Ford 4000 hydraulic leak

[Red Rex]

1968 model diesel 3 cyl with independent pto.
I have a leak of where the tube exits the pump housing to be flow control valve. I have replaced the o ring 2 times with no stoppage of the leak.

What might be causing this issue? Would a bad pressure relief valve cause this?

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[Chevy 88]

How bad is the leak? Can topping off the fluid from time to time work well enough? Or is the leak so bad that it must be fixed?
I once drove a rig that needed a quart of oil every few miles.
I once drove a rig that needed a quart every 8 hours of operation.
I once drove a rig that needed a quart of trans fluid every time I drove it.
Fluid loss is manageable -until the repair is less of a hassle than topping off the fluid.

I just fixed a rear main last week because I got tired of dumping $300 a month worth oil into the damn engine.


So if you just have a tiny leak that is easily manageable, and the only purpose of the repair is to save the environment - then you should be working on my rigs - not yours.

 

[Red Rex]

How bad is the leak? Can topping off the fluid from time to time work well enough? Or is the leak so bad that it must be fixed?
I once drove a rig that needed a quart of oil every few miles.
I once drove a rig that needed a quart every 8 hours of operation.
I once drove a rig that needed a quart of trans fluid every time I drove it.
Fluid loss is manageable -until the repair is less of a hassle than topping off the fluid.

I just fixed a rear main last week because I got tired of dumping $300 a month worth oil into the damn engine.


So if you just have a tiny leak that is easily manageable, and the only purpose of the repair is to save the environment - then you should be working on my rigs - not yours.

Steady drip a little faster than a leaky faucet. Not manageable when you depend on hydraulics to operate

 

[1STLS1]

Carefully look over the tube and where it is mounting at, anything obvious? Nicks? Tube cracked? Mounting area where tube fits cracked? Elongated?

Are you sourcing the correct o ring? Or finding one that was similar to the old one? Just because it came from the parts house doesn't make it correct, order it from the dealer with model and serial.

Now if that isn't it, try using 2 o rings or try one that is thicker, and if that doesn't work, I would replace the part with the tube.

On difficult leaks that you can not locate, we use UV dye.

I am a close to 30 year fork lift mechanic so I know enough to talk a good game.

 

[Red Rex]

Carefully look over the tube and where it is mounting at, anything obvious? Nicks? Tube cracked? Mounting area where tube fits cracked? Elongated?

Are you sourcing the correct o ring? Or finding one that was similar to the old one? Just because it came from the parts house doesn't make it correct, order it from the dealer with model and serial.

Now if that isn't it, try using 2 o rings or try one that is thicker, and if that doesn't work, I would replace the part with the tube.

On difficult leaks that you can not locate, we use UV dye.

I am a close to 30 year fork lift mechanic so I know enough to talk a good game.

Tube has not been damaged. There is a groove cut in the tube for the o ring so adding a second would not work. Possibly a thicker one would though. I did use new old stock (expensive) o ring and am confident that the 2 I have tried are correct.

I do have a new old stock tube and o rings. I am searching for any reasons as to what might be causing the leak as the leak could be a result of another issue that replacement would not cure.

 

[bucket]

On my much older Ford, there's a pressure relief valve in the bottom of the transmission. It stuck one time and caused a couple different hydraulic leaks due to the excessive pressure. I took it out and cleaned it out, cross my fingers, it's still working fine.

 

[Red Rex]

On my much older Ford, there's a pressure relief valve in the bottom of the transmission. It stuck one time and caused a couple different hydraulic leaks due to the excessive pressure. I took it out and cleaned it out, cross my fingers, it's still working fine.

I have done that but that doesn’t mean it’s not sticking.

Today it started leaking from the top side where it goes into the flow control valve and stopped coming from the lower side. Looks like the lift cover is going to come off, flow control valve coming out and I am going to replace the tube

 

[Red Rex]

Lift cover came off, flow control valve removed, and both the upper and lower tubes replaced. All reassembled. Leak repaired.