I watched a video on line intended to internally test hydraulic cylinders by plugging off the main hydraulic line on the back of the cylinder (main pressure face) and plugging the hydraulic line which serves it. Then with the machine running, the return control is actuated. If the cylinder extends under return pressure, then it indicates the internal seals are leaking excessively. Is this procedure valid for use on the 490E? I continue to have hydraulic overheating with this machine. About three years ago, I had all cylinders overhauled by the local CAT dealer's hydraulic shop. I know they did not use Deere factory seals, but rather substitutes. When I tested both the arm and bucket cylinders with this test they failed miserably. I have ordered the Deere factory seal kits for these two cylinders. Could hydraulic cylinder internal blow by be adding to my hydraulic heat problem? Thank you in advance for your thoughts in this regard.
Yes internal leakage will make heat just like running Hyd. over relief. I had a customer that his hyd. kept over heating and it turned out that he has a aux. valve that the pedal was stuck and that caused his over heating. If you have a heat gun you can normally shoot the cyls, and see witch one is hotter and tell that way that it is over heating. Be sure to check the inside of the barrel for any scoring
Dave; Thank you for your reply! Is the internal test described for hydraulic cylinders conclusive of bad internal seals? What temperature on the hydraulic cylinder would you consider to be excessive?
could be bad seals could be damaged cyl. bore or even a loose piston. just see what is running hotter than the others. do a temp test at the top and bottom of the cooler too to see if the cooler is removing the heat should be 20-30 percent difference if not check cooler bipass valve to see if it is stuck open or has trash in it
Good day This may be of interestKind regards Uffex