What is normal for a FOrd 8N?

John Ayres · Jul 7, 2014

I am running a 5 foot bush hog driven off the PTO of my Ford 8N with the PTO clutch and using the three point to lift it. The hydraulics only holds the bush hog up for a few seconds once the PTO is disengaged with the clutch or just left stationery and PTO disengaged. The hydraulic piston under the seat has been replaced and new seals and this did not fix anything. Is this normal as I had thought it should hold it in place for longer than this? Thanks, John Ayres

Bruce (VA) · Jul 7, 2014

Check out tip # 16.

How did you determine the lift cylinder/piston was bad? Did you observe the oil leaking down from the top?

Did you check for a leaky pressure valve?
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Dave in Wyoming · Jul 7, 2014

With the info you gave, I would think it"s a leaking Pressure relief valve.
Dave

KCM · Jul 7, 2014

In short, it is not normal. The lift should stay up anywhere from a few hours to a few days depending on the wear in the pump and lift cylinder. If it goes down that fast, you have a major leak somewhere. Follow the advice of the previous posters and track down the problem. Sounds like the lift cyinder is out of the equation since it has been rebuilt.

FLAcharlie · Jul 7, 2014

Besides fixing your hydraulics, you could also just get limiting chains, that hold the brushhog at the right height, so no need to use the hydraulics. I wrestled with this when I first got my 'N, but now all I do is mow, so don't currently need the hydraulics. Google on "8n limit or check chains"

John Ayres · Jul 8, 2014

Thanks to all on this. Since the piston and seal were replaced and it stayed the same I am inclined to suspect the pressure relief valve. Tip 16 does not address the procedure to replace this. Is this a complicated job?

Tom N MS · Jul 8, 2014

Drain hyd fluid from rear sump or nose it down in a ditch to make the fluid run forward(Caution: if front tranny seal is bad u will soak your clutch like I did then I had to replace the clutch) I remove the pto shaft to gain a tiny bit of working room inside..I work from the left side(remove the plate with the pto engage/disengage lever) Use 11/16" boxed end/open end wrench--I use standard wrench-some folks cut and bend wrenches....unscrew old one and screw in new one..tiny strokes usually involved but once broken loose, you can normally reach in and finish removing by hand...HTH

Bruce (VA) · Jul 8, 2014

" Since the piston and seal were replaced and it stayed the same I am inclined to suspect the pressure relief valve."

Excuse me, but you are about to make the same mistake twice in a row.

There is a reason why I asked these questions:

How did you determine the lift cylinder/piston was bad?

Did you observe the oil leaking down from the top?

Did you check for a leaky pressure valve?

The point of tip # 16 wasn't to tell you HOW to fix the problem......but to tell you to DIAGNOSE the problem BEFORE you start replacing parts.

It's not that hard to pull an inspection plate & see if you oil leaking down from the top w/ a load on the arms. You wouldn't be the first guy to replace a cylinder in a bad piston. Or failed to detect a blown gasket w/ an internal leak.

If you do not see oil leaking down from the top, then test the pressure relief valve before you spend time & money to replace it. Because there are still other causes of the problem.
75 Tips

G6 at Snook, TX · Jul 8, 2014

I agree with Bruce. Pull the side plate with the dipstick and watch for the leaks. If it is from the relief valve on the pump great, but it could be from cylinder even if it has been fixed in the last year. What harm do you have in pulling it? A few minutes of observation and a few minutes worth of bolts to pull. Also, I would do it after working the tractor hard for an hour or so mowing to make the fluid thin up and more easily reveal the leak.

What is normal for a FOrd 8N?

John Ayres

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Bruce (VA)

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Dave in Wyoming

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KCM

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FLAcharlie

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John Ayres

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Tom N MS

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Bruce (VA)

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G6 at Snook, TX

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