Has hydraulic fluid ever been *THE* problem?

Has anyone ever run into a situation where simply changing the hydraulic fluid fixed a hydraulic problem?

I can't see how it would be possible that the fluid would be so bad that it won't flow, but doesn't ruin the pump in the process.

As long as it's liquid and slippery, pretty much anything can be hydraulic fluid. Even water would work if not for the lack of lubrication. Water held in suspension by modern hydraulic fluid works nearly as well as pure new hydraulic fluid. At least, there isn't enough difference in how they perform for you to notice.

That is a deep subject but basically debris and water are what kill the oil and it can usually be reconditioned. Water WILL damage stuff. Localized heating to over 212*F will cause cavitation of the water in some cases (depends on pressures).

there is also an additive package in oils that adds lubricity and rubber protection. Bad fluid can ruin seals and cause leaks everywhere.

The by product of over heated multi viscosity modifiers is sludge but usually it will just break down as hydro oil and become nothing but the base oil. So if you use 15-40, you will end up with straight 15W oil.

HOWEVER - lab testing is become more and more the standard as we run low on oils. A lab can check for additives, contaminates, and recommend ways to refurb the oil good as new. All big mining companies are doing this today.

Try that water theory at 15 degrees.

(quoted from post at 11:19:31 08/29/13) Has anyone ever run into a situation where simply changing the hydraulic fluid fixed a hydraulic problem?

I can't see how it would be possible that the fluid would be so bad that it won't flow, but doesn't ruin the pump in the process.

As long as it's liquid and slippery, pretty much anything can be hydraulic fluid. Even water would work if not for the lack of lubrication. Water held in suspension by modern hydraulic fluid works nearly as well as pure new hydraulic fluid. At least, there isn't enough difference in how they perform for you to notice.

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I have seen that be the case at several of the USS mills back in the late 90's.

Fluid contaminated to the point of clogging filters and or plugging screens is usually what leads to changing fluid completely.Hydraulic oil ain't cheap but filters are out of sight, at least for everything I own.

Yep. Had an old Allis B with a belly mower working on it for someone. After mowing for a long time the mower would not lift. Pulled the pump and reseated the check valves thought that would do it as they were not the best. Oil looked clean and fine. Ended up changing the oil and then it was fine. Must of been breaking down in the heat or of the wrong weight ?

"Water held in suspension by modern hydraulic fluid" is one good reason to change hydraulic fluid periodically. I change mine right by the book. So many things can contaminate hydraulic fluid. I rarely see a farm tractor with dust caps on the scv outlets much less on the machine it's getting hooked to. Most farm tractors utilize the transmission and differential oil for the hydraulic system. Another source of contaminants. Each time the tractor gets hooked hydraulically to a 20 year old piece of machinery it's most likely getting a good dose of contaminants. "Exchanging of body fluids" I believe is what it's called.

A local company decided they would quit changing oil in there trucks when synthetic motor oil came out. They sealed the drain plugs. Engines soon failed. They analyzed the oil because the oil co claimed synthetic oil wouldn't wear out. It didn't but was about 50% gasoline.

My Ford 640 would lose all lift power in hot weather.The hydraulic fluid was a bit milky when I bought the tractor.Ford dealer said 134 would work fine it dosent.I dumped the 134 from the hydralic system and put in the 90w oil the service manual recommended and the trouble stopped.I can lift hardwood logs onto the sawmill in warm weather now.With the 134 I could not lift the 350 pound cordwood saw in warm weather.The experts will tell you that that the vane pump is NG and you have to spend 1500 bucks plus to convert to a piston pump.I spent 15 bucks to put some 90 w mineral oil in the system and it works fine.Its a little stiff in winter but a few quarts of 80w will fix that.Ford said add 2 quarts of 80w if you use the tractor in winter.My Ford service manual says 90 w all the way to the 1000 series.Many of these fools repeat wrong info on forums.They have no practical experience with hydraulics, Just pass on wrong information.I started working on tractor hydraulics in the mid 50s

On our '05 Honda Rancher 4-wheeler (automatic transmission with either auto or manual shift function), the owner's manual says to change the engine/transmission oil every 600 miles. Whenever we get near that mileage, the transmission will slip a little going up hills. After we change the oil, everything is fine for another 500-700 miles. So I believe that just changing the oil will change how well something operates. And we have found that nothing but CJ-4 oil will work with this machine....

Ask yourself the same about motor oil and filter in an engine. Ever seen an engine where the oil is so dirty and thick that it clogs the filter and passages? Many an engine has needed to be rebuilt due to the damage caused by that. The same goes for low level of oil, especially if the engine is using hydraulic lifters. If they can't pump up do to dirt or low level, well...

As I pointed out a day ago about someone's Deere 950 that won't raise an implement more than 8" off of the ground. It shares tha same hydraulic fluid as its manual transmission and everything else like the remotes and loader. The spin on filter is positioned under one of its floorboards, and like any other filter, filters dirt and other impurities. If it wasn't important, it wouldn't have one is my guess. But it does have one for a reason. By the same token, if the hydraulic oil is low in the transmission, its also low to the pickup that would send it throughout the system if it had enough to do so. Hydraulic cylinders don't get pumped up to hydraulic if there's nothing to hydraulic them with, whether it be from dirt or low level or contamination.

Mark

I have. I have an 830 Case that I use a batwing finish mower on. I used cheap hydraulic fluid in it and when it was hot it would not lift the wings. I changed the filter and cleaned the suction screen which had a lot of plastic shavings stuck to it. I put in new cheap oil and the problem returned. If I would get the wings up a little I could shut the tractor off and let the wings down the oil returning would flush the screen. I changed filters and cleaned the screen and put in the oil it was supposed to have and no more plastic shavings or plugged screens. I think that cheap oil had ground plastic in it to keep the gears quiet.

I kind a liken it to the old addage that if your automatic trans is acting up just change the fluid/filter and it will take care of it. 99% of the time it is allready too late and the same with most of the power shift and/or any shared lubricant type tractors. You may correct one or two of the malfunctions but usually the dammage is done. A lot of used car deallers will change an ailing auto trans car fluid and add some conditioner to swell up the seals a little just to get it sold and off the 30 day warr before it settles in to failure again.