Hi again. I posted something about this a while back. I haven't had any luck figuring it out and thought I would try again for any insight from others. I just picked up a lx865. It starts and runs smooth. As you throttle it up it runs smooth to about 3/4 throttle. Then it immediately breaks into a vibration and kind of a humming sound. If you throttle down it remains until you are a little less than 1/4 throttle. From there you can throttle up smoothly to 3/4 then vibration starts again. It feels like something orbital, that runs out of balance at 3/4 throttle and then will not re center until it slows to 1/4 throttle. The motor was removed and rebuilt by previous owner. I am thinking something in wing box or a hydraulic pump. I pulled the belt and ran it. Not in fan. Crank pulley not walking in and out. Motor does not seem to be source of vibration. Any insight on bad pumps or wing box issues would be greatly appreciated.
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antfarmer2
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I would look at the tensioner spring and the piviot point for wear
Ok. Thanks. Can you be more specific? What tensioner spring and pivot point?I would look at the tensioner spring and the piviot point for wear
antfarmer2
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On the belt from the motor to the pumpOk. Thanks. Can you be more specific? What tensioner spring and pivot point?
I have no idea what you're talking about. The pumps are gear driven. The only belt on the motor is fan belt. I took it off and ran it. Still vibrates.On the belt from the motor to the pump
antfarmer2
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Ok then it is not belt driven then it has u-joints like mine stop running it and pull the engine u-joints are about a hundred bucks from loaderpartsource if it lets go it can tear up a bunch of high dollar stuffI have no idea what you're talking about. The pumps are gear driven. The only belt on the motor is fan belt. I took it off and ran it. Still vibrates.
I believe the pumps are driven by a flex plate coupler which could have cracked but don't take my word for it. No u joints in there at least.Ok then it is not belt driven then it has u-joints like mine stop running it and pull the engine u-joints are about a hundred bucks from loaderpartsource if it lets go it can tear up a bunch of high dollar stuff
As mike10 told you the 3 cyl engines in most makes do vibrate, ford tractors used to have a extra shaft internally to help balance them but didn't seem to help a whole lot.
Thanks for the flex plate idea. I did some research. The pumps are gear driven. One gear on crank. One gear on each of two pumps. I pulled the cover where a third pump for high flow would go, if I had it and gears seem good--tight, no abnormal tooth wear or sign of running out. I'm checking into something with pulley/balancer on crank and an excessively leaking hydraulic line under left pump. This vibration I am describing is not related to being 3 cylinder. It is significant. It kicks in and out like flipping a light switch. Thanks for all the input. Any other ideas/experience greatly appreciated.I believe the pumps are driven by a flex plate coupler which could have cracked but don't take my word for it. No u joints in there at least.
As mike10 told you the 3 cyl engines in most makes do vibrate, ford tractors used to have a extra shaft internally to help balance them but didn't seem to help a whole lot.
Have you checked all motor and pump mounts to make sure they are all ok? Sounds like something may be loose or the rubber pad is bad.Thanks for the flex plate idea. I did some research. The pumps are gear driven. One gear on crank. One gear on each of two pumps. I pulled the cover where a third pump for high flow would go, if I had it and gears seem good--tight, no abnormal tooth wear or sign of running out. I'm checking into something with pulley/balancer on crank and an excessively leaking hydraulic line under left pump. This vibration I am describing is not related to being 3 cylinder. It is significant. It kicks in and out like flipping a light switch. Thanks for all the input. Any other ideas/experience greatly appreciated.