640 no hydraulics

Since re-sleeving the pressure line I still have no 3pt. I tried to pump air in the dip stick hole to prime the pump (did this for about 2 minutes, twice) no 3pt still. I tried backing up on a hill so the reservoir was higher than the pump, sat there at half throttle for about 2 minutes.
Checked the plug on the top right (beneath /in front of the seat) of the reservoir cover. While tractor off there was a bit of fluid there (appeared milky, like the old fluid before I re-sleeved, bubbly as well), no change or pressure while tractor running.
Drove around for about 4 minutes to double check the hyd and tranny fluid weren’t mixing. No change to hyd. Fluid level.
Not sure what to try next, really need the tractor this weekend if possible.
Ideas or suggestions??

well.. here's the deal. you resleaved the pressure tube right?

you didn't somehow block off the suction tube did ya?

if you had blocked the pressure.. it would be obvious.. it's befor ehte relief.. so something would be spraying and loading the engine.

pullthe plug out of the top of the head of the pump and see if there is oil there... probably not id my guess.

pull off the pump manifold and check to see if you can get oil to free-flow from sump to front of trans thru the pipe. if ot.. there's your problem. if it flows out like it should.. check the manifold for debris. if none.. it's now time to check the pump

ps.. make sure she is spinning.. look at the nose with the tach disconnected/

post back

I'll have to crack the bolts at the bottom of the hyd. manifold to see if there is flow from the reservoir there.
It's a vane pump (square, no plug that I can find). Not sure how to bleed out the air??
Can I fill the plug at the top of the hyd. cover (one on the right in front of/under the seat). If that connects to the pressure line would you be able to fill the pump from it??
Also while I'm at it is this plug where you would plumb in a valve for a hyd. remote??

(quoted from post at 22:28:01 04/16/13) I'll have to crack the bolts at the bottom of the hyd. manifold to see if there is flow from the reservoir there.
It's a vane pump (square, no plug that I can find). Not sure how to bleed out the air??
Can I fill the plug at the top of the hyd. cover (one on the right in front of/under the seat). If that connects to the pressure line would you be able to fill the pump from it??
Also while I'm at it is this plug where you would plumb in a valve for a hyd. remote??

Click to expand...

here is a plug way down low near front of right running board. Remove it & see if pump will flow there. If nothing there the pump isn't pumping as there is nothing but your sleeved tube between that & pump outlet. The plug in assessory cover is well beyond control valving & therefore not exactly meaningful, as if flow there during lift command, you would have lift.

Seems to me like you have one of three problems.

1. Oil is not getting to the pump.
2. The pump is not pumping.
3. Oil under pressure is not getting to the piston

Unbolting the manifold at the transmission and watching for oil draining should confirm number one. If it dry, you have a blockage between the reservoir and the manifold. I doubt that is the case, That tube is about 5/8" ID and a direct shot at the reservoir. Not easy to block. But you've got to check it.

If you have oil draining out of the manifold, I would take the manifold off and make sure its open. Check the bottom of the pump. Also run a long rod through the pressure tube. It should go several inches beyond the length of the transmission. That would check to make sure the pressure tube is not blocked.

While the manifold is off, use a rubber tipped blow gun and put some air pressure down the pressure tube. Move the control lever. Does the 3 pt react at all? If yes, you are open and no blockage beyond that point. If is doesn't move, I don't think it means anything. You may not have enough pressure to make things work.

Another option to try. On the bottom of the center section (hydraulic oil reservoir) there is a small plate. Its on right side just behind the transmission. About 2" X 3". Under the plate is a cavity that houses the pressure relief valve and and access to the tube that takes pressure to the top cover. It is also where the transmission pressure tube goes. If you pop that plate off, you can probably see the area where any excess epoxy may have gone. Clean it out and run a rod through that tube to make sure it is clean. That plate if often stuck on really good. Take your time. Also, the replacement gasket is only available from CHN. Might want to order one before you try this. Remember, no puckey on that gasket, put it on clean and dry.

If all this checks out, I'm thinking a pump problem, or something is blocking one of the valves in the top cover. I doubt its the pump. Good news is that the top cover is not that hard to work on. The hardest part is lifting it off and getting it back on.

Keep us posted.