4020 Hydraulic pump overflow return line Ar34768

[AltaTexan]

I have a 1966 4020 synchro range tractor. I have rebuilt the main hydraulic pump twice and then bought a new flow tested hydraulic pump from the jd dealer to fix the problem. But every time within five minutes of running the tractor the low pressure plastic return line from the front that dumps into the back of the tractor Ar34768 ruptures.
For some unknown reason it constantly ruptures 3/4 of the way down the line. There is no known obstructions. It passes fluid freely before running the tractor. I have even blown through the line prior to hooking it up from the upstream side and had zero restriction. Has anyone else seen this issue? Ive now blown 5-6 of these lines and nobody at the dealer can tell me what is going on. Any old boys have a clue?

 

[wore out]

(quoted from post at 14:59:27 04/15/22) I have a 1966 4020 synchro range tractor. I have rebuilt the main hydraulic pump twice and then bought a new flow tested hydraulic pump from the jd dealer to fix the problem. But every time within five minutes of running the tractor the low pressure plastic return line from the front that dumps into the back of the tractor Ar34768 ruptures.
For some unknown reason it constantly ruptures 3/4 of the way down the line. There is no known obstructions. It passes fluid freely before running the tractor. I have even blown through the line prior to hooking it up from the upstream side and had zero restriction. Has anyone else seen this issue? Ive now blown 5-6 of these lines and nobody at the dealer can tell me what is going on. Any old boys have a clue?

Install a new line and leave it disconnected at the back and start the tractor and see what happens.

If the pump primary seal and the steering "motor" are in good shape there should be NO flow from the line.

Is there flow from the fitting where it's supposed to be connected, IIRC, the brake valve return line an possibly a leak-off line from the steering all "tee" into that fitting on the transmission case.

 

[Tx Jim]

Welcome to YT
I agree with wore out. Start engine with line disconnected from brake valve & report results back here. I'll guess ball(item 15) isn't seating properly.

 

[Glen D Anderson]

On our synchro range tractors the case drain for the steering motor is connected to the hyd. oil cooler via a separate line...

If the pump primary seal and the steering "motor" are in good shape there should be NO flow from the line.

Is there flow from the fitting where it's supposed to be connected, IIRC, the brake valve return line an possibly a leak-off line from the steering all "tee" into that fitting on the transmission case.