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Kevin, Technician
Category: Agriculture and Farm Equipment
Satisfied Customers: 732
Experience:  Over ten years of expirence in Ag Electronics and Hydraulics
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My jd 6620 combine hyd oil is getting so hot it smokes and

Customer Question

my jd 6620 combine hyd oil is getting so hot it smokes and boils out the sight bubbles on the tank . The valve box under the seat for the unload auger and concave reel speed lever seem to be free not stuck. Could a bad filer in the tank be the cause ,please give me some clues to check. Thank you !
JA: What is the complete model and serial number of your machine?
Customer: Don't known without looking on the machine ,but it's an early 6620 Turbo I was told it was the first year production.
JA: Anything else you want the agriculture mechanic to know before I connect you?
Customer: no
Submitted: 8 months ago.
Category: Agriculture and Farm Equipment
Expert:  Kevin replied 8 months ago.

Hello, my name is ***** ***** I can help you with your question.

There are two common issues that cause the oil heating issue that you describe. The first and easiest to fix is to make sure the two hoses that would normally drive the reel are plugged together if you do not have a grain head installed. If you are running a corn head and the reel drive hoses are not plugged together then the reel drive pump is continuously running over relief pressure. This causes the oil to overheat rapidly.

Ok so the next most common cause is a little more in depth. There is an o-ring in the unload auger swing valve that is known to fail causing high pressure oil to leak back to the return path. Typicaly when the o-ring fails the hydraulics for feeder house raise to slow down. There is an elbow fitting that comes out of the back of the unload auger/cylinder speed control valve. If you unscrew the elbow fitting from the valve you will find that it has a tube attached that has an o-ring groove at the end. There should be an o-ring in the groove in the end that needs to have an o-ring on it.

Please let me know if I can be of further assistance.