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bimm

hydro 9020

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bimm
WHILE CUTTING MY LAWN LAST NIGHT WITH MY POWERMAX, THE HOT LIGHT STARTED TO GLOW DIM, WITHIN A FEW MINUTES THE LIGHT WAS MUCH BRIGHTER. I STOPPED THE TRACTOR AND FELT THE COOLER ON THE MOTOR AND IT WAS COOL, I FELT THE TRANSMISSION AND IT WAS VERY HOT. I WAS MOWING IN 2ND GEAR WITH HYDRO FULL SPEED AND ENGINE AT 3/4 THROTTLE. THE COOLING FINS WERE VERY LIGHTLY COVERED WITH GRASS CLIPPINGS. I CLEANED OFF COOLER BUT NO CHANGE IN TEMPERATURE. I CHANGED THE FLUID EARLIER SUMMER(REMOVED SENSOR AND DRAIN PLUG AND TOPPED OFF FLUID DID NOT WANT TO RUN PUMP DRY, LIKE MANUAL SAYS TO DO). HAS SOMEONE SEEN THIS BEFORE? COULD THERE BE A RESTRICTION SOMEWHERE? BIMM

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BradW
You need to run the motor full throttle, the hydro will not cool good enough with 3/4 throttle, not to mention you get a better cut with full throttle, just run full throttle and it should be fine, people have brought them in to the dealership where I work for that kinda stuff and this solves there problem, good luck, -BradW

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powermax_paul
I agree with Jeff, If you're running full tilt in 2nd range, and at 3/4 throttle, either you have a very light lawn to mow or your hydro isn't pushing your tractor as quickly as it should be. When I mow, I'm probably running 3/4 throttle as well, but if I'm in 2nd range, I've probably got the Hydro lever at 1/3 or 1/2. Usually I run in first range at a greater hydro position especially in hotter weather. At a lower gear, the hydro pump has to turn faster and pass more flow and thus more flow passes thru the cooler. This is a much better situation. In second range, the pump runs slower but at a higher pressure which creates more heat and more leakage. Leakage=Heat. I'm thinking that you may have internal leakage in your hydro unit that may be overheating the oil, such as thru a relief valve or acceleration valve. Otherwise, you may want to check your sensor. It too, after all these years, could be going bad and giving a false reading. Paul

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JeffG
Brian, Not sure it will be that simple, as Brad suggested. Your engine should run at 3600 rpm under load. Most people have it set to run at 3600 rpm wide open. You can change the rpm by adjusting the governor spring tension and throttle linkage. My first suggestion would be to mow in 1st gear - you must be flying running flat out in 2nd gear. This will definitely cause an overheating condition in the hyrdo pump. Hard to get a quality mow job running at that speed, anyway. In addition, after changing the hydro fluid, you must bleed the pump to make sure there is no air in the system. Finally, all sheet metal parts (including the back plate) must be in place and make sure you have a good seal between the engine and hydro cooler (many times the rubber seal on the hood divider is missing, which allows hot air from the engine to get pulled through the cooler). Always keep the cooling fins clean on the cooler and check your hoses running to the cooler. The hoses run very close to the steering knuckle and sometimes develop a leak or get pinched slightly. Hope that helps. Jeff

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