jonbates5
Member
I have a 320bl that keeps blowing up swing motors and we are on number 5 at this time. I have just got involved on the last motor so I can only go from there. We had the motor completely rebuilt with all new parts. I had a Cat mechanic test the drive motors and the swivel and there were no issues with either. We did find the pilot pressure was set to 400lbs and we reset it to 650. In testing the case drain we found it elevating at times to 150lbs when reaching out with the dipper and main boom and uncurling the bucket all at the same time. Individually it stayed in the area of 50psi. We separated the case drain and ran it to the bottom of the tank to keep it under pressure and always wet to prevent cavitation of the cushion valves and everything worked for about 50 hours then she failed again. When she failed the first thing was she just didn't stop in swing, just continued to drift after the stick was returned to center. Then shortly after a few times of that she started making a metal on metal grinding sound. then she stated locking up in swing, then complete lockup. this all took place over 15 minutes of getting her for the work area to parking. Not sure whats causing the slippers to fall off and I'm at a point of either fixing or taking her to the auction or scrapping her. I really don't want to auction this nightmare to anyone.