# Belarus hydraulics



## Rob30 (Nov 2, 2004)

I had a small leak in my control valve that caused the hydraulics to over heat. After changing the valve bank, I baled 90 lrg round bales. The next time I started the tractor the pump went on it. I know there was a bunch of junk in the control valve bank. Now that I have eveerything back together I want to know if there is a way of flushing the system? I cleaned everything I could when it was apart. I even cleaned the by pass valve in the new control bank. I am not sure if it stuck and thats why the pump cooked.


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## DaleK (Sep 23, 2004)

Don't know Belarus but if there was that much junk in the system on one of my tractors, I'd probably run it for a couple of hours to heat it up and get things moving then drain the oil, change the filter(s) and put new oil in it. Matter of fact that's just what I'm doing on my 7510 tomorrow.


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## Ross (May 9, 2002)

How does a small leak make it over heat? I'm going to guess the pump was dying and throwing junk into the block. As Dale says fill heat and flush is about all you can do. Belarus systems are pretty forgiving If I remember right you can use pretty much any grade of oil. Maybe a lighter weight hytran type would be better. Walmart sells it cheap, Can tire did and might still.


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## agmantoo (May 23, 2003)

Ross,
The hydraulic oil, under high pressure, being forced through the restriction of the small leak generates heat from friction and the pump running. Most tractors lift hydraulics were intended to be used intermittently, I imagine that Rob30 was having to constantly correct for the leakage before the repair, maybe even at times having to hold the level on. This would be abusive to the hydraulic system. I would think he has a screen or a filter clogged at this time. Only by using a set of gauges to determine the pressures present will he be able to trouble shoot the problem with confidence.


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## fordson major (Jul 12, 2003)

how bad was the filter in the reservoir rob? can be quite a job too get all the crap outa those discs! so you guys up da valley are getting sun? brought some cooz home from Eganville on sat, lots of sun there but more rain and micro bursts here!


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## haypoint (Oct 4, 2006)

Belarus hydraulic systems use 30 weight, unlike just about any other tractor.


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## Ross (May 9, 2002)

30 weight is in the owners manual but if you ask a dealer (in Canada anyhow) they should be able to show you the full specs which include the different oils used everywhere from the tropics to arctic. Hytran is never mentioned but it works fine. To keep the tractors all using the same oil (like our Fords) for implements we ran hytran for the 15 years we owned the 820 and in the 420. Never gave us any trouble.


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## Rob30 (Nov 2, 2004)

Small leaks in a hydraulic system produce alot of heat. I use the same port for my loader and my baler. The leak was bad enough my loader would raise all the way up going one consession. I fixed the leak, baled for one day, then the pump went. I may have been using to thick of oil though. I had hydr 68 in it, hoping it would not leak. I just bought hydr 48. Is that still to thick? Should I stick to hytran fluid? I power the haybine with both the belarus and a ford major.


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## Ross (May 9, 2002)

OK I'm gettign caught up, an internal leak past the vavle, yeah that would heat things up. Could have been a chunk of pump damaging the O ring or valve in the first place though. Ever see any grit in the oil? We use hytran in all our hydraulic systems because I don't want cross contamination, when we switch tractors.


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## agmantoo (May 23, 2003)

My experience with hydraulic systems is that pumps themselves rarely fail catastrophically. Instead, they ceased to make adequate pressure. Failure of pressure is again IMO caused by either starvation (cavitation) of oil supply or by a failed relief valve (trash under a seat or broken spring). Sometimes a blown O ring or gasket can also create the problem. Is there any chance that an O ring got substituted (wrong size) or did not get properly placed when you changed the valve?


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## Rob30 (Nov 2, 2004)

When I say the pump failed, what happened is oil started pouring out between the two haves of the pump. A seal went. The belarus dealer said that is what happens whent the pump goes. He also says the pump is now scrap, but I am not sure. There does not appear to be any damage. 
As far as oring being misplaced. I don't think that happened. I did not touch any orings. All conections are connected with brass washers. 

I am suprised the pump went myself. Because I have been told the belarus has one of the strongest hydraulic systems.


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## agmantoo (May 23, 2003)

I am not that familiar with the hydraulic system on the Belarus. I know a little something about hydraulics. IMO, your pump went bad as a consequence of something else. The pump is obviously a positive displacement design, is that correct? The pump was making pressure and the oil was restricted and something had to give so the seal went. There is a pressure relief valve in the system and that relief valve should have permitted the high pressure to relieve. Why it did not relieve is what IMO you should be looking for. I would think it is blocked with debris. 
If the pump housing did not distort and nothing sheared it should work again with a new seal. When the seal blew were you able to hear a squealing sound from the pump area immediately prior? Was the new control that you installed an exact replacement? In the off/neutral position of the control valve the pump should be able to dump back into the reservoir. Is there any chance the plumbing is incorrect or that the valve is not dumping?


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## Rob30 (Nov 2, 2004)

There is a relief valve. I opened it up and cleaned it up. It seems to be moving freely. 
As far as the pump goes, I didn't hear anthing before it went. I only noticed because of all the fluid leaking off the tractor. 
How can I tell if the relief valve is working now? 
Would have too thick of fluid cause the problem. Like I said I was running 68 in the system. I have some hytran that I will put in this time.
Any ideas, I am a little nervous about starting her up, but I need to make at least 150 more bales this week.


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## agmantoo (May 23, 2003)

When the relief valve was assembled there was nothing "moving freely" was there? When you opened the relief valve, did it have a shims, a spring and a steel ball? Could you tell if someone had ever open the relief valve previously? There are different designs of relief valves and I ask the questions trying to determine if the relief valve was preset or adjustable. If it is adjustable how do you know you have it properly set since opening the valve? Was the orifice hole viewable to where you could see it was not clogged? A heavy/thick fluid will not flow as readily and will build more resistance through a given orifice. If the pump failed as you revved the engine the incorrect oil could have been the cause. Why not try a new seal with the correct oil and see the results. Initially let the tractor idle until you see if the hydraulics are working. The volume and thus the pressure of the oil pumped will increase as engine RPMs increase. How the pump behaves as the engines speed is increased will give you an idea of what is happening should it fail again. If you think the pump may have a problem priming place some grease on the parts inside the pump when you install the seal.


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## Rob30 (Nov 2, 2004)

I put the new pump on. Everything works, no leaks. However I did notice a noise coming from the pump. Not a bad noise, I just can hear it running. I did not notice this with the last pump, but I wasn't listening. The belarus has a draft control, and when applied I noticed the engine started working harder. The problem hear is I found my loader and hydraulic ports are more responsive with the lever pulled for some reason. I don't know why, because I can not see the link between the two. 
The relief valve is a spring type. There is no adjustment. I had a local dealer show me how to remove/clean it.
Sure hope this works. It is hard enough fighting the weather to make hay.


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