Furnace howls

[rich85704]

It's getting to be warm here in Southern Arizona, but it still seemed like a good idea to check the furnace in my new (used) 1999 Santara 23RB Class C.

Howls! Banshee-like howls and screeches! Sounds like a bearing issue? Or does something need lube? There isn't a trouble-shooting guide in the manual.

I think it's an Excalibur 8500 or 8900.

Any experience with this? Ideas?

R

[j-d]

I really like Turbine Oil aka Zoom Spout Oil. Amazon search will turn it up. The oil is good and spout gets into tight places.

[rich85704]

I spent some time with the rig this afternoon. Took the cover off the furnace: it's an Atwood 8531-IV-DCLP. Poked around a little, but taking it apart was pretty intimidating. I started it up, and after a short (20 sec?) howl, it ran quiet and seemingly smooth. Man, that baby pours out heat! I shut it down long enough to put the cover back on, and cleaned up from some other work. Turned it on again, and it started right up and ran quiet from the git-go.

I had the same thought as JaxDad about letting it howl, but now I'm wondering if maybe the problem has taken care of itself. Previous owner says he didn't remember any strange noise.

So even though extra heat is the last thing we need down here in southern Arizona right now, I'll start it up regularly when I go to work on other things. One thing seems clear: it this needs intervention, I think it's gonna be from a pro. This has passed my DIY threshold.

Thanks, all.

Rich

[JaxDad]

wolfe10 wrote:
Strongly recommend AGAINST 3-1 oil. It increases viscosity with time.

A light, non-detergent oil such as sewing machine oil is much better choice for the fan motor bushings.

Actually, 3-in-1 'electric motor' formula is designed for exactly this use.

I would however highly recommend against just letting it howl. It's a sign the bearing is dry and the shaft is bouncing around within the clearance that should be taken up with lubricant. That bouncing and friction will dramatically increase the wear.

[wolfe10]

Strongly recommend AGAINST 3-1 oil. It increases viscosity with time.

A light, non-detergent oil such as sewing machine oil is much better choice for the fan motor bushings.

[ksg5000]

As others have mentioned oil sometimes works ... sometimes just letting the fan run continuously for a while will cure the problem, in my case I started up the furnace then turned off the propane and let the furnace run for about an hour - haven't heard the squeal in 3 years. If those don't work then your going to need a new motor.

[JaxDad]

Yup, dry bushings, mine did the same.

As mentioned above, a few drops of 3 in 1 'electric motor' formula will cure it right off. It's now on my annual 'to do list'.

[darsben]

PB Blaster

[Old-Biscuit]

Sealed bushings on fan motor. A little 3 in 1 oil might??? help.

Could be debris in air wheels (room side and or combustion side)
Or could just be time for a new motor

Here is a service manual. Exploded views of various models start on pg. 39.......LINK