80s Satoh Bull Tractor Hydraulic Problems

[richnfab]

Scotty,

Both hydraulic lines are steel, from pump to hyd tank.

I checked the hyd fluid level today and its full, to within 2" of the threads of the fill plug. I also put a clean paint stick in the fill hole, to the bottom of the hyd tank/reservoir, and the fluid is clean, clean, and looks brand new. Even wiped it with a clean white rag and no sign of dirt, color, or stringiness from water intrusion.

I then pipe doped the fill plug threads to keep water out. I do have new fluid ready if needed, but I sure would hate to waste whats in it. My manual calls for 13.1 quarts, or about 3.25 gallons.

I obviously haven't pulled the filter screen yet and the only replacement filter I can find is $239.00 + tax/shipping for the Satoh Bull.

Since the screen and access/drain are on the lower side of, but not the bottom of, the hyd tank, I'm assuming any gunk or debris will remain on the bottom of the hyd tank. Could i do a brief test run of the hyd pump with the screen pulled, access cover/gasket replaced, and fluid topped off? With no obstruction on the suction feed, i.e., filter screen removed, the hyd pump should raise and tilt the loader quickly and actually have lifting power. My issue is a lifting/tilting power issue with a load on the bucket. It raises and tilts fine, albeit a little slow, empty and unladen. Assuming the filter screen is in good shape, then my next suspect would be the hyd pump.

I'm just asking your thoughts on the above test, and I don't plan on trying it as I realize I could potentially grenade the hydraulic pump if some solid debris were to get pulled through it.

Next thing I plan on doing this weekend is to cleanup the 4 ends of the hyd pressure/suction lines, and the scuff them and apply copious amounts of blue permatex and allow to dry for 24 hours and then test to see if that healed any suction leaks.

Thanks again!

 

[rScotty]

Scotty,

Both hydraulic lines are steel, from pump to hyd tank.

I checked the hyd fluid level today and its full, to within 2" of the threads of the fill plug. I also put a clean paint stick in the fill hole, to the bottom of the hyd tank/reservoir, and the fluid is clean, clean, and looks brand new. Even wiped it with a clean white rag and no sign of dirt, color, or stringiness from water intrusion.

I then pipe doped the fill plug threads to keep water out. I do have new fluid ready if needed, but I sure would hate to waste whats in it. My manual calls for 13.1 quarts, or about 3.25 gallons.

I obviously haven't pulled the filter screen yet and the only replacement filter I can find is $239.00 + tax/shipping for the Satoh Bull.

Since the screen and access/drain are on the lower side of, but not the bottom of, the hyd tank, I'm assuming any gunk or debris will remain on the bottom of the hyd tank. Could i do a brief test run of the hyd pump with the screen pulled, access cover/gasket replaced, and fluid topped off? With no obstruction on the suction feed, i.e., filter screen removed, the hyd pump should raise and tilt the loader quickly and actually have lifting power. My issue is a lifting/tilting power issue with a load on the bucket. It raises and tilts fine, albeit a little slow, empty and unladen. Assuming the filter screen is in good shape, then my next suspect would be the hyd pump.

I'm just asking your thoughts on the above test, and I don't plan on trying it as I realize I could potentially grenade the hydraulic pump if some solid debris were to get pulled through it.

Next thing I plan on doing this weekend is to cleanup the 4 ends of the hyd pressure/suction lines, and the scuff them and apply copious amounts of blue permatex and allow to dry for 24 hours and then test to see if that healed any suction leaks.

Thanks again!

Rich, it sounds to me like you have a good mental picture of how the hydraulic system is working. I agree with everything you are seeing and saying including the test - and am against doing it for the same reasons you say. Also I prefer pipe fittings to have a good metal-to-metal seal without sealants - but that is being nit picky. I sometimes use permatex like that too. Being careful to keep it external to the flow - but sounds like you know that. I confess to even having used silicon gasket maker as an external "paint" on suspicious suction fittings.

Several of the other smaller Japanese tractors from that era were made without a replaceable spin-on filter in the suction line - maybe for economy. Many only had the single strainer in the sump. Later on, it became popular to add a spin-on filter in series via an outboard mount and still retain the strainer. It is also a common design to see that a strainer cover is multipurpose as you describe. It can retain the strainer, seal the sump, and also has a fitting for hard piping from there up to the hydraulic pump.

I'm not surprised that the bottom of the hydraulic sump is clean. That is a srong suction and trans.hydraulic fluid is a great cleaner. It is common for all the crud to end up as a coating on the outside of the strainer screen. You may be surprised at how thick the layer is there. The marvel is that fluid still gets through. So I encourage you to pull the strainer, clean it carefully with a toothbrush and reinstall. No need to waste good hydraulic fluid - you can drain it, and then either filter it through some flannel or an old cotton sock - or my favorite way is to just let it set until it settles - then decant or siphon off the clear fluid and re-use it. No point to replace the fluid with new until we find the problem and get enough flow to purge the system.

About the strainer itself: If there is anything left of the old one, no need for new. They are designed to be used, cleaned, repaired, and re-used. At worst, you can make one on the workbench using parts from the old one. Easy to repair even if ripped. They are typically a tubular screen tube made to slide over a light steel framework. The screen is usually a 200 mesh stainless screen although later ones were cheapened by using a nylon mesh material. The rubber end caps or light locating spring - if it even has them - don't have to fit perfectly. None of it is critical. The far end of the strainer fits into or over a feature - often a blind hole - cast inside the sump case, and the whole assembly is held in place by the strainer cover.

If necessary to repair, use 200 mesh Stanless Steel screen from the Ace Hardware to roll a new tubular slip-on cover using the old one as a support. Give it some overlap - maybe even 50% overlap- and sew or soft solder the overlapped edge. Or even just change the whole strainer assembly into an aftermarket outboard unit - which is what it should have been in the first place.
Good Luck,
rScotty

 

[richnfab]

Scotty,

Lots of great info and tips. Thanks!

I'll start with the easiest first and snug up the hyd line bolts on the pump and tank ends. I don't plan to break any of the metal to metal seals, but rather just clean and scuff them well and seal each connection from the outside only with blue permatex. The blue should also blend in well with the Satoh blue lines and frame.

This should eliminate any vacuum leaks. If that doesn't do it then draining the fluid and checking the screen is next.

Thanks again!
Ric

 

[richnfab]

Scotty,

So I drained the fluid this weekend. Nearly 8.5 gallons and it was nasty brown like molasses with a rusty tinge. Definitely not what it looked like on the paint stick test. Had a little bit of green goo snot toward the very end, but mostly looks like a lot of dirt, rust, and maybe wear, although I don't recall seeing metallic particles coming out as it neared empty.

The screen has some bb and pee sized holes in it and the o-ring on the outboard end was held in place with red permatex, and there was no gasket on the cover plate, only red permatex, so I will make a red rubber gasket for it tomorrow. The outboard o-ring is a little deformed so hopefully I can reuse it.

I ran it for about an hour prior to putting one side up on jacks, so all the fluid would drain to the access hatch. You can see in the pix just how dirty it is against a clean white bucket.

I was unable to find any 200 mesh SS screen at the closest ace or in town. I was wondering if I could go up in size to 120 mesh, or possibly even 20, to improve hydraulic flow and have greater strand strength?

I would think that flow would not be an issue across the screen, with the several wear holes thru it, but then again it may disrupt flow if it's not a uniform, hole free, screen?

Also, not sure of putting an inline filter on the suction line. I'm assuming you mean a cartridge style, non-reusable filter (oil filter style)? If that's the case aren't they meant to be pressure in and out, which in this case it would be just suction in? Would a cartridge/oil filter style filter collapse under vacuum? Assuming a paper element like an oil filter. I've never cut open a hydraulic spin on filter, but I'm assuming they don't use a paper element?

I also tightened up both ends of the suction lines and then cleaned and sealed them (see pix) with blue permatex. I got an additional full turn or more on each of the 3 rear suction line bolts at the hyd tank.

So I gotta order some SS screen online, make a gasket, fix the screen, and then fill it back up and hope it works? If so, then I gotta get the 3-point working next.

Lastly, the loader bucket was on the ground when I shut it off and began draining it, so will I need to bleed the air out of the hydraulics since the cylinders were unaffected?

Again, thanks for any help or advice!

Ric