Hydraulic issue

   / Hydraulic issue #1  

macecase

Bronze Member
Joined
Sep 27, 2012
Messages
97
Location
Princeton, KS
Tractor
1965 John Deere 3020 Diesel and 1975 John Deere 4630 Diesel
I have a Ford 8N. Works good but the hydraulics are soft and sometimes don't work.

I took off the inspection plate and ran the lift arms with a implement attached. They lifted a bit (not as high as I would imagine they should). There was a steady stream of oil coming from the top.

So, I am guessing something is leaking from the hydraulic ram cylinder. I am hoping to get some advise to make sure I am thinking correctly before I go digging.

Aside from an obvious issue if the Ram cylinder housing ends up being cracked, I would think replacing the piston (if old-style 3 ring) and/or the o-ring and backup (felt/leather) ring would do the trick.

Is that right? I know I will need to get new gaskets for the top plate, etc... That is no big deal.

The pump seems to be pumping. I also have milky fluid so I will change that. I already have a replacement boot for the shifter to help from this happening again.
 
   / Hydraulic issue #2  
allow 4 hours for this job.

have a top cover gasket, plus the 3 small gaskets under the hyd cyl.

i reccomend the NAA piston with oring and new weophrene bacup cupped washer. tip.. piston has open end and closed end. closed end goes into cyl mouth.. open end faces out for dogbone to ride in. with piston on table, closed end up, cup shaped backup washer goes on first.. then oring. don't twist eiher.. use some crisco or grease for lube. old style leather backup washer will work too.. soften it up in a cup of hot water first.. use 2 teaspoons to walk it on.... there may be a smooth and a rough side.. I put smooth to the oring.. though really.. it matters not..

when you pull the top cover, put some compressed air tot he oil hole onthe side after disassembling some linkage to clear the cyl mouth.. thent he piston will pop out in your hand.

there will be a cam follower pin that rides a cam on the rocker onthe rockshaft.. sometimes the cam is worn in profile, and the pin is usually worn in half. use a socket and punch to drive the pin out and repalce with a new one. socket backups up the thin and hard to repalce linkage you are driving the pin from. in a pinc an old broke drill bit stem with a llil grinder magic makes a good pin.. or get one from your dealer. the cam can be welded up using the profile as a witness.. then grind to contour match.

adjust as per fo4 manual states.

DO change the oil

when putting over back on,, guide control arm into slotted lever on pump.. make sure it moves freely.. it may be gritty from old oil. I personally like to drop the pump and ( pto shaft ). and clean the entire rear casing.. your call.

if you do, get a new lower gasket and pto flange gasket. cut or get another side cover gasket.. or rtv the side over.

no rtv or other gasket goops on ANY of the other gaskets.

if you totally R&R the top cover and pump, allow about 7-8 hours.. can do this all via cookbook with a few hand tools and cleaners..
 
   / Hydraulic issue
  • Thread Starter
#3  
Thank you for the detail reply!!

I will refer back to this when I tackle the project. Now, just needs to get a touch warmer!

Thanks again.
 
   / Hydraulic issue #4  
lookin forward to it.
 
   / Hydraulic issue
  • Thread Starter
#5  
lookin forward to it.

Just got to it due to a break in the weather.

I took it apart and put a new piston in, etc.

While putting it back, the draft control linkage has thrown me for a loop and thought you might help.

My question is: The part appears in the books like a single piece. I found the spring in the hydraulic oil when I took the cover off. So, I'm guessing my part broke.

The rod with a bushing and spring isn't connected to the back part. It looks like the assembly is broken. Is it?

IMAG0229.jpgIMAG0230.jpg

ALSO: I cannot get the hydraulic oil drains off. I have a wrench but they are not budging. Any tips?
 
   / Hydraulic issue #6  
on an 8n..

there is a pipe plug under the diffy.. a bung plug under the pump.. and a bung at the tranny.

if the bungs are rounded.. an air chissle will spin em out..or weld a big hex nut tot he plug head and spin em out with a proper wrench.

now.. hit this web page I'm posting and scroll to the bottom of the parts. John smith has some real good used parts. check out his draft parts assortment. the pics will let you see what it should look like. my screen is sooo small i can't make out your 2nd pic well. in any case.. hit the smiths site and take a look.

Hydraulic and Lift Parts For Sale
 
   / Hydraulic issue
  • Thread Starter
#7  
Thanks for the tips. I emailed him for a new part price with shipping.

Thanks again!
 
   / Hydraulic issue #8  
sorry i couldn't see that lil pic well enough to tell you.. but john smith is a great guy.
 
   / Hydraulic issue
  • Thread Starter
#9  
Just ordered the part and he is shipping today!!!!!
 
   / Hydraulic issue #10  
john's a good guy.. I've bought many things from him over the years. he's a great source of info too.
 
 
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