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TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel

1 recommendation

Furnace blower bearing totally FUBAR

Click for full size
Click for full size
Anyone seen anything this bad before? It's surprising that it continued to work as long as it did, without the slightest abnormal sound. Yes, that bearing is indeed worn to an oval shape. I can poke a paperclip between the shaft and the bearing!!!

This is at a place I'm renting. A call to the landlord has already been made. For now, I've made it quiet again by cleaning out all the metal shavings, rotating the bearing 180 (so the forces on the bearing are on the less-worn portion) and oiling the hell out of it.

Furnace manufacture date is 1976. Wonder if he's going to replace it, or spend the money to repair the blower assembly, which will need a new shaft and two new bearings.

By the looks of things, my assumption is that these are the original "permanently lubricated" (sealed, there is no oil hole) bearings.

Tip: don't wait until you hear noises before you decide it's time to apply some oil, as it's probably already too late. Of course, this applies only if your furnace has oil holes on the bearings. However, even sealed bearings may be re-lubricated by carefully drilling a small hole in the side of the bearing housing.

Anyways, this post is mostly just for your enjoyment and information. I'm not seeking help or advice.


leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:10
Reviews:
·SONIC.NET

said by TheMG:

Furnace manufacture date is 1976.

About the same age as mine. Bearings are sealed as well.
You said it didn't make any abnormal sounds, how did you find out anything was wrong ?
I don't really want to take it apart while it is working well.
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jrs8084
Premium
join:2002-03-02
Statesville, NC
kudos:1
Reviews:
·AT&T U-Verse
reply to TheMG

Just curious: was this a belt drive setup and was the point of wear in the direction of belt tension? (i.e. was the belt minimizing shaft play/noise?) You wouldn't think so, but bearings can do weird things when they wear out.

The 1971 blower assembly on my furnace does have oil ports I put a SMALL drop or two in there every now and then.


TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
reply to leibold

said by leibold:

said by TheMG:

Furnace manufacture date is 1976.

You said it didn't make any abnormal sounds, how did you find out anything was wrong ?

It did start making noise just today, that's when I looked at it and found what you see in the pictures.

Looking at the amount of wear, the bearing was obviously out of oil and on its way out long before it started making noise.

said by jrs8084:

Just curious: was this a belt drive setup and was the point of wear in the direction of belt tension? (i.e. was the belt minimizing shaft play/noise?) You wouldn't think so, but bearings can do weird things when they wear out.

Indeed, this is a belt drive setup. The wear is in the direction of the belt tension.