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What's wrong with my hydrostatic transmission?


Bruker

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I have a `90 model 16GTH that I bought new and all I do is mow with it. I've maintained it according to the manual and I've never had a problem with it until today. While mowing the grass I noticed that I had to push the hydro lever further ahead to maintain speed. Things got worse. When moving from reverse to forward the transmission has started to whine and it can barely make it up a slight incline. Reverse hasen't seem to be affected. Any ideas? Thanks!
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Try checking your hydro fluid. I believe on them,the fluid reservoir is located under the seat deck near the battery. It could be low on fluid. Also, if your tractor has alot of hours on it (in excess of 500 hours) the tranny should be serviced. They have a filter on them, and that may be starting to restrict fluid going to the pump.
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It has about 540 hours on it and I changed the filter and fluid at 400 hours. The fluid level is fine but I noticed it looked a little foamy like some air bubbles were entrained in it.
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OK, is the outside of the transmission (cooling fins on pump, etc.) clear of debris such as grass clippings, dirt, etc ? I only ask this because if the cooling fins are "caked" up with debris, it may be overheating. I never heard of any problems with air getting into the system on those transmissions. They are a reliable tranny.
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you may want to check to make sure the brake isn't tight and or rusty. I have no idea what hydro is in that unit but foam most often means air. If someone like UCD can get you pointed towards a manuel for that hydro check and see how the low pressure is routed and if maybe there is a place where it can draw air. ( Like the filter etc ) I do know the 7000 and 7100's would foam and squeal and many times it was nothing but the short hose from the transaxle to the pump. Even a pin hole that hardly leaks a drop when the machine is sitting will allow plenty of air while under reduced pressure.. Good luck
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Alright. I'm going to drain the oil and replace the filter to see if that clears up the problem. When I last did this I used 30w motor oil as the operators manual specified and the Simplicity filter #1702282 ($26.00!). Does anyone recommend any other type of oil and is their a less expensive filter to use?
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thedaddycat
Try a search for "hydro filter" and other like terms. There have been several in-depth discussions about these filters, and I have decided that the OEM filter will be my only choice even though pricey.....
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  • 3 weeks later...
Kowing nothing about hydrostatics drives but an alot about automobile automatic transmissions this is not a fluid or filter problem because the problem would be in forward or reverse.This is a hydraulic problem.That means a dumping of line pressure somewhere.
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