New to this forum joining awhile ago but have not posted until now. My problem is i bought a well used cat 320L last year for a farm machine maybe 250 to 400hrs a year is all i use it. Works well but twice now my right track will get stuck in reverse. Found out it was a main spool valve in the valve bank getting stuck in the down position, you can go and pry the spool up and will work abit or get stuck right away. Looking into it further i found metal fillings on the bottom of the valve. Thinking it was a bad track motor i changed track motor, oil, and filters put it back together and worked for about 200hrs until now same problem. My Question is If my system was contaminated with metal would i have not seen problems in other valves. Why would the valve never be stuck in the up positon Could the spool itself be damaged and need replaced or is it the valve bank Having a steep learning curve with excavators and hydraulics here Thanks for any help
Ok I will take the first shot at this. Not very familiar with the hyd on the 320 but these are my first thoughts. First off, I hope you still have your old filters as they tell the story of your system. You need to figure out which is the case drain filter and cut it open to inspect for metal. If a travel motor failed bad enough to send metal back down the return line, the case drain will have metal. Did you open the "failed" motor to confirm this was the failure ? Next is the 20 ft. of hose and swivel going back to the valve. If the valve has metal from the motor so will these. Did you clean or at least blow out the travel hoses ? Now for your questions- 1.If it continues and there is metal in the valve there is chance you could start to have other strange problems appearing in the future. Not enough may have drifted through the valve yet but I bet there will be some metal floating in there. 2.Not sure why it only sticks one way but if the valve "sticks" guarantee the valve is probably scored and housing (softer than the valve) is also scored. What I'm saying is if it gets bad enough the spool can stick the other way too 3. Yes you need to remove and check over the spool and housing. Try cleaning up/polishing the spool and check the housing. Most will say the housing is a machined surface and you can't clean it up because it opens up clearance between the spool and housing (for oil leakage) but a light clean up wont be the end of the world, just not ideal. Ensure the spool moves free in the housing when reassembling. Doesn't sound like the problem was fixed or else the system wasn't cleaned out properly. Good luck - remember nothing time and money cann't fix ! Keep updating on what you find