Too much hyd fluid?

[Crisswell]

In every case I know of, the oil resevoir is simply that. There is no "pressure" in the "sump", be it a tranny or rear end. The hydraulic system picks up oil from that sump, then the pump puts it under pressure with-in the confines of the internal system. Transmissions and rear ends SHOULD be vented to prevent any accumulation of pressure (from heating of the oil?) to prevent seal damage.

Thanks!! Now it makes sense!! That's the piece I was missing.

Andy

 

[Soundguy]

>My question is doesn't more fluid (over full) = more internal system >pressure? The only experience I have is with oil in an engine. If you want to >blow the seals, keep you oil over the full line for a period of time.

As it has ben discussed here, many times, the hyd sump on most tractors are not a pressurized sump... It's a holding tank ... the pump sucks fluid from it, and fluid is also exhausted into the tank from returns and reliefs.

Many systems are designed to hold extra oil capacity so that you can run aux hyds. ( check your manual.. it may state how much you can overfill your sump, or how low you can safely go .. my ford.NH manuals do. )

>But the part that's confusing me is, does that mean you may have to drain >the tractor system back to some safe level above max when you unhook >the implement when you're done

See above.

>I'm assuming that not all attachments are created equal when it comes to >hyd fluid requirements - some need more, some need less. So how do you >know from the dipstick how much is too much at the end of the day and >you've unhooked? Or have the mfg's build the hyd fluid resovoirs so much >bigger than the tractor carries at "full", that you don't have to worry about >it?

Again.. see above.

>I'm also assuming that most of the fluid from an attachment drains back into >the tractor resovoir before you unhook

Depends. I fthe implement has SA cyls that are compressed when you hitch up, and then you extend them for use, and then they compress again before you unhitch, then yes.. mos t of the hyd oil makes it back to your sump.. minus ov course, any air voids int he lines that your oil made up for, as that will most likely stay int he implement lines when you unhitc.. thus you only loose the volume o fthe oil in the lines.. if any.

Very similar with a DA system. The fluid is ballanced on a da system.. in/out are virtually equal.. and the only loss you would experience is if the lines and cyl were dry when you hitched up... then you could loos eup to the volume of the cyl, and the lines... etc.

Your hyd dipstick may have a crosshatch area showing you a range of running.. or your untis manual may say that it is ok to use a hyd implement with X volume without adding extra oil.. or that you can add X extra qts of oil to make up for hyd losses due to aux implements.. etc

Soundguy

 

[IslandTractor]

I just searched and found this thread after inadvertently adding ??three quarts more hydraulic fluid than I needed to after replacing some lost from a leaking fitting. The thread is reassuring but does not address one thing that I noticed at the end of the day.

I used the tractor all day with the excess hyd fluid and noticed no problems. The tractor worked hard raking and filling in stump holes as well as moving a large pile of logs and brush. The engine was almost always under load as I was raking while moving the brush pile for about six hours. I had apparently misread the dipstick in the morning after adding fluid as I thought it was normal. When I checked it at the end of the day I noted immediately that I could see the fluid in the dipstick (not normal) and that it was bubbly, almost creamy in appearance. Fifteen minutes later the bubbles were gone.

Should I bother removing some of the fluid?

 

[john_bud]

I just searched and found this thread after inadvertently adding ??three quarts more hydraulic fluid than I needed to after replacing some lost from a leaking fitting. The thread is reassuring but does not address one thing that I noticed at the end of the day.

I used the tractor all day with the excess hyd fluid and noticed no problems. The tractor worked hard raking and filling in stump holes as well as moving a large pile of logs and brush. The engine was almost always under load as I was raking while moving the brush pile for about six hours. I had apparently misread the dipstick in the morning after adding fluid as I thought it was normal. When I checked it at the end of the day I noted immediately that I could see the fluid in the dipstick (not normal) and that it was bubbly, almost creamy in appearance. Fifteen minutes later the bubbles were gone.

Should I bother removing some of the fluid?

YES! get the extra out ASAP> in your case you list the one bad thing that you don't want to see. Bubbles. They don't lubricate. They also collapse and that is known as cavitation, which is an odd phenomenon. But a powerful one, cavitation can actually eat thru metal. Well known in high flow diesel cooling systems that cavitation can cause holes in the cylinders and then they leak.

I doubt that there is any damage from 6 hours of use, but over time, it will cause problems.

 

[IslandTractor]

That is what I was wondering. Soundguy indicated there was no big deal to more fluid but it sounds like his tractor sump just is huge. I overfilled by only 2-3 quarts max (probably 2) but clearly saw the cloudy fluid that cleared.

What would cause the bubbles/cavitation? I was initially worried about just that then saw this thread which seemed to dismiss the concern. Is my HST that different in how the sump is set up from what Soundguy was discussing? This is a Kioti CK20 HST.

 

[john_bud]

Is it that different? Yes. I can't speak for Soundguy, but in general older tractors have one location for the sump and then the pump located on the engine. HST tractors have the HST pump, rotating shafts, other moving parts in the case which is the sump.

Why the bubbles? Don't know exactly, but in general the sump fluid level is low enough that any moving parts don't splash around in the liquid. Overfilling that causes bubbles, means that some moving part is splashing around in the fluid.

Given that a 2-3 qt overage causes bubbles, you may want to fill it so that when all the cylinders are fully extended the level is exactly at the low fluid level. Then check with all the cyliders fully retracted and see if it is above the high level. And if so, if it causes bubbles. My guess is that it won't be over full that way (and if it is a little over it won't cause bubbles), but you need to check it out to be sure.

jb

 

[Soundguy]

It's not only an older tractor issue.. it depends on how your tractor was built. My 'new' Nh 7610s has a huge sump.. nearly 50 qts.. and you can add another 13 to it. The main pump for that tractor is behind the tranny..( not sure if it is seperated from the common sump and has fluid piped to it.. or if it is imersed... in any case.. it is not engine mounted.. Again.. it is all in design. That's why i said to 'REFER" to the owners manual to see what they say about overfilling sumps.

Foaming of oil was also covered in the previous posts. Obviously his make of tractor is one that doens't like overfull sumps, and thus foaming is a problem for the specific reason you state. What we need to see/hear is what his owners manual says on the issue. It's likely there is a charge pump before his HST pump.. so there is alot of stuff going on in that sump.

Again.. pretty much all my posts on this subject state clearly to 'check the owners manual' to see what it says about overfilling. My manuals for some of my tractors state if, and how much you can safely overfill them... that's why i keep saying.. RTFM!!!!

Soundguy

 

[Soundguy]

HST's are their own beasts from the engine flywheel back to the diffy ring gear, they have a much different design than a standard trannied tractor.

That's why i said RTFM...

Soundguy

That is what I was wondering. Soundguy indicated there was no big deal to more fluid but it sounds like his tractor sump just is huge. I overfilled by only 2-3 quarts max (probably 2) but clearly saw the cloudy fluid that cleared.

What would cause the bubbles/cavitation? I was initially worried about just that then saw this thread which seemed to dismiss the concern. Is my HST that different in how the sump is set up from what Soundguy was discussing? This is a Kioti CK20 HST.

 

[IslandTractor]

Thanks guys. I'll remove a quart or two before using the tractor again. I still need to find a Caterpillar dealer or some place that sells dye for UDT!

Actually in this instance the dye was not the issue as I was in fact checking carefully by touching the dipstick to a clean rag as I filled the hydraulic fluid. The tractor was off and I did not check again after starting. Not sure how that would be a problem but that is all I can figure out. Loader was up as was 3PT while filling/checking.