80s Satoh Bull Tractor Hydraulic Problems

[Dave M7040]

Try and find the suction line for the hydraulic pump. Sometimes they are rubber. Other times metal sections with o rings sealing the sections.
Air can be drawn in where no oil will leak out when sitting.
Air in the system will limit lift ability.
Dave m7040

 

[rScotty]

Do you have a shop manual or hydraulic diagram for the Satoh Bull?

I doubt if it is the oil. In warm weather, 80 wt gear oil is similar viscosity to 30 wt engine oil...and that is reasonable if not optimal. Old oil that is milky or stringy has gotten water in it. Replace it. That cheap tractor trans/hydraulic oil you got will do just fine.

First hurdle is to make sure you have found the hydraulic pump, and the second is to search for a cleanable screen filter in the transmission sump. Third is to look for suction leaks in the line to the hydraulic pump.

Many tractors from that era had the hydraulic pump mounted to the side of the engine and lines for suction and pressure that came from the transmission sump and delivered pressure back to the 3pt. If the Satoh is different that way, it is the only one I've ever heard of.

Most old hydraulic problems are either a leak in the suction line to the pump, or that it has a hiddenscreen style cleanable hydraulic filter in the transmission that has gotten filled with crud and won't pass oil to the suction side.
Some older Japanes tractors had an additonal spin on suction filter, but not all. BTW, Satoh is/was a respected Japanese tractor manufacturer making their own products at one time. In the early 1980s they were roughly as popular in the USA as any other little 4wd diesel Japanese tractor.

Nothing on what you have posted here would lead me to be taking those top and bottom covers. Not sure why you did that, but it looks OK inside. But maybe I think that because I expect to find the hydraulic pump up on the engine where it works regardless of whether the clutch is in or out. Maybe Satoh really did do it differently.

rScotty

 

[kbjorn]

I drained oil as it was full of water. Will pull and paint suction hose and retuen liness redo gaskets. Could be air getting in there . Thanks

 

[rScotty]

I drained oil as it was full of water. Will pull and paint suction hose and retuen liness redo gaskets. Could be air getting in there . Thanks

Good. Do some looking around for a cleanable filter in the sump. Often it is a tubular screen under a plate. Sometimes it is the plate where the fitting for the suction hose exits the hydraulic/transmission sump. Anytime water sits in the hydraulic oil it starts to form stringy clumps of goo which will clog the screen and prevent suction flow. Easy fix.

 

[rScotty]

I found an operator manual online.

Rear Axle Housing Case Oil Replacement; Washing Hydraulic Oil Filter - satoh BULL S-630 Instruction Book [Page 52]

satoh BULL S-630 Manual Online: rear axle housing case oil replacement, Washing Hydraulic Oil Filter. Remove The Drain Plug At The Bottom Of The Rear Axle Housing And Drain Oil. After Draining, Tighten The Plug Securely And Fill In Fresh Oil Through The Oil Inlet. Remove The Filter At...

www.manualslib.com

Page 52 shows the cleanable filter under a plate where the oil is drained. It will be 100 mesh Stainless Steel or brass screen. You can make one yourself or fix the old one if bent or broken. No need for new. Sometimes they get squashed putting them back in. Just do your best with it.

Then check the rest of the suction system. If it is sucking air, you it won't find an obvious leak when running because it is sucking air in but not oil is forced out. But then when the engine is off, what you see is an area or hose or fitting that is oddly wet on the outside with dirt and oil. That is your clue that it is it is sucking air there because when the engine is off and air no longer being sucked in it allows a few drops to backflow from the pump and they ooze out due to gravity & collect dirt.

If you see a hoseclamp on an old rubber hose, that's usually it. REPLACE THE HOSE.

rScotty

 

[richnfab]

I too am having hydraulic issues on my recently purchased ( 9/1/23) Satoh 650D Bull. The seller told me that the 3-point didn't work before I bought it, and it feels like the lift lever isn't connected to anything? I was going to take the top off of the case as mattg and kbjorn had done, but I'd figured i'd start with the fluid levels. Mine did come with a manual and parts manual, and it does specify 80W for the transmission and hydraulics.

It also has an aftermarket loader on it and it raised all the way up and tilted fine when I tested it before buying, but I wish I'd scooped up a load of dirt to test the loaders lift strength. Well, it is weak and could only lift up a 500 lb plow assembly very slowly to about 1/2 of its normal lift height. The weird thing is the bucket tilt & hydraulic cylinders work as they should, it's only the loader lift arms & hydraulic cylinders that are weak.

Mine appears to have the engine driven pump mounted to the front of the engine.

So, weak/slow loader arms and hydraulic cylinders and non-functioning 3point lift, but strong bucket tilt and hydraulic cylinders.

Any advice is greatly appreciated and thanks everyone for all of the useful info in this thread. I'm new to Satoh's, and while they seem to be pretty solid, their quite different from my previous Kubota B7500 and JD 755.

 

[Mike1955]

You guys ever get your stuff working? I'm in the middle of this now, about to tear it apart further but trying to check simple stuff first. Took apart flow control, cleaned changed orings (close as I can get em?)/ Checked relief valve. Ordered guage-- be here Monday.

Manual says to let it run 30 min before testing. I have lift on 3 pt but not if its loaded. Bleed procedure poorly described in manual. But this seems to keep getting air even after being bled? Maybe I just gotta run it longer?

Inherited this tractor and it sat outside with cracked boot on tranny for years, I have changed oil/water one time. going to flush and try again. Definately milky/ cruddy at round one. Thought about putting a splash of diesel in oil but then realized i might blow up pump

Isn't learning fun?

Looking like I need a total overhaul. it seems fairly well described in manual. well actually the manual is more riddle than anything. But the line " if oil is in good condition" kind of has me at a stopping point. at 100$ an oil change, i thinking i should pressurize or vaccuum the system.

You are definitely on a roll! Good luck with the results

 

[rScotty]

I too am having hydraulic issues on my recently purchased ( 9/1/23) Satoh 650D Bull. The seller told me that the 3-point didn't work before I bought it, and it feels like the lift lever isn't connected to anything? I was going to take the top off of the case as mattg and kbjorn had done, but I'd figured i'd start with the fluid levels. Mine did come with a manual and parts manual, and it does specify 80W for the transmission and hydraulics.

It also has an aftermarket loader on it and it raised all the way up and tilted fine when I tested it before buying, but I wish I'd scooped up a load of dirt to test the loaders lift strength. Well, it is weak and could only lift up a 500 lb plow assembly very slowly to about 1/2 of its normal lift height. The weird thing is the bucket tilt & hydraulic cylinders work as they should, it's only the loader lift arms & hydraulic cylinders that are weak.

Mine appears to have the engine driven pump mounted to the front of the engine.

So, weak/slow loader arms and hydraulic cylinders and non-functioning 3point lift, but strong bucket tilt and hydraulic cylinders.

Any advice is greatly appreciated and thanks everyone for all of the useful info in this thread. I'm new to Satoh's, and while they seem to be pretty solid, their quite different from my previous Kubota B7500 and JD 755.

First things first. The way that viscosity is measured for motor oils and for hydraulic or gear oils are all different.
Rather than going into the differences, you need to drain out what it has, clean the strainer/filter, and put in some transhydraulic oil. I use John Deere HyGard (winter). Others use a variety of transhydraulic oils from any tractor supply. But NONE OF THEM is 80 wt oil. That has to be some sort of misprint. You can use 80 wt. or multi-wt. 80/90 in the front axle only. But for the regular transmission & hydraulic sump the Satoh used a very common designpump and control valve system; it will not work right with 80 wt.

Then make sure it doesn't have a suction leak between sump and pump. After that it should work if it is going to. Starting a tractor with high viscosity heavy thick hydraulic oil in cold weather is a formula for trouble. Best not do that.
good luck,
rScotty

 

[richnfab]

Thanks Scotty. I'll drain the trans oil and fill with new Hygard and clean the screen as shown on p. 52 above. I will also try sealing up the ends of the suction tube. It does appear to be a little damp near the pump end.

Can you find suction leaks like you find vacuum leaks on an engine, by spraying suspected areas with a soapy solution?

Thanks again for the great tips!

Ric

 

[rScotty]

Thanks Scotty. I'll drain the trans oil and fill with new Hygard and clean the screen as shown on p. 52 above. I will also try sealing up the ends of the suction tube. It does appear to be a little damp near the pump end.

Can you find suction leaks like you find vacuum leaks on an engine, by spraying suspected areas with a soapy solution?

Thanks again for the great tips!

Ric

The soapy water trick won't help here because the Suction Leaks are pulling air into the hose, not pushing air or fluid out. Being "a little damp" at the end of the suction hose is the classic sign of an old hose that can cause a suction leak. No way to fix it or even reduce it that I know of. Silicon goo and tightening the hose clamps does little to nothing.

Bottom line is It sounds like you are on the right track, but you will be way farther ahead to jusr replace the hose. Five bucke at NAPA plus a couple of hose clamps should do it.

It took me a long time to figure out how I could have suction leaks if I couldn't see them. In the end, it took a much younger mechanic (an army helicopter mechanic) who in exasperation took a knife and cut open an old hose from my own tractor and showed me how a pinhoe at the end of the hose can become a lengthwise split on the inner wall that can run for inches. That's where the air gets pulled in - through the pinhole and down the split. It is why tightening it doesn't help, and that is also the path that allows the oily dampness to seep out after you turn the engine off.

rScotty