How to lubricate fan bearings in furnace?

[maillemaker]

So in our 27-year-old Winnebago Warrior, we have a Suburban NT30KLT furnace.

In the last couple of years, the first time it fires up you can hear the fan bearing squalling a bit and then it quiets down. I'm sure it needs some oil. Presumably they use oil-impregnated bronze bushings in the motor assembly and I'm sure they have just dried out over the years.

I pulled the access hatch, but all you can see is the burner chambers. The squirrel cage fan is behind the heater box, and there is no access to it.

It appears the outside exhaust and intake frames screw into the side of the camper and hold the tubes tight on the furnace on the back end. I can't see anything that secures it from the front. Does it just pull out? Looks like I'd have to disconnect the gas line and the ductwork which is not going to be easy.

Any ideas?

Steve

[maillemaker]

For future readers, the motor is here:

https://www.makariosrv.com/suburban-furnace-motor-521137/

If I could get the fans off the shafts, I'd replace the motor.

Steve

[maillemaker]

There was some rust on the burner assemblies, but not anything in the motor housing that I could see.

I ended up squirting light oil (RemOil) onto the end of the shaft. Since the shaft had a flat spot ground on it for the set screw, the oil could go down the flat spot, through the fan cage, and, hopefully, down to the bearing. I did this for both ends of the motor (both fans).

Put it all back together, and there is no squeal on running now. I don't know how much oil I was able to deliver to the bearing, so I don't know how long the fix will last.

I should have tried setting a socket on the fan cage hub and giving it some light taps after letting the oil soak in.

Steve

[trailrider]

Not pressed on. Rust!

[maillemaker]

I got the furnace out this weekend. I have the blower assembly disconnected from the rest of the furnace, but I cannot remove the cage fans from the motor shafts. I was able to break loose the set screw on the smaller fan, but not on the larger fan. And even when the set screw was loosened, the fan would not come off the shaft. Is it pressed on?

Steve

[Chum_lee]

I like Tri-Flow bike chain lubricant. It comes in an aerosol can with a fine straw spray nozzle. It works great for Kwikee steps too.

Chum lee

[maillemaker]

Couple of post prior I gave you a clicky to the zoom spout oiler. What you can't tell is that the thing pulls out about 12 inches and can get into just about any tight space.

The problem is that I cannot see the fan. When I pulled the metal covers off of the intake and exhaust I could barely make out the cage of the fan, but can't get any access to the fan motor bearings.

BTW, don't get snippy with posters. If you knew everything you wouldn't be asking these dumb questions.

I just get annoyed when I ask "how do you access the motor in the furnace" and a third of the responses want to debate the proper word for a bearing and another guy wants to go off on some tangent about Harbor Freight.

We have a Suburban furnace and it's one of the ones with only the little plate with the Intake and Exhaust tubes on the outside. I'd much rather have the version with the large full cover that lets you do more "work on the furnace" labor from outside.

That's what I've got.

So the answer to all of this is: "You've got to pull the furnace assembly to get access to the blower motor".

Steve

[j-d]

Steve, I can't tell you how to access that furnace motor. You've got the manual, just follow it. We have a Suburban furnace and it's one of the ones with only the little plate with the Intake and Exhaust tubes on the outside. I'd much rather have the version with the large full cover that lets you do more "work on the furnace" labor from outside.
That "Zoom Spout Oiler" is my GoTo, but just about everything has limitations. If you can get in there, by all means Zoom Oil it. Odds are very good it'll be quiet again for years. But like Mex mentions, things have limitations. A blower motor from our Coleman Mach rooftop A/C sits in my garage in testimony to that. One day camping at the beach, NO A/C. Blower motor isn't turning. No problem I've got a Zoom Oiler. Apply Oil and at Runs. Next day, stuck again. Oil again. Repeat the Stuck and Oil, Oil and Stuck routine. Took it home, completely dismantled the motor. Cleaned and polished Shaft, Bearings (Sleeve/Oilite/Bushing/Whatever), Oiled and Assembled. Good to Go? ***NOT*** I ran a bench test with Motor running on a Power Supply, Squirrel Cage Mounted... and it STUCK. The "bushings" don't seem to be a "bronze" material, more of a "steel." I can only figure the "steel" is porous and it's contaminated with something that turns Oil to Glue.
I'd actually drilled the rivets out of the bearing retainers to remove, soak, clean, and oil the bushings. Put it all together, installed it, and Ordered a New Motor. Had it shipped to our next campground and installed it there, replacing the one that was already stuck again.
So Steve, if you can ever get access to the thing, I'll give you 75% that Zoom Oil will cure it. But no more than that. Consider the value of your time. People tell me that all the time, and I still waste a lot of time.
But ABOVE ALL, this is a Furnace. Be sure nothing is rusted through, it all fits together right, you can get correct gasket wherever needed and so on!

[MEXICOWANDERER]

**** I tried balancing a 45 lb Oxford dictionary on my lap and failed. Better to avoid the Syntax Police...

Oilite Bushings. I promise in the morning to reach for the phone and gave them the bad news. Gettin' right on it.

[time2roll]

To reach in with a half drop of lubricant I use a clock oiler.

https://www.amazon.com/Creative-Clock-Oil-Kit/dp/B0089SKKY6

[Boon_Docker]

OUCH !

[John_Joey]

maillemaker wrote:
I just want to know how hard it is to pull the furnace out or if there was an easier way to get at the motor to lubricate it.

Steve

Couple of post prior I gave you a clicky to the zoom spout oiler. What you can't tell is that the thing pulls out about 12 inches and can get into just about any tight space.

Don't get any easier, and it's what I do after I got a squeal a few years back and now do prior to the season starting.

BTW, don't get snippy with posters. If you knew everything you wouldn't be asking these dumb questions.

[maillemaker]

Geeze the semantic games here.

I just want to know how hard it is to pull the furnace out or if there was an easier way to get at the motor to lubricate it.

Steve

[wolfe10]

mike-s wrote:

wolfe10 wrote:
First, the fan has BUSHINGS, not bearings.

A bushing IS a bearing, of a specific type, AKA "plain bearing", "sleeve bearing", etc. Bushings are bearings, but not all bearings are bushings. (ignoring suspension bushings which are completely different)

Mike,

Thanks for the terminology correction. When most people talk about lubing bearings I suspect they are picturing what I was referring to as bearings.

What would be the proper term for them to understand that these are "sleeve bearings". Not sure that term is widely known.

[mike-s]

wolfe10 wrote:
First, the fan has BUSHINGS, not bearings.

A bushing IS a bearing, of a specific type, AKA "plain bearing", "sleeve bearing", etc. Bushings are bearings, but not all bearings are bushings. (ignoring suspension bushings which are completely different)