Replacing hydraulic fluid

[8N51029]

Time to replace my hydraulic fluid but I want to validate a couple things here first.

The tractor is a 48 8N I bought two years ago. I doubt the fluid has been changed for many years. Thin black fluid seeps out around one axle when I run it. Thick milky fluid runs out when I remove a bolt low in the sump, e.g. the lower one holding the drawbar chain anchor or muffler clamp. The transmission is good and the lift works but growls a little when I raise it. I use it with a straight blade or box blade, and for towing a non-PTO brush mower, etc. Here in MN, I don’t use it in winter.

I won’t disassemble the pump if I don’t have to and then I’d need help or pay somebody to do it. Is drain/replace a shortcut I should avoid? How likely am I to wake Hobo’s “sleeping dog” by the drain/scrape/flush/replace method?

Given what I said about the tractor and how I use it, should I use the thinner M2C-134D equivalent UTF or the thicker GL1 or GL4? I will fill it only to the 6:00 bolt on the inspector plate. Thanks for your advice. -- Steve

 

[Tom N MS]

Already seeing a small seep and don't use in the winter, I'd go with the thicker GL-1. That's what is in mine and also my Dad has used in his for 50 years or more..

 

[Bruce (VA)]

You have two problems, neither of which will go away by ignoring them. That's the bad news. The good news is that both are more time consuming than expensive to fix & do not require a special skill set to accomplish. Plenty of folks around here have replaced axle seals & pulled pumps for cleaning; some of us have done it more than once. Regarding the hydraulics, if you have an entire day to spend on the project (maybe 2 if you're slow like me) & $150 or so for parts (assuming nothing else is broken) you can clean up & repair the usual problems & not need to worry about it for another 20 years.

Adjusting the linkage, replacing the lift piston, cam follower pin, pressure relief valve, PTO seal & dropping & cleaning the pump will get things in top working order.

Add another day for replacing the leaking rear axle seal. That's even easier to do because John Smith has a website page on that very topic.

If you plan to do any or all of these projects, let us know. Plenty of folks around here have done them one or more times & will be glad to share their screw-ups .....I mean expertise.....with you!
50 Tips

 

[ford 5600]

Start at the front of the trans. remove the bottom plug and work your way back to the small plug under the housing. then drain for 30 minutes or more. Then replace with 90w Gear oil from your local napa parts dealer they will have what you need. will work every time you need.

 

[Bruce (VA)]

I've always started w/ the small plug at the rear (tip # 3); it's easier to "aim" the flow from the smaller hole. About half of the five gallons coming out of that tranny plug usually ends up all over the garage floor!
50 Tips

 

[Tom in Aiken]

It's possible that the drain/scrape/flush/replace method will wake up the sleepy dog of gunk but I can't believe that the old milky oil is doing anything any thing in there any good.

Drain the oil and then through the inspection port (unless your going to pull the hydraulic cover) feel down around the base of the pump to get an idea how much gunk is there - you might be amazed its been working at all!! If you don't pull the pump, just keep recycling your cleaning fluid and strain it to keep from putting gunk back in. The more times you spray, wipe, strain and spray again the more you'll get out. Work at it from every angle - even the fill hole. Reach in with your hands and try to work the sludge out from around the pump base - some nice little depressions in there to gather and hold the gunk your trying to get rid of. Also pull the PTO and get what's back there - hands and an old rag will produce lots of gunk. And you get another spray angle.

Other than awkward to put back in (with a helper to guide the hydraulic lever back into position) pulling the pump is really not that big a deal (I did it and I'm not a mechanic so it can't be too hard!!). Plus you can check the values unless you decide to go all the way into the pump and do a total cleaning.

If you decide to pull the pump to really clean the sump, when you get ready to put the pump back in raise the rear end to get some room to work under the tractor. I used a highlift jack and put the rear wheels on 4x4's - but even a little more room would have been nice. When putting the pump back in, put the front end in first and then wiggle/lift the back end into position and have the bolts handy to take the weight once you get it into position. (p.s. the 80 pound pump gets heavier each time you "miss" getting it aligned and into position... A second set of hands is helpful for that too!)

 

[Drew B]

Cleaning this out is no big deal at all I just did it with my 52 8N. It took the whole day but was worth it. I did get to find out what everything looked like in there as well and to my suprise it looked all looked good, I really didnt pull out much crap at all. I did spray the whole thing down many times with all the covers off and the pump out with diesel as well. Got a good flush by useing a pesticide sprayer. As for the seals in the axel I am going to be doing that one this week I will let you know how it all goes. Really this is an easy task though.

 

[souNdguy]

go with the heavy oil for sure, if you already get leaking..

soundguy

 

[wwalkersd]

Re pulling the pump, I didn't jack up the tractor and I had no problems. What I did do:

During removal, I put a stack of boards under the pump to "catch" it when the bolts came out. Then I dragged out one board at a time until the pump fell loose.

I pulled the top cover as well, because my cylinder was leaking down quite quickly. This makes access to the pump cavity for cleaning much easier, but that top cover is HEAVY (and it's even heavier on an 8N than it is on my 2N, because of the added hardware for position control). I recommend having a helper.

Per the recommendations on this board, I cleaned up the cavity with a cheap pesticide sprayer and mineral spirits, and filtered the "catch" with an old t-shirt. Still had to dig some gunk out by hand.

During reinstallation, instead of jacking up the tractor, I used my floor jack to lift the pump into a place. I had a helper working the jack, while I was under the tractor guiding the pump and telling the helper when to jack. This made reinstallation a piece of cake.

I highly recommend getting the hydraulic rebuild video sold on this sight. The production quality and performances aren't great, but seeing what you're in for is invaluable.

 

[8N51029]

I appreciate all the advice and encouragement. And I'll think seriously about dropping and cleaning the pump, in fact I'll start by studying the manuals and parts catalog. If that's the next job, then the rear seals and brakes are next after that. I know there's a lot of satisfaction in doing these jobs for yourself. I'll be back for more help. -- Steve