Good afternoon gentlemen, Tractor reference is 1999 Hitachi 230lc-5 S/n ANT400040 this tractor as about 7000 hours on it. It has always been a good machine other than being rough (compared to newer). Well taken care of and used daily. I noticed today that the hydraulic oil is very dark, nearly black. It wasn’t like that last week when I checked it. The only difference between last week and now, is we have been burning trash. What could have caused the oil to turn so dark? I know that my upper cylinder leaks, would it be possible that ash has been sticking to the rod and the scrapper ring has failed allowing ash to get in the oil? That’s my only guesss of entry other than it being internal(pump). The hydraulics work fine and is still plenty strong. No noises or sounds.
Engine oil leak into hydraulic oil?
Chances are the hydraulic oil has never been changed and is starting to wax up.It is recommended that you change out the hydraulic oil every 2000 hrs and more often if you have any heat producing attachments like a hammer or a saw head. And check the leaking cylinder for dents on the chrome as that will contaminate the oil over time. It may seem expensive to buy oil but actually its one of the best things you can do to avoid future problems.
Thank you for the responses, The engine oil level is fine, it hasn’t moved up or down.
We changed the hydraulic oil last year.
I used to think that all oil came out of the same can but its all about the additives . The reason the oil goes black is that its oxidized (overheated). Synthetic oil ,although its stupid expensive ,will resist that oxidization and will pay for it self in the long run.If you google hydraulic oil there is enough information there to keep you reading for a long time. There may be an additive package that is recommended by the manufacturer that could solve your problem. For now I would recommend that you put a fire hose to your hydraulic oil cooler and make sure you are not developing any unwanted heat in your hydraulic system(bad circuit or main relief valve)
If that was the case wouldn’t the temperature gauge inside the cab show running hot? I completely agree that all oil is not the same. I just can’t wrap my head around why this would happen so randomly. We have used this machine to burn with before. Nothing out the normal has sounded, acted or smelled unusuall. there is a crack in the muffler. Which is located near the oil tank. Would that lead to cause this problem? But still I would think the temp gauge would raise.