John Deere 300B backhoe

Timbo2150

New User
My 300 B hydraulic system slows right down after it warms up. The first 20 minutes it runs perfect. The oil is up to full mark . I did see discussion on here saying to clean a screen at the bottom transmission but cant find that conversation again. I was wondering were that screen is and will I loose oil by pulling that out
 
Is this it? Yes you will lose the oil. You can put a shop
vac on the full tube an pull a vac on it while you pull it
out. There will be air being pull in around the filter as
you pull it out so there is a possibility of pulling crud
from around the screen back in the housing if you use
this method.
This post?
 
Running fine when the oil is cold and then slowing down after the oil is warm sounds to me like
your hydraulic pump is worn, rather than a screen that is plugged. Have you checked the pressure
on the hydraulics when the oil is warm?
 
Check the suction screen and change the transmission filter. It's an inexpensive place to start. If the transmission pump isn't getting enough supply, it can't properly feed the front mounted hydraulic pump that supplies steering, brakes, and other hydraulics. I have experienced the good hydraulics when started and lose them after running a short time. Found a plugged screen and a dirty transmission filter. Material can drop away/loosen from the screen when setting and pull back tight after running a few minutes. I would dump the fluid into a clean container (expect 10 plus gallons to be safe), so any crud comes out rather than holding it back with a vacuum. If the fluid is clean, it can be put back in. Found a lot of brake material on the screen. A cleaning and a brake job solved the hydraulic problem on that one. If you have to get or add fluid use Hy-Gard or an equal JDM JD20C UTHF.
 
When the hydraulic filters on my JD 410 backhoe get plugged the hydraulics become slow, due to the
problem like you said of the oil not getting through the filter up to the hydraulic pump. However,
when this happens it is always worse when the oil is cold and improves as the oil gets warmer.
 
As DRussell mentioned, it could be that your transmission pump is worn, and then the big pump doesn't get enough oil. Or could be a leak
internally between the two.

I had a 400 backhoe I had to keep the transmission way over full, otherwise it would have the same issue as yours.
 
thanks for the help I have drained the oil and have the screen out and yes it was plugged. I am changing the filters and putting new oil in. I dont have a manual , does anyone know how much oil it takes to refill
 
10 gallons plus or minus. You should use a UTHF like Hy Gard or an equal meeting the JDM J20C spec.

What did the material on the screen look like? Fiber flakes? Did you cut the filter open and see if it had metal fines in it? did the old oil look silvery, like it had anti-seize in it? Those can be signs you need a brake job.

This post was edited by Jim.ME on 05/16/2022 at 03:28 am.
 

I suggest you check hyd oil filter relief valve(items 18-20) to be sure it's not stuck open.
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