Farm Equipment - 8000 series hydraulics help

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8000 series hydraulics help

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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=121815
Printed Date: 20 Sep 2025 at 2:51pm
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Topic: 8000 series hydraulics help

Posted By: timmiso
Subject: 8000 series hydraulics help
Date Posted: 11 Apr 2016 at 8:53pm

Got a new to me 8070 - nice tractor, to go with my 7000, which was my first tractor I got when I started farming.

So I have an 8070 hooked to my planter, the blower fan needs 8-12 gpm to get the correct setting, I'm only able to get to about 1200 rpms on the blower, when I need to get to 3400. All remotes act similarly (there's 4) I do get alot of noise at times. I'm going to start by pulling filters, and then will check out the compensator valve. Could somebody help me out with anything else to check on. People tell me to get real AGCO filters for it vs the aftermarket. Basically needing a breakdown on how this system works, and what else to check. I'm know some about pfc systems as I just went thru this with my 5088 a couple years ago, but just enough to me dangerous. I'm leaning towards compensator valve or plugged signal line, as I'm getting some variation in flow according to my monitor that watches fan speed. Thanks!

Replies:

Posted By: darrel in ND
Date Posted: 11 Apr 2016 at 9:04pm

did you adjust the flow controls at all.....? Darrel

Posted By: DrAllis
Date Posted: 11 Apr 2016 at 9:05pm

Must have both hoses connected to tractor outlets. Cannot have a return hose stuck back into rear end case. Must tighten down detent kickout screw to keep lever engaged, or there's a 3 GPM leak in the system. Cannot tie the lever in with a bungee strap. AGCO filters only and installed the correct way.

Posted By: timmiso
Date Posted: 11 Apr 2016 at 9:27pm

What is the reasoning for both hoses in the remote - this could be part of the problem as I'm dumping into the reservoir. Not trying to be smart - just want to learn. Flow controls make some difference, like going from 800 to 1200, but not enough to get into range. Flow controls seem odd, if I turn to the right it will increase speed until it starts over, the case I had before was 1/2 turn from max to min on flow control - how do these knobs work on the allis? Also where is detent screw and 3gpm leak - sorry I have no manual for this one yet, came off truck on Friday. Thanks!

Posted By: DrAllis
Date Posted: 11 Apr 2016 at 9:34pm

Not returning the oil thru the couplers causes all kinds of issues with this gravity charged system. There is no "charge" pump whatsoever, so when you return to sump, that oil was intended to be charge oil. Remove the rubber plug at the rear of the valve you intend to use and reach down in there with a flat blade screwdriver and tighten the screw down so it can't kick out. A pocket screwdriver is too small. Just a little bigger than that and you might have to grind down the sides just a bit for a good solid fit.

Posted By: DrAllis
Date Posted: 11 Apr 2016 at 9:37pm

The flow control valves are only 180 degrees rotation, although you can turn them 360 degrees.

Posted By: timmiso
Date Posted: 11 Apr 2016 at 9:48pm

Ok got it - so by dumping into case I'm starving my pump - it's only 45 out so oil isn't really flowing well which would cause my noise. With the oil that cold it'd be really hard to pull that kinda volume from the reservoir. I'll check it out - thanks!!

Are the remote returns restricted very much? The planter manufacturer wants it returned to sump, but they also talk about return pressures exceeding 250 psi.

Posted By: SteveM C/IL
Date Posted: 11 Apr 2016 at 9:53pm

Those filters in the sides of rear hsg are side specific and the hardware has to be installed correctly too.Pay close attention when removing or have a dealer copy the pages for servicing them.Have to buy AGCO to get the O-rings included.Think there is threaded holes in plates to run bolts in you take out to "pull" plates.Hopefully the "doors" are in place and working so you don't dump the whole rearend full of oil when pulling filters.LOL!

Posted By: DrAllis
Date Posted: 11 Apr 2016 at 9:57pm

If you have good operating couplers and tips, I don't think there's a problem, especially once the oil is warmed up. You can case-drain your fan motor back to sump, but not return flow. Allis-Chalmers pioneered this design hydraulic system and that was one of the quirks....no real charge pump, just gravity. So proper oil levels (top sight glass, not bottom) and warm oil temps help make it work better. To think John Deere finally had a system like this 20 years later on their 7000 series is kind of funny.

Posted By: darrel in ND
Date Posted: 12 Apr 2016 at 4:20am

Look under the seat, there should be at least one flow control there with a decal showing the rabbit and turtle. That may help you. And just to double check what Dr said, very important, that case drain goes back to sump, but both pressure and return plugged into coupler. Make sure that your stand by pressure and high pressure are at the very high end of the specs. Darrel

Posted By: Aus D19
Date Posted: 12 Apr 2016 at 5:03am

would it be possible to plum into 1

Posted By: Aus D19
Date Posted: 12 Apr 2016 at 5:15am

Would it be possible to plum into 1 inch lift circuit return line to bypass remote outlet restriction,for fan motor return line

Posted By: DrAllis
Date Posted: 12 Apr 2016 at 6:26am

Never done that before, but I don't know why it wouldn't work....the end result is the same with even less restriction.