# John Deere model 790 hydraulic shims question



## Triton4 (7 mo ago)

*Did the 790 come new with any shims for the hydraulic relief valve? The reason I ask is that I bought this tractor used and don’t know if someone has already added shims, so when I take the valve out should there be any shims from the factory? Thanks *


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## sixbales (May 18, 2011)

Hello Triton4, welcome to the forum. 

I cannot answer your question, but it would seem logical that the hydraulic relief valve would be preset at the factory, therefore I would expect to find shims. 

What is your objective here? If you are contemplating increasing the relief valve pressure, I have read on the internet that some guys adjust the valve to yield 2500 psi, which is the typical maximum (design) pressure for a tractor. 

Have you measured your tractor's maximum hydraulic pressure? If you do not have a shop/repair/service manual for your tractor, I recommend that you get one before you start.


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