460 hydraulics sucking air.

I replaced the center section on a 460 I bought because the TA and hydraulic pump were bad. A new o-ring between the center section and the rear end was installed along with all other gaskets to do the job. There is a new high capacity filter on one end of the suction tube and all gaskets on that are good to go. The 17GPM pump I installed had what appeared to be a good o-ring in it so I installed it on the suction tube and buttoned it up. I'm running my hy-tran level about an inch above what it should be. Is there any other areas the pump could be sucking air? I put a fully hydraulic loader on it. The large cylinders have been rebuilt and I re-plumbed it and put a few new hoses on so there is a bunch of air to work out of the system. It seems like it's taking way too long to work out. The power steering comes and goes. When it goes I lift the front end up with the loader and cycle it left to right 5-6 times and then it will work for a while. The fast hitch is still full of air even after cycling it up and down dozens of times. There is no weight on it though. The loader is slow and still full of air. Any thoughts? Does it really take hours to work it all out? I was thinking that 6 or so limit to limit cycles of the power steering and both functions of the loader would get almost all the air out making the hydraulics fully functional and the remaining little bit would be gone over time. As soon as I think mine are getting better they get worse and hardly work. There are a couple of areas on the loader that are leaking a bit of hy-tran and it's all milky and full of air.

When you say o-ring on the suction tube of pump, just what are you referring to. The pump has an o-ring inside the inlet the suction tube goes into, but the tube itself has a lip seal that seals in the counter bore of transmission housing that leads to the hydraulic filter. That seal has to fit tight in the counter bore and must be basically bottomed out when pump is installed. It also moves on the tube to adjust to the length you need for different pumps. That is the first place I would suspect. Other two places, gasket and o-ring between the two piggy back pumps and then the gasket on the filter itself. If you are confident the main suction tube to the rear end is good that is about the only places to suck air.

I was referring to the o-ring in the slot of the pump itself that goes over the suction tube. I had the tractor split and did all of this two winters ago so I can't recall the other one you're referring to. It sat for a while and I've only had the loader on for a month now. I've only used the loader for a couple of hrs. just recently. What is the height of the hy-tran in the casting cavity the pump is located in? Why is it lower than the o-rings we're talking about? How can it suck air there anyways unless it's vented to atmosphere? Not questioning you, just trying to wrap my head around this.

Are you sure it is not the filter and bypass screen plugged already? You have a center section that is "new" to you and a 17 GPM pump. You may have sucked up debris off of the bottom of the transmission plugging your filters.

Wouldn't hurt to check and confirm that it is not.

Air should work out after a few cycles. Do not hit the ends of your strokes while trying to get the air out. Fuel, (aerated oil) pressure, (1200 psi relief) equals possible burning of the piston seals. Diesel engines can ignite fuel at 400 psi or so.....your hydraulics at 1200 is a bit higher than 400. Have seen this on large excavators, burned seals.

I already replaced the filter with an industrial version and adapter kit. I did this after I ran it awhile after splitting it. Some metal shavings but that's about it. No heavy sludge or anything that would plug the next one right away.

1. What is the height of the hy-tran in the casting cavity the pump is located in?

Same as the transmission level. Less if headed up hill, more if headed down hill.

2. Why is it lower than the o-rings we're talking about?

It takes energy to squeeze the oil out of the gears as they mesh. The oil level is a compromise between getting enough splash lubrication and heat. The higher the oil level, the more heat is introduced into the oil as the gears mesh.

3. How can it suck air there anyways unless it's vented to atmosphere?

The pump cavity is vented to atmosphere while the suction piping is not. You could be pulling air past the shaft seal or any of the suction piping joints. With a restricted suction (plugged filter/bypass) the pump cavitates which ineffect, vaporizes the oil into small bubbles.

If you think it is a suction problem, over fill the transmission and ensure that the oil level is above all the suction piping. If it starts working, suction piping somewhere, pump shaft seal, or the filter cavity is allowing air in.

If it still does not work, plugged suction piping, plugged filter and bypass, or bad pump.

I went out and looked at my old TA housing/center section to refresh my memory. The oil levels make more sense to me again. I think I'll just put 3-4 more gallons of hy-tran in, like you said, and give it a whirl. Will a level 2-3 inches too high hurt anything? I still do not see where the pump cavity is vented to atmosphere though. It seems to me IH would have been smart to place the whole mickey mouse set-up 3-4 inches lower and solved a lot of problems.

The tube I am referring is about three inch's long and is inserted into the suction port of the pump. The tube has a lip seal on it and when you install the pump onto tractor the tube enters the counter bore in tractor. The oil from the filter is pulled right from the filter, through the tube into pump. If that seal is hard, or not positioned properly or damaged the pump will suck air. You can see the tube from filter side but can't tell a lot about it. I have seen so many of them not positioned properly and or needing replacement when the pump is replaced. They are kind of spendy so many just don't replace them. Not all pumps are the same dimensions on back side so that is why t he seal has to be adjustable by sliding on the tube.

Follow the gear train, from pump to PTO drive shaft to center of housing, input shaft is above oil level, air can get there from here. O-ring between reframe, and center section where suction tube comes from bottom of rear frame, should be a quad type seal ring. BTDT