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question 4341 Super losing oil - leaking into hydraulics?


Level 1
May 15, 2011
Vermont, USA
First name

Zetor 4341 Super, 2x 5211
Hello all,
I've recently become the caretaker of a 4341 Super with two mysterious problems: it loses engine oil at a rapid pace (~1gal every two weeks/6-8 operating hours), and the hydraulics are slow/shuddery, especially when cold. These problems both appeared pretty suddenly, first the slow hydraulics, then the disappearing engine oil about a week or two later. The tractor does not have any visible engine oil leaks large enough to be the culprit (no puddles on the ground), nor is it burning a noticeable amount of oil (no blue smoke, rough running, or oily smell). The hydraulic fluid is full, but appears foamy/aerated after use, and maybe a little cloudy, as though it were contaminated. I've changed the hydraulic fluid and filter twice recently in an effort to alleviate the hydraulic problem, to no avail. The hydraulic pump pickup tube seems to be in good condition, and I have also tried bleeding/priming the hydraulic pump. So, I think that the engine oil is leaking into the hydraulic fluid. It is my understanding that the hydraulic pump on these tractors is driven off the engine timing gear, and this is the only place I can think of where the engine oil and the hydraulic fluid would interface. While I'd have thought the leak would go the other way, since the hydraulic system is usually at a much higher pressure than the engine oil, I am thinking there might be a seal in the hydraulic pump drivetrain that, if broken, could allow engine oil into the upstream, low pressure side of the hydraulic pump.

Am I thinking along the right track? Is there some other way engine oil could escape into the hydraulic fluid? Has anyone else experienced a similar problem? Is there a cure-all part I should replace before I tear apart the hydraulic pump?

Thanks in advance!

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