MF-35 Hydraulic System Leak Down

After shutting the engine off or pushing the clutch all the way down the lift on this tractor will sink down within 5-10 seconds with a 5 foot cutter attached. My other FE-35 takes much longer to settle.

The previous owner told me that the system has "hydraulic oil from work" in it. He could not tell me anything more about the oil except that it is definately not GL-1 90W as I have been told these tractors use. Is GL-1 90W the right oil for this tractor?

Today I drained about half of the oil, removed the right inspection cover and had a look see. With the engine running and the lift with mower attached raised all the way up, there is a small but steady stream of oil leaking from the lift cylinder. There is also turbulance near the right rear of the pump. Might the turbulance be normal oil exhaust from the exhaust valve? Also, considering that the oil is probably too thin (It is draining now), how much cylinder leakage is acceptable?

Finally, on early N series Fords recommended practice when re-ringing a lift cylinder is to replace the piston with the later NAA cylinder, which uses the later design O-ring seal rather than metal rings. Is there an improved design piston available for the MF-35 or should I just hone the cylinder and replace the rings if cylinder/piston service is indicated?

Thanks in advance.

Dean

I noticed your comment about steel rings vs rubber oring. Having had both, I always thought that Fergie was one up on Henry with his 3 steel rings..... didn't know that the early vintage Fords had them also course the NAA...Ford's law suit buster, "had" to be different.

But I really think the difference was price. I personally would rather have the steel rings. My MF-35 is a '64 and still has the orig rings. Yes I use 90 GL-1 and when you shut the tractor off the 5' hog drops in about 15 seconds.....but that doesn't bother me enough to rip her all apart.....doesn't seem to affect functionality; being it's live pto may make the difference in it not being a bother. Course since the pump is driven off the transmission, it does work differently than the Ford, like you have to let the clutch half way out to get the deck to respond to the lift lever being up, whereas the Ford is up as soon as the engine lights off.

Mark

That's good information. I'm just trying to decide whether to get into the lift cover or not. I expect that the use of the wrong oil is contributing to the leak down but do not yet know just how much effect this will have. Plugs are still out. I usually let them drain for several days when I do not know just what was in there.

Ford used steel rings through 1952. They changed to a single neoprene O-Ring with leather back-up washer in 1953 and recommended practice when servicing an early N tractor needing cylinder/piston work is to replace the cylinder and piston with the later design. It does seal much better.

I note that the later MF-135s used an O-Ring design but it is a larger diameter so not compatible with my tractor. Just thought I'd ask the MF folks whether a a retrofit O-Ring piston is available for the 35s.

Maybe, I'll pull the cover, hone the cylinder, replace the rings, and have a good look see while the oil is drained. It will give me the opportunity to flush everything out real good.

Thanks again.

Dean

Hope things go well for you.

Mark

• Big Dean's Massey Ferguson web site

I have already inspected the system via the right inspection cover. There is a small but continuous leak from the cylinder and some turbulance near the right rear of the pump. The system has generic hydraulic oil rather than the recommended 90W GL-1. The oil is draining now and I will replace it with 90W.

How much leakage from the cylinder is acceptable?

Can the relief valve be changed without removing the lift cover?

Thanks, in advance.

Dean