Farmall 450 hydraulics

Fast hitch cylinder - raises and lowers with nothing attached. When I put a 7-ft back blade on, it may not lift at all or it might partially lift. Generally, it will raise a 4 or 5 inches and then stop. I found this while grading a driveway last week. After parking it, I also noticed oil slowly dripping from the cylinder (hoses are new).

Behlen power steering It steers fine in either direction and there are no noises that I would associate with the unit. I know the return hose needs to be replaced and the output shaft seals are leaking enough to leave oil on the valve cover.

Earlier this year I drained the hydraulic system and replaced it the fluids with Hytran. The filter screen was checked and looked nearly new. I cycled valves and steering multiple times to circulate the new fluid into the system. I found that even then it appeared to have air and/or water (discolored and foamy). When it is not running the oil is correct color. I ve opened the drain plug slightly to remove any water that might be in the bottom of reservoir. No obvious sign in the -1 cup of oil I took out.

I have not used the tractor other than to move it in and out of the barn a couple of occasions until grading the driveway. Yesterday I found that the reservoir needed nearly a gallon of Hytran to fill it. The engine oil level is good (not making oil) so assume the pump (M&W 201PX) seal is good.

My questions:
1) Would the leaks on either of these units draw enough air to discolor the oil under operation?
2) I have ordered a seal kit for the fast hitch cylinder, but wondered if the power steering output seal could be replaced without tearing the unit down?
3) Can the fast hitch cylinder leak enough (bypass internally) so that it would not be able to lift under load?

Thanks in advance
Randy

EDIT:
Input shaft seal in the Behlen unit not output

Foaming can be caused by sucking in air or a bad pump. The place a 450 will suck air is where the
pipes attach to the valve mounting casting either at the o-rings on flange or gasket between upper
and lower casting or maybe even o-rings at pump flange.

Seal on power steering can be replaced without total tear down. There first off is a dirt seal you
remove. Then a snap ring that holds in a spacer that contains o-rings on inside and outside.
Problem is, the shaft often wears making it difficult to seal.

When using the hitch, turn steering to stops and hold it there to see if hitch acts different. If
it lifts less or slower, you have a bad pump.

Thanks Pete, I ll have to tear into it to check the o-rings and gaskets. Was hoping to delay that for now.

I plan to address the power steering seal in the near future, with my luck it likely will require a full rebuild.

As to the fast hitch operation with the steering all the way to the stops - no change. I did try it in both directions.

have you check your engine oil? If higher than it should be, the hydraulic fluid may be slipping past the seal on the shaft. Which then means that you can become low on the hydraulic fluid in the hydraulic system. Simple fix.

Just to add to number 3, I see you have already ordered seals for the Fast Hitch cylinder. That is
good if it leaks it needs repair. What I want to add is if after the hitch raises the blade and then it
stops and you center the lever and the blade holds that position the problem is not because the
cylinder is bypassing. If it was bypassing it would basically drop back to the ground.

Thanks for the replies

SDE - I did check the engine oil level. It is still at the full level mark and is not gaining anything from a seal leak on the hydraulic pump.

Used red - I cannot get the hitch to lift with anything attached to it. It will raise with "no load" on it. My current guess is that it is bypassing within the cylinder when there is a load.

I m assuming that the test pete 23 suggested was to check the operation of the priority valve. The power steering functions well and there was no change to lifting capability with the steering to the left stop or to the right stop.

Hoses out of the pump are new and the hoses to the fast hitch cylinder are new. I did not rebuild the pump.