Southern MN | Hydraulics on the 70 series New Hollands, based on posting to this newsgroup, require rebuilding when they start under-performing. I'm at that point. The two problems I'm trying to solve are:
1. High pitched squeal when remote is left in the raise position when operating my sprayer boom level controller.
2. Lack of power and/or flow to fold up my sprayer booms or the wings on my ridge till cultivator.
I have the service manual and plan on tearing apart the hydraulic remotes and replacing missing/worn o-rings as needed. Is there more to it than just o-rings? Before I tear into, I'm wondering how I order new o-rings when I don't see them on the parts listings. Is there a kit with a part number?
As far as the high pitched squeal, I did find a small note regarding it occurring if the remote is held in the raise/lower position, but I'm not doing that. I attached a picture of that note, and one of the hydraulic schematic.
I am basing my need and ability to tackle this issue based on a former post by MJS:
MJS - 1/19/2013 19:32
Check that the o rings are not gone on the primary and secondary shuttle valves in the remote valves,if they are gone it will reduce the hydraulic flow dramatically.
One of them is under the detent cap and has two o rings,the other is behind the valve stack with one o ring.The one behind can be accessed without removing the valves but you might need someone with small hands,just be carefull though as there is a ball in there,the valves are angled forward so it shouldn't, fall out.
There is also one under the left solenoid valve cover on the 3pt linkage valve and on the back of it.
The valves are recessed and take an Allen key,The o rings are a white high temp. Type. The later models have a backing ring on the o ring and should last longer,the early models don't .
I just done mine and there wasn't one of the 12 o rings left,unfortunately I had already gone through the process of converting my air seeder to a PTO pump.
 (HydraulicNoise.GIF)
 (HydraulicsRaisePosition.GIF)
Attachments
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 HydraulicNoise.GIF (5KB - 551 downloads)
HydraulicsRaisePosition.GIF (46KB - 557 downloads)
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New Holland 8770 Hydraulic Remote Rebuild Process
