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1966 770 oliver hydraulic problems

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Ron force
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PostPosted: Sun Dec 10, 2017 7:36 am    Post subject: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote



I posted this before, but good people asked questions I didn't have answers for, so now I have some.1966 770 Oliver with dual hydraulic capabilities has no pressure or oil flow on either side lift or drop sides,I have been told the electrical wiring for the cylinder controls can be eliminated without affecting the the manual controls.( Question #1 is this correct ??) the tractor was on a farm feeding cattle for many years, so when I took over the farm I checked the hydraulic oil reservoir and it was 5 qts low on a 9.5 qt capacity. I have taken the foot platform cover off and with the tractor idling the shaft that runs the pump and PTO is spinning and it sounds like the hydraulic pump is spinning (question #2 could the problem be in the control valves??) (question #3 if I remove the control valve /reservoir what can I expect? the concern here is how the pump is connected to the control unit. if all discussions lead to a pump replacement how do I get it apart? I have a operators manual ,and have ordered a service manual, Any help or guidance would be appreciated
 
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ADB-Ia
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PostPosted: Sun Dec 10, 2017 6:45 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

You can run the hydraulics without the hydroelectric hooked up. The operator manual explains how to set up for one way or two way cylinders. It also covers how to set the restrictors in the swivels on each side. Make sure those are set correctly first. Next I would try to determine if the pump is generating pressure. My experience with those units is that if the pump goes, it dumps all the oil into the transmission. So if it had oil in it when you started, even though it was low, the pump probably wasn't shucked. Does it squawk the relief valve when you operate the lever? I think there is a plug that you can use to hook up a power beyond where you could check for pressure below the valves. You separate the reservoir from the base to access the valves. I believe this can be done with the unit still on the tractor. You pull the whole hydraulic unit off to get to the pump. First, since the pump runs off the pto shaft that runs through it, you have to pull the pto shaft out the back - remove the whole pto unit. Then you have to remove the shift lever. Care must be taken to not let the springs escape down into the transmission from the base of the shift lever. Next remove the whole hydraulic unit from the transmission housing. The pump is then removed from the bottom of the unit. If you are getting the Oliver service manual all this is covered.
 
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Centerplate
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PostPosted: Tue Dec 12, 2017 6:23 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

ADB has given you a lot of information. You should be able to get near 1000 psi on a real good pump. The pump could be very worn and/or have a cracked center. That is why you are losing oil. The relief valve is the large nut in front of your feet. You should drain the oil before you attempt to increase the number of shims to increase the operating pressure.

I have parts available to repair your pump if you need.
oliver pump parts

 
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Ron force
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PostPosted: Tue Dec 12, 2017 7:06 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

ADB I have all four 1/2 pipes removed from the base plate and installed pressure gauges and no pressure, then removed the gauges and no pressure or oil flow at all regardless of where I move the control levers.I tried to remove the plug on the left side between the pressure and return ports to check for pressure but the plug wont move the center is stripped out, I believe there was oil in it when I started just because the book says the capacity is 9.4 quarts and I added 5 quarts to get it full. It has been full for 3 weeks now and the oil level has not dropped.The pressure relief valve is according to the book of the not adjustable kind and it does not make any noise, is it shim able?I have heard about the springs under the shifter (thanks for the heads up} I assume they are for the detents in the shiftier rails.I guess my next step is to remove the oil resivior to see what the control valves look like, and do believe I am headed towards a pump replacement, your thoughts??
 
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Ron force
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PostPosted: Tue Dec 12, 2017 7:11 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

thanks for the reply, I am sure I will be calling you once I am sure what I need.
 
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ADB-Ia
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PostPosted: Tue Dec 12, 2017 8:06 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

It has been 10 or 15 years since I did mine on my 880. I had to rebuild the pump on mine. I am working from memory on the process. I got the Oliver service manual on CD when I did mine and followed it. It is likely after all these years that the pump will need to be rebuilt, but if your oil level is not dropping I think your problem is more likely in the valves than the pump. I say that just because it seems unlikely that the pump would generate 0 pressure even if badly worn. And even if the relief valve were stuck completely open, you should get some oil through the system at very low pressure. Just my thoughts. I would quickly transfer you to Centerplate as he is much more experienced with these units than I am. I always enjoy the challenge of figuring things out. That is the fun of working on these old machines.
 
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Ron force
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PostPosted: Tue Dec 12, 2017 1:18 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

Thanks for your help anyway, I had a great conversation with him today, thanks again CHEERS
 
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Ron force
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PostPosted: Wed Dec 13, 2017 2:54 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

After our conversation the other day I drained the hydraulic unit then pulled the pressure relief valve cover then the spring, but no christmas tree came out. So I started the tractor briefly to see it the Christmas tree would come out there was oil pumped out maybe a coffee cup full until the pump ran out of oil. of course I shut it off. Now I think the pump is working but how do I tell if the christmas tree is still in there, I can see a 1/4 hole in something in there maybe 3 inch in but not sure what it is. so how do i know if its in there. Also the oil I drained was milky so i assume there was water in it. Now what??
 
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ADB-Ia
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PostPosted: Wed Dec 13, 2017 6:35 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

Sounds like the plunger (christmas tree) is missing. The spring holds the plunger against the seat which threads into the housing inside that port. That is the hole you are seeing in there.
 
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Ron force
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PostPosted: Fri Dec 15, 2017 5:28 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

yes I need a plunger now the question is where do I get one. and does the seat have to matched to work right??
 
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Ron force
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PostPosted: Fri Dec 15, 2017 10:31 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

found the plunger got it out with a magnet
 
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greg oliver
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PostPosted: Fri Dec 15, 2017 12:37 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

Nick, I tried to message you on F.B. about Ron's pump problem.
 
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ADB-Ia
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PostPosted: Fri Dec 15, 2017 3:39 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

Looks like you can still get parts from AGCO. agcopartsbooks.com - Under White Oliver, 770/880. I just had to page through till I got to the hydroelectric page. Maybe there is a better way to search but I don't know how.
 
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ADB-Ia
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PostPosted: Fri Dec 15, 2017 3:48 pm    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

If you have all the parts the relief valve should be working if the spring / plunger / seat aren't damaged.
 
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Ron force
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PostPosted: Sat Dec 16, 2017 6:28 am    Post subject: Re: 1966 770 oliver hydraulic problems Reply to specific post Reply with quote

removed the hydraulic unit yesterday with help on a phone call to centerplate,I have removed the pump and disassembled and the inside of the pump is real good no marks on the sidewalls or the centerplate, bearings and gears are in great shape. So now I guess I need to figure out how to test the pump and the control valves, they look clean also, but not sure just yet of the operation. When I did get the plunger out it had a somewhat shinney circle in the nose area where it would have meet up with the seat so I believe it was in position. Just dont see yet where the pressure is going, any ideas are appreciated !!
 
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