450B blade hydraulic

[Coreo19]

450b dozer. Has manual 6 wayblade. Hydraulic up and down. At idle the blade will go up and down on its own fine. If you bump throttle up to anything over idle the blade will come half way up and stop there. You can mess with the lever and it will come the rest of the way up.

Tee’d in a gauge going to one lift cylinder and at idle it’s only putting out 500psi. With cylinders dead headed it’s only putting out 500psi. I’m under the assumption it should be closer to 2000psi

I can hold lever back until cylinders stop and it’s only putting out 500psi so I assumed the relief valve was going open so I took it out and it had zero shims in it. Put in one shim and got pressure up to 700. Am I on the correct path here as far as trouble shooting? Or am I missing something simple?

Dozer is new to me. Bought it and put steering clutches in it so I know very little about how the dozer acted before the replacement of steering clutches

The filter in the hydraulic tank has been replaced and the suction screen has been pulled and cleaned didn’t help at all

[Jim B]

Welcome to the forum. Sounds like you have a 6410 dozer blade (outside mount, hydraulic lift with manual tilt and angle).

If you have a bad cylinder, Teeing the gauge in with either or both of the cylinders still receiving oil may not give you a true relief valve pressure reading. Oil could be bypassing a cylinder packing without building full pressure. True dead heading would have the gauge blocking any oil going to the cylinders.

Do you have Technical Manual TM1033 for the 450B? If you don't have a copy here is a link to a on line copy you can download. https://archive.org/details/John_Deere_ ... ual_TM1033 The hydraulic section has the recommended diagnostic procedures and the specifications you can follow. If you want a hard copy to have, contact Lavoy, he may have one available in his store.

[Coreo19]

Jim thanks for the warm welcome to the forums. On page 208 of the manual you sent me. It says to put a gauge on somewhere and it shows a picture but I can’t make out where it is telling me to put it to check system relief.

I work off Saturday morning and will attempt to verify both lift cylinders are good or bad. Thanks for the help so far!

[Jim B]

The "window" they are pointing at the fitting in, is below your right arm rest. The frame the seat cushion (removed) sets in is shown.