just brought home a previously enjoyed 966 IH tractor and guess what the pto does not work any ideas? thank you Tom

Check PTO oil pressure.

Yea, Probable same thing i just fixed on a friend's 806 . The as i call them the micro mini pin in the valve . To fix remove the draw bar support from the tractor , remove the linkage from the top of the PTO control valve and on the bottom of the PTO unit below the valve you will find a PLUG it will take a 1 inch thin wall socket , using compressed air clean around the top of the valve stem and around the plug , Next place a clean five galloon bucket under the plug and remove the plug and catch the valve as it falls out And as fast as you can put the plug back in as not to lose to much oil . If the valve comes out in two pieces then it is the pin if the valve is in one piece then you may have to go deeper . Now this is under the assumption that the three point is working and you have steering and brakes. If you do have three point and the steering and brakes and the valve is in fact in one piece then more then likely the clutch pac is toast . Now this is where you need two things that i am betting are not in your tool box. (1) an hyd. pressure gauge that can read 600 Lbs. (2) the special fitting to install in the test port so you can reset the clutch pressure . Clutch loc up pressure for a 966 should be between 230 -245 lbs. With the hyd. oil at operating temp. of 150-180 degrees. The pressure is set by screwing the valve stem into the top nut whit the PTO running , There is a small hole neard the threads that you use to turn the stem while setting pressure and there should be a Half nut to lock the stem to the top nut when done.

Like the Tractor Vet says, but you can check for a broken pin by removing the nut around the top of the valve stem. If you can pull the valve stem out of the PTO housing the pin is broken.

Tractor vet, I pulled control valve out the mini pin was sheered replaced it, reassembled unit still did not work,checked pressure 0 pressure so I pulled pto unit out pulled clutch pack everything seems to have minimal wear so I didnt see any reason to preceed with out asking for more input. Thank You, Tom

Did you have a fitting to install in the test port and the gauge . Did you screw the stem into the square top nut . IF yes to all of these questions then next is what is the condition of the suction tube and the seal on it . Next is to look at the pump on the pto . From there it would be the piston seal on the piston BUT here now you are going to have to make up a tool to compress the clutch pac return spring and get deeper in to the seal rings on the clutch drum and the condition of the main housing as to the ware where the seal rings ride . Also one must be careful as not to damage the pickup tube in anyway . So if you are going in that deep then ya might as well do a total rebuild and install the HD clutch pac . Only other thing is to inspect the input shaft and couplers but in all the PTO's that i have worked on i have never seen a stripped out shaft or coupler. ONE other thing here do you have atleast and I T manual if ya don't then get one and set down and read it . As since i am on this end of a IDIOT BOX screen i can not see just what you are doing or trying to do or what is going on.

I do have a IT manual But I figured sometimes a little experience goes a long ways. As far as the suction tube the seal is marginal There is nothing wrong with the pto drive shaft or couplers The pump gears seem to be good dont seem to have a lot of wear. I pulled the piston out after I removed keeper and spring Used a minimal amount of air pressure to remove piston seemed to be a little leakage around seals By the way I am not new to farming and equipment repair I have 35+ years in the maintenance field but sometimes its easier to pick someone else brain for once Thank You, Tom

Well , I told ya all that i can as there is not much to them units so if everything is as it should be and the pick up tube is snug in the clamp the tube does not have a flat spot and in the correct position and does not flop around as this will cause the seal to suck air as it just sorta sets in the bore and the pump is good ya got the valve put back together correctly don't know what else to tell ya as like i said i CAN'T see it. It takes me about two hours from the time i start with draining the oil to the time it is running in the tractor again. Did ya check the brake piston's ? last thing as to where the oil pressure could get dumped . Oh if your going to replace the teflon seal rings on the clutch drum it helps if ya soak them in hot water - oil to warm them up then use a piston ring compressor to shrink them back into the seal ring groves . and be care full when reinstalling the clutch drum back into the housing so not to damage the seals . I use white grease on theses .