Combines 7720 Combine rumble

Might be your hydraulic pump spud, our 6620 made a similar noise this winter and after draining the hyd resivor, changing the filter and putting in new oil it was gone. Is it cold where you are at, this also made the noise louder when the oil was cold. Also, just check the hyd oil level to see if it's low. What year is your 7720, hours, how much did you buy it forIJ let me know if you hacve any IJ's 95man

I would loosen your ground drive belts and check the engine power shaft bearing, sounds possible, hope this helps.

Separator running or notIJ

It sure sounds like the engine powershaft bearing to me. A friend of mine had a 6600, that the engine powershaft bearing went out on, and that is exactly what it sounded like.

This is with the seperator disengaged

If you are replacing the engine power shaft bearing, be aware that it can be installed backwards. The 7720 Combine Service Manual willl tell you which is the proper way to install it.

Your problem is the lifting eye bolted to the power shaft housing. The cover plate is being pushed down against this eye and hence a rumble. Remove the eye and try it. David

Rumble you describe turned out to be countershaft(big shaft under seat_engine, coming from lH power to RH, driving variable) pillowblock bearing on RH side of our 7720II w_3000hrs.