New to TractorByNet...help pls

[fixer4u]

Hello All. I am new to this forum and I'm needing some help. I'm at a loss. I'm a Millwright and know hydraulics, but this one is stumping me. I am trying to figure my 3 pt hitch on my Ford 335. I have resolved a leak and now need to find out why it is still not working properly. Oil level is good, got it going up and down with neighbor standing on it. Put a heavier load on it and wouldn't lift. Leaving the Draft control in the lower position, so that I have Position Control of the arms, as per owners manual. Checked oil and it was real foamy. Understandable as had to bleed air out after dealing with low oil and a leak. Waited until the air dissipated out of the oil, and now it will eventually move up, no load and is spongy, which to me, still means air in the system. Oil is not foamy at this point. It's a gear pump on the rear left side of the engine with inlet filter mounted at the pump. Filter is tight and fairly new, don't believe that it is sucking air past gasket. I'm open to all suggestions and please ask me any question to this issue and I will answer it to the best of my ability and knowledge, (in case I missed something important), as I have owned the tractor for 6 years (never owned one before), but have only recently started to use the 3 pt due to a great neighbor that has a smaller HP Kubota but has some CAT1 attachments that have been offered for mutual benefit due to my 335's HP. It would be nice to get it operational, so that I can offer some payback for my neighbors generosity. Thank you in advance to all whom offer suggestions and what direction to take with this.

 

[Torvy]

Welcome to TBN! I'm sure someone Herr who loves those older machines will have a good answer for you. Most of the folks here are good people...even the ones who disagree with me!

 

[fixer4u]

LOL...there is always someone who disagrees. As long as there is a discussion that has positive results and people don't hold a grudge. Thanks for the welcome.

 

[oldnslo]

Did you replace the filter with OEM or aftermarket? Some tractors aftermarket filters cause problems.

Does the pump get noisy or growl when trying to lift a load on the 3 point? If yes this would point towards pump be starved for oil.

Is there any inspection cover you can remove while tractor is running to see if oil is spraying out inside the tranny housing when trying to raise the load vs not trying to raise. Oil spraying out will also cause foaming.

 

[zzvyb6]

Dirt or some other contamination is keeping the pressure relief valve stuck partially open. Maybe something came loose while changing fluids & filter. I've seen this happen with the wrong viscosity hydraulic fluid, too.

 

[oldnslo]

Relief should only open if trying to lift to heavy of a load and allow dirt to enter and hold it open. Possible but something happened causing the relief to open initially.

 

[sd455dan]

By Leak repaired , do you mean like the rockshaft piston seals replaced?
If the 3 point is lifted and tractor turned off does it stay up?
Just wondering if it could be bad Rockshaft piston seals? They do fail at some point . My For 3000 needed to have them replaced as did my other tractor. Just can't remember whether the 3000 would lift much weight when they failed I do remember both 3 points leaking down when the seals were bad. But was thinking both would still lift well over 1K just wouldn't hold it, the valving would have to correct the height. Sounds like the PRV is leaking like the previous poster suggested.

 

[Harry in Ky]

If you've never used the three point, then what did you do with the tractor? What other hydraulic functions does that pump supply that have been used thus far?

As for air in the system. I've seen all sorts of filter brands used with that style pump and the brand has never been an issue. The pressure relief valve is on the lift cylinder assembly and won't have much bearing on air on the suction side. The entire pump output eventually winds up in that area anyway, so that won't necessarily create foaming of the oil.

Air ingestion (if that's actually your problem) will come from the suction side, not the return. There isn't much to the suction side other than a tube and some O rings. If you feel pretty sure that base is covered, I would lean toward the pump itself. Is it squeaky clean on the outside or is it kind of dirty and oily? The answer to that really doesn't prove anything, but if it's dirty, then the body seals are probably the reason. If those are hard and brittle, there's a good chance the shaft seal is also. That could be a source of an air leak since the pump is mounted higher than oil level.

Have you considered trying to take some pressure readings anywhere in the system while trouble shooting this?

 

[TractorTech]

Harry in Ky is right about the suction or shaft seals being about the only points of air that can be introduced.
The suction tube coming across the bell housing is held in the pump by a tube clamp at the center of the bell housing. If this tube was removed, it is critical to get it seated in the pump past the oring on the pump. And then, make sure the pipe clamp holds it in that position.
We are all curious as to what was repaired to be able to assist you.

 

[zzvyb6]

Relief should only open if trying to lift to heavy of a load and allow dirt to enter and hold it open. Possible but something happened causing the relief to open initially.

Sure. Like raising the 3pt full up. Maybe a piece of seal tore loose and has became trapped.