusty. This would also cause the belt not to release. If so usually all you need to do is clean it up with a wire brush or some emery cloth. I've seen this happen a number of times and it usually works. Hope this helps. AdamF

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Guest
Thanks to Bob T. for what seems to be the correct cure. Although I don't know how they got out of place, the belt guides were no where near where he said they should be. Adjustments made, and it seems the problem is solved. Thanks again.

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