Heater in 1987 Excella making a loud whine, just started

[Airstruck]

Our wonderful warm air from the furnace in 1987 Excella just started screaming (whining) in the middle of the night. Any clues on where to
start looking to repair? A bearing maybe?

[overlander63]

Other than giving it some cheese to go with the whine, you're looking at a new motor. Almost every time the bearings start squealing, the motor will need replacement. You can lube the bearings, and shut them up for a while, but 90% of the time it will just come back.

[Jammer]

Terry is right. 20 years is really all the longer these will last so you're already on borrowed time. While it is possible to relube the bearings, it requires disassembly and is not usually a lasting repair. If the heat exchanger is in poor condition, this might be a good time to replace the entire furnace.

[Lumatic]

While Overlander and Jammer are correct, if you can stand the squeal for a while it may quiet down after a while especially if it has been sitting for a while. A good kick also might provide the needed attitude adjustment. Won't hurt anything except ears and foot. Just like me.

[mimiandrews]

Our furnace will make an awful screaming noise if the fuel/air mixture is wrong. Suburban service manual mentions this as a possibility, and adjusting the air shutter fixed it. Someone posted a link to the manual a month or so ago, I've forgotten just which thread. Search might find it.

If it's really a bearing, I agree with the above.