Hydraulic pump basics

[rScotty]

That's interesting. I'll bet when you got those 2 to 4", worked the valves, heard the fluid move, and saw it hold in the new position you thought it was going to be easy... I know I would have.

First of all, I don't know. But here are three guesses:
1. One is that the cylinder shafts were really corroded and where they began to enter the cylinder body they are now jammed in that bushing and won't move. The problem with this, is that hydraulic cylinder shafts have a wiper, don't corrode easily, and you probably cleaned them up a bit when you saw it might move.
OR

2. Your jacking force should have caused some fluid back through the return line to the hydraulic sump when you worked the valve. And it must have done so, after all you heard something happen. And now for some reason the return line is not accepting fluid. I don't like this idea because the one part of a hydraulic system that is always working has to be the return. Otherwise big danger. So returns are over designed. But it is simple to figure out which line is the return, and loosen the fitting to see if fluid sprays out.
OR

3. Maybe your jacking force cause fluid under pressure to leave from the compression side of the hydraulic cylinder, and for some reason the valve didn't do it's other job - which is to allow some fluid to go into the side of the cylinder closest to the ram and now you have a vacuum lock there. That's why you can lift it a little and it returns to where it was.... and why you cannot get the valve to move any more fluid.

I like this last idea the best. So put some force on it, loosen the hose fitting on the ram side of the cylinder to let some air in, and see if working the valve makes fluid flow now.

READ!
BTW, I'm going to assume that when the engine runs, the hydraulic pump turns, and and you have checked somehow to see that you are actually sucking fluid into the hydraulic pump and returning it to the sump. If not, lets back up right now and you should immediately think about what I'm sayng next.

Most hydraulic problems are one of three or four things, and all of them end up starving the suction side of the hydraulic pump. One is too little fluid, another is a cleanable screen clogged, or a clogged hydraulic suction fllter, or most common of all is an air leak in the suction hose between sump and pump. that air leak can be tiny and impossible to find. Cure is to replace hose.

You know it is returning properly when you can undo the return line and put it into a bucket, start the motor, and then quickly stop before you pump all your expensive hydraulic fluid all over the ground.
Or make up a section of clear vinyl hose - there shouldn't be any pressure - or nearly none - in the return flow....only flow.
Luck,
rScotty

 

[oldnslo]

Are you the same person that posted questions about what two valves do on a 4500? If yes those diverters might direct oil to either loader or back hoe.

Does engine or pump change sound when attempting to operate either loader or the hoe?

 

[Quantumkev]

I will be honest with you, when the bucket started lifting, and I heard the fluid moving when I released the valve, and did that a couple of times, YES, I did think it was going to be easy…. I should have known better.

To your point one. The shafts are a little pitted/corroded, but nowhere near enough to cause them to jam. Layer into this when I jack the loader I see the rams moving, so I know they are not jammed, and when I release the jack I see them move back. So we can rule out number one completely.

Before I get into two and three let me explain where my head is at. Because some people may have been thinking, if the engine starts and runs, why not just use the hydraulics to move the loader/hoe. Here is the back story on that.

It starts up really easy, and idles real well.

When I dip the hydraulic tank I show EMPTY. But I know I am not completely empty, just empty enough to not show on the dipstick.

I started and ran the engine a few times, no issue no problem. Then after I had messed with it, jacking the loader, and also one of the stabilizer feet on the hoe, and had heard oil returning to the system, I started it again. It was at this point I started blowing what I would describe as “snow”. One of the fittings that connected the main pump pressure outlet to the main hydraulic line running to the hoe was loose… what came out literally looked like snow. (Ruining a pair of jeans, and maybe my favorite boots in the process….) what I mean by snow is that it was white, and fairly light (like a clump of bubbles). I know milky white is bad, but I am not sure yet if my hydraulic fluid is milky white, or if when I moved the cylinders and put a little bit of fluid back in the tank it is barely enough to supply the pump and it just aerated the oil like crazy, then when it blew out the loose fitting it had a Venturi effect and aerated a little more so just looked like snow.

Layer into this that when the tractor is off, I have no oil leaks. But as soon as I start the tractor I start to get a drip from the hoe. Can’t tell where it is coming from, but it is either the dipper or bucket hoses (they all disappear together into the boom so it’s hard to tell where the leak is coming from). Layer into that that I am not operating any of the valves, so one of them must be passing fluid.

So my logic was to try and get the loader back to my place, so I can work on it with all the convenience of having all of my tools to hand, rather than working on it 45 minutes away.

I am starting to think maybe my better path is to try and fix the hydraulics where it sits, even if only just enough to get it loaded and Mack to my place. If the hydraulic fluid really is milky and white I guess the damage is already done, so use what I have to get it back to my place. Maybe throw in a gallon or two just to get everything moving, then drain and flush when I get it back to mine without wasting $150 on hydraulic fluid just to get it back to mine.

Any thoughts on that?

 

[jigs_n_fixtures]

The ”snow” is whipped up hydraulic fluid, because you are really low.

I’d add just enough hydraulic fluid to get things moving. And, I’d put some of the UV die in the fluid, to highlight leaks. Then when you get it home, keep it just full enough to keep trouble shooting. Then when the system is tight again, drain and replace the fluid.

If you have a pressure washer, clean the suspect areas for leaks, then cycle the hydraulics one at a time, and scan with the UV light. if you don’t have a pressure washer you can clean things up pretty fast with brake cleaner, but it may cost a lot to get everything clean. You could try running past a self serve car wash, and hosing off the hydraulics, and the engine/transmission.

You can add the UV die to both the engine, and the transmission oils and then you can scan it for leaks and tighten/replace/repair as necessary to get it as tight as you want.

You can also use one of the 4-ton porta-power type hand pumps to pressure check hydraulic lines for leaks. get one with the pressure gauge, and pump it up and watch the gauge. If it won’t come up to pressure, or the pressure bleeds off, that line has a leak.

 

[rScotty]

I will be honest with you, when the bucket started lifting, and I heard the fluid moving when I released the valve, and did that a couple of times, YES, I did think it was going to be easy…. I should have known better.

To your point one. The shafts are a little pitted/corroded, but nowhere near enough to cause them to jam. Layer into this when I jack the loader I see the rams moving, so I know they are not jammed, and when I release the jack I see them move back. So we can rule out number one completely.

Before I get into two and three let me explain where my head is at. Because some people may have been thinking, if the engine starts and runs, why not just use the hydraulics to move the loader/hoe. Here is the back story on that.

It starts up really easy, and idles real well.

When I dip the hydraulic tank I show EMPTY. But I know I am not completely empty, just empty enough to not show on the dipstick.

I started and ran the engine a few times, no issue no problem. Then after I had messed with it, jacking the loader, and also one of the stabilizer feet on the hoe, and had heard oil returning to the system, I started it again. It was at this point I started blowing what I would describe as “snow”. One of the fittings that connected the main pump pressure outlet to the main hydraulic line running to the hoe was loose… what came out literally looked like snow. (Ruining a pair of jeans, and maybe my favorite boots in the process….) what I mean by snow is that it was white, and fairly light (like a clump of bubbles). I know milky white is bad, but I am not sure yet if my hydraulic fluid is milky white, or if when I moved the cylinders and put a little bit of fluid back in the tank it is barely enough to supply the pump and it just aerated the oil like crazy, then when it blew out the loose fitting it had a Venturi effect and aerated a little more so just looked like snow.

Layer into this that when the tractor is off, I have no oil leaks. But as soon as I start the tractor I start to get a drip from the hoe. Can’t tell where it is coming from, but it is either the dipper or bucket hoses (they all disappear together into the boom so it’s hard to tell where the leak is coming from). Layer into that that I am not operating any of the valves, so one of them must be passing fluid.

So my logic was to try and get the loader back to my place, so I can work on it with all the convenience of having all of my tools to hand, rather than working on it 45 minutes away.

I am starting to think maybe my better path is to try and fix the hydraulics where it sits, even if only just enough to get it loaded and Mack to my place. If the hydraulic fluid really is milky and white I guess the damage is already done, so use what I have to get it back to my place. Maybe throw in a gallon or two just to get everything moving, then drain and flush when I get it back to mine without wasting $150 on hydraulic fluid just to get it back to mine.

Any thoughts on that?

I think you are on the right track. Lets talk about hydraulic fluid for a moment. The problem with hydraulic fluid is that there is no governing body.... no universally accepted requirements or even preferred chemistry. All the societal and governmental constraints like SAE and Oil Institute Standards you have in lubricating oils and even for fuels do not exist for hydraulic fluids. So they can be anything from alcohols to keytones to glycerins.... or mineral or vegetable. Some eat up seals. Some turn solid, and most are either miscible or react with water. Some wll burn, some put out fires.

Mixing with water is classic hydraulic fluid misbehavior. So that is what is probably causing your snow.... a weird hydraulic fluid mix plus some water - combined with who knows what and then a fascinating change of state caused by the pressure change from pumping. The "snow" may not ruin your boots but the "hydraulic fluid" component might. Snow!! Neat!!

Find some of the lightest viscosity and least expensive MOTOR OIL or Hydraulic Oil you can get. Either will work fine for short term to get home and troubleshoot. Drain as much of what you have out, and add enough new fluid to get it circulating and TO PROTECT THE PUMP VANES!!
I'd like that reservoir half full or better when the cylinders are full. It might even work then.
Cheap is fine. SAE 10 weight is plenty viscous. 0W-10 motor oil would be even better. The pump is very sensitive to suction cavitation pitting the metal inside the pump. Terminal for the pump..... But pumps are replaceable. Still, lets get what you can out of that one.

I've got a feeling this is going to be one of those that works out well. Hydraulics on those old tractors are easy to deal with. You've got engine and tranny - that's most of the problems solved right there.

rscotty

 

[rScotty]

Are you the same person that posted questions about what two valves do on a 4500? If yes those diverters might direct oil to either loader or back hoe.

Does engine or pump change sound when attempting to operate either loader or the hoe?

Right. It could certainly have a manual diverter valve so that the operator could choose either the loader or the backhoe - but not each at the same time. Massey used a similar thing.

So it is worth looking at to see if that is his problem. Number 4 on the list of probabilities. Good catch.

The manual diverter doesn't put the systems in parallel, they are considered as two independent series hydraulic circuits as you and I have been saying all along.

Now I admit that sometimes there will be a proportional power steerig valve in the circuit prior to the manual diverter and that Power steerimg proportional valve does steal a little flow for the power steering. Spoiler alert: That PSPV really is the definition of a parallel flow system....but suggest we ignore it for now because it is small quantity.... unless nothing else works. Hmmmm..... except it could be the Power Steering proportional valve if the fluid level is low. Normally the PS has priority on any fluid for safety reasons.

Still, his best bet is to get that old fluid out and half full or better of some kind of fluid so that he can do some decent diagnostics. Then probably either you or I or several other TBNers could get him going.

rScotty

 

[LD1]

Id start by getting the hydraulic oil to proper level

 

[pmsmechanic]

Id start by getting the hydraulic oil to proper level

First drain out as much of the old "oil" as possible. My guess is that it's mostly water by now.

 

[davedj1]

Undo the hoses for the crowd boom and jack it up then chain it up , should hold till you get it home.
Same for the outriggers if they are down.
It will also work for the bucket.

 

[LD1]

First drain out as much of the old "oil" as possible. My guess is that it's mostly water by now.

Certainly worth a shot.

Just don't have enough info....like when the last time it ran? But from the sounds of it, it ain't got anything in it other than the dab purged out of the cylinders by manually jacking the loader