On 26 Jan 2004 20:37:37 -0800, wrote:



I have a Lennox 80MGF furnace that is making loud noises from time to
time. I first thought that the blower's ball bearings or something was bad
and that the motor action is what was producing the loud noises.

The noise happens only sometimes and is rather loud.

You didn't describe what the noise sounds like. If it squeaks as from
a rotation then the only moving parts are the fan axle (most likely)
or the motor axle (unlikely). The motor axle runs on dry bronze
bearings and the bearings are quite easy to replace. Just go to a
furnace or an applicance parts place and ask for them. There is only
one standard axle/bearing diameter size.

Don't put any lubricant on the bearings. The heat just dries up the
oil or grease so that along the way the worn metal filings forms an
abrasive slurry with the lubricant and eats up the bearing. I believe
when the bearings run dry the metal parts polish each other to give a
low friction mirror surface.