JD 6620 - auto header problems - NEW DISCOVERY

First, thanks for the ideas you have given on this issue. Ok,start the combine and increase engine RPM to near wide open. Drop the JD 220 platform with the hand control and about 18" off of the ground the Dial-a-matic takes over and continues to lower the head. Head is 3 wire toggle switch(s) system and combine is DAM. Header and combine connected with John Deere adapter. Everything seems to work. As you move across the barnyard the header raises and lowers and you can hear the clicking of the solenoids.

Well, I walked around to the right side of the platform with the engine still at high rpm and the Dial-a-matic still on the second spot. Reach in and pull on the "red ball rod" and the header raises, release and the header drops. It will do this up and down manually pulling and releasing the rod maybe 10 times over maybe 2 to 3 minutes just as it should. After a couple minutes it is getting slower and slower to lift the head and eventually it WILL NOT LIFT THE HEAD!!!!!!! All of this in 2 - 3 minutes. The auger swing still works just fine and the manual lever in the cab can still easily lift the head. All other hydraulic operations are OK as well. Shut it off for an hour and the header auto height control works just fine again for 2 - 3 minutes and eventually develops the exact same problem.

Now were do I go????? Sounds like as the oil warms it is bypassing somewhere easier then eventually bypasses entirely verse the weight of the head. The manual cab lever still easily raises the head even after Dial-a-matic has quit. Surely not the raising solenoid getting too hot. Hydraulic temperature light would come on last fall and eventually go off if you stopped combining for a while. It would stay off for sometime.

Appears to be a hydraulic issue. What are your ideas. Thanks Andy

I think you have a high pressure internal leak in the hydraulic circuit.

Get an infrared thermometer. Run the combine and check the various valves looking for one getting warmer faster than the others. Usually a high pressure leak will create heat.

Since the manual lever still works check the automatic circuit out first. You can have a solenoid valve leaking. Maybe even a bad coil too but it is more than likely a hydraulic problem not electrical.

When you say internal leak you probably mean some poppets or "O" rings are not sealing and letting oil by. The chances of a crack would be limited I would think. What is the hydraulic valve casting that has no levers attached to it and is located under the edge of the left hand side of the combine near the cab ladder. It is slightly forward of the auto header solenoid. Has some hoses and pipes coming to it. It would be above the left drive tire. That valve can get pretty hot by touch. Since this is a sidehill combine with big tires you can walk right under the combine and see this valve. I have do have a pointing temperature gauge that I will try today.

I remember changing a poppet in the valve you are talking about but do not remember the problem that caused me to open the valve up. I do remember the plastic was cracked on the poppet and that fixed the trouble. Sorry I cant be more help,sure sucks when cant rum the DAM. I have cut a lot of beans with a 7720 by watching the ball and manually raising and lowering.