Combines 750 Automatic header control

JJS

Guest
First is your selector in the right position.Most of these combines had a selector down by the axle.This had two different orafices inside. This controlls the drop rate, one for corn head, and one for grain head. Then you need to check your Header Assist Springs. They are suppose to be adjusted so that there is a specific amount of pressure at the lift Cylnders. when the head lifts. I can't remeber just what it was. You will need a book to find out, or somebody else might know. If these are ok, then your pump might be getting week. HTH Joe
 

cookie_jar

Guest
I had a similar experience last year with my 750 header height control. When I hooked up the pressure gauge to set the pressure, it was oscillating wildly, and couldn't be set to factory specs. I noticed that the plunger on the hydraulic valve controlled by the header height cable was bouncing, and was leaking fuild. I ended up replacing the tapered plunger 1 042 194 M1 called a pin in the parts book, and the O ring 365 398 X1. I also got a seat for the valve 1 042 193 M1, but couldn't figure out how to remove the old one. In any case, changing the "pin" and O ring did the trick for me, and the height control was back to normal. Hope this may be of some help. Good luck.
 

JJS

Guest
Sorry I can't remember how it was done on mine.Some of the slip clutches on the MFs had spacers inside the spring. You would tighten down tight ot the spacers, then back off so much of a turn. It is also a possibility that the springs have gone bad. It is not unusual that after setting compressed for a long time that they take a set, and no longer have enough strength. I would start at a certain point, and just keep tightening a little until it nolonger slips. and as long as they aren't bottomed out, you should be ok. Good luck Joe