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Subject: 8n hydraulic lift is very weak

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JohnB    Posted 08-05-2017 at 21:24:19 [URL] [DELETE]        [Reply] [Email]  
  • 8n hydraulic lift is very weak
  • Sorry for the long post . . .

    It all started about 3 months ago. I was using the pond scoop on the tractor ('48 8N) when I noticed that the lift became somewhat weak and would "creep" to the up position - even if I had the touch controller down. It would only do this when the scoop was empty because the added weight of the dirt was too much to allow it to creep up.

    I removed the top plate to investigate and found a chunk of rubber (actually it was part of the piston seal) lodged in the inlet (or exhaust) valve of the pump. Obviously this prevented the hydraulics from working correctly. I took this opportunity to replace the piston seal and adjust the linkage using Zane's fixture.

    Once everything was buttoned up, the position control worked flawlessly . . . until I put a load on the arms (like a finish mower, blade, etc . . . ). Now, it will lift about 1/2 way up, then stop lifting altogether unless I give it some gas to increase the pump speed.

    Here is what I have looked at so far: 1. The piston/cylinder is not leaking. It will hold the mower up for a week. 2. I cannot feel any oil getting past the safety valve. 3. When running it and looking into the inspection cover, I don't see any leaks coming from anywhere . . . just a swirl of oil as you would expect.

    My next move is to pull the pump and go through it to make sure something isn't awry. Aside from that, is there anything else that could cause this?

    Tim Daley(MI)    Posted 08-06-2017 at 06:43:20 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8n hydraulic lift is very weak
  • There are other adjustments you can do---got the I & T F-04 manual handy???

    Tim Daley(MI)

    JohnB    Posted 08-06-2017 at 09:56:44 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic lift is very weak
  • The only change I made using the Zane's jig was changing the position control nut about 3/8" (it was very close from the get-go) and the lift worked great before the pump sucked in part of the seal.

    However, you bring up a good point: maybe it's worth double checking the adjustments. I'll re-read that section in the FO-4 manual.

    BlasterStumps    Posted 08-05-2017 at 22:14:12 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic lift is very weak
  • first I would take a look at the cam follower pin. You should be able to see it through the inspect cover on right side using a light and mirror. If it is badly worn, may need to replace it.

    JohnB    Posted 08-06-2017 at 09:57:46 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8n hydraulic lift is very weak
  • The cam follower is brand new. I replaced it when I had the top off.

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