# Kubota M6800 Pressure Relief Valve



## thedugout (Jun 16, 2015)

Hi all - newbie / inexperienced operator here, so go easy on me. 

I recently put a new bucket on my Kubota M6800 - bigger than the original, at least 50% more capacity. Moving dirt and fill, I blew three hydraulic hoses on my FEL in a single day. I recently bought the tractor used, so at first I thought it had been sold to me with bad hoses. Then it dawned on me that I may be going over pressure picking up too much weight, and the relief valve isn't doing its job by bleeding off the excess pressure. So time to check that as a possible root cause. 

Does anyone know where the pressure relief valve is on the M6800, and how to remove it and adjust if necessary?

Thanks!


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## harry16 (Dec 8, 2011)

Hey Dugout,

Welcome aboard the tractor forum.

Attached are diagrams for your Kubota M6800 hydraulic systems. I found at least two pressure relief/safety valves. Look through the parts description for each diagram.


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## harry16 (Dec 8, 2011)

Attached is a loader hydraulic parts diagram for your M6800 tractor. Go to Messick's at top of page to search for more.


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## thedugout (Jun 16, 2015)

Thanks Harry - those are very hy helpful! I'll spend some time studying those and see if I can sort it out. Also got some advice from a local dealer - says the FEL control has a dedicated relief valve that gets adjusted with an allen wrench.


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## harry16 (Dec 8, 2011)

A dedicated relief valve is likely on the loader control valve body. Your dealer should have been able to tell you where to look!

I blew a bucket tilt hose many years ago, by pushing with the bucket at an angle and the control valve in neutral position. This applies force on the cylinder pistons while the fluid has nowhere to go, resulting in extremely high pressure. My hose was old and the weak point in the system. Your hoses are 10-15 years old.


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## thedugout (Jun 16, 2015)

The first two hoses I blew were flexible ones. Then I blew a steel line - sounded like a gunshot, and looking at the line it was obvious a lot of pressure had pushed out the steel. That's when I knew it must be a pressure issue, not just bad hoses. I'll be investigating further when I get back to my tractor Monday.


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## sixbales (May 18, 2011)

You may have an obstruction in your return line which is causing high pressure in the system. I think I would check the loader control valve for blockage first.


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