Came close to losing 7720.

Parked 7720 for the night. Came out the next morning and
found this. Could have been a disaster. What would have
caused this hot spot?

Feeder beater bearing or feeder house chain bearing got hot and smoldered on the crop residue.....you are very lucky. A good habit is to walk around the combine and feel each bearing for hot spots when you shut it down for the day.....esp. if you park it indoors.

Ben

Leaf blower used on the machine each evening will help prevent fires...plus as you walk around blowing it off you may spot trouble.

As Ben stated below you have a bearing on its way out. It takes time but a good gas powered leaf blower will clean your machine off nice each day.By buying a thermal heat gun you can read bearing Temps with machine running and also at the end of the day.Looking at the picture you are very lucky you still have a combine.I never thought much of the thermal heat guns until I seen our maintenance people tell which bearings were about to fail on our equipment at work before you could feel them hot to touch by hand.

That could be spontaneous combustion too. That looks like it's been wet, then adds one dry dust on top and it could happen.

Ya lucked out on that . I had my Massey 300 have a bearing go out on the cylinder variable drive while opening up a corn field , i had the ends done and was splitting the field when the speed control handle started to spin in the cab and smacked me in the arm and as i turned to look at th spinning crank i saw SMOKE coming off the right side . I needed to get it out of the corn fast and ran over about fifty feet of it making the exit out into a hay field . I grabbed my10# extinguisher and tried to get the small fire out and 10 #'s was not enough . Luckily i was about 300 feet from a house that had a garden hose hanging off the side of the house i drove the combine down close to the house and started putting water on it . Someone driving by on the hyway call the local fire dept that was a mile away and i was still spraying water on it when they showed up . I had it pretty much out when they got there . Other then some blackend paint two toasted belts a trashed out bearing i was vary lucky and vary thankful the gas tank was on the other side . Sure made a believer out of me that not only do you need a COUPLE extinguishers one should have a good source of a couple hundred gallon of water and a way to pump said supply of water near the combine .

That is long way from any bearing. Though I suppose it could still happen. I would suspect more like an ember from a leaf fire in the yard or off a wood fire/furnace doing that. Auger fingers are a plastic around the crank for the fingers and bearings are at each end some feet away. Feeder chain drum floats inside the feeder house so no contact there except the drum. Cross shaft is in the bottom of the feeder house so long ways away from the top of there. one end is in the reverser other is just a ball bearing on right side. So back to my original theory or somebody set it and failed at burning it.