Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

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Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

November 22, 2017, 12:59:45 am

Fan on the propane furnace started squealing this week - most times minor but every now and then the squeal is severe for a minute or two. Old forum searches lead me to believe that a bushing has run dry. Sounds like the temporary fix is to oil to bushing, but maybe the better long term solution is to replace the fan motor. I opened it up today with some sewing machine oil - but I've never been in a fan blower assembly before and I was unsure where to oil.

1) Could anyone provide assistance as to where exactly I should be adding oil? Any visual aids would be much appreciated.
2) Is fan motor failure imminent with a dry bushing, or is it more of an auditory nuisance for a while? I asked because I'll be back on shore power in about three weeks, which would be an ideal time to replace the fan motor, but the propane furnace is our only source of heat (without firing up the generator) until then (we full-time). Would I be taking an undue risk waiting that long?

Thanks for the help!

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #1 – November 22, 2017, 06:13:03 am

I have an 01 and had the same problem tried to oil Motor ended up being one end of motor bearing gone replaced at MOT

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #2 – November 22, 2017, 07:16:46 am

Find shaft of blower motor. Might have to remove fan (squirrel cage?) from shaft lithium grease may be better but oil will work just 1-2 drops. I have same squeal returned from Illinois 2 weeks ago. Its on my list. Perhaps a well aimed slide lube would resolve problem? Yes its on my list also

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #3 – November 22, 2017, 09:27:23 am

Fan squeal is not a emergency...just a irritation. It's not going to blow up or start a fire...I don't think.

The motors on those heaters have sealed bearings/bushings. There is no way to really get lube into the bearing. You can remove the motor, hold it in a vertical position, put very thin oil on the shaft, and rotate the shaft with your fingers. Sometimes that will loosen up the bearing and cure the squeal. Excellent for this purpose is Zoom Spout oil - sold in most hardware and big box stores:

Highside Chemicals Inc. manufacturers the Zoom-Spout Oiler.

Oiling the shaft is probably not a permanent fix for the squeal. It may return, with a vengeance. If you are going to all the trouble of removing the motor, I'd just replace it with a new one. See thread linked below;

Replace Atwood furnace fan

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #4 – November 22, 2017, 09:38:37 am

Thank you very much!

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #5 – November 22, 2017, 09:43:44 am

I have even gone so far as to use a cheap hypodermic injection needle and pushed the tip thru a bearing seal in order to get the bearing or bushing oiled.
Usually, if bushings are used they are almost always Ampco bronze or similar--which is an oil impregnated bronze for lubrication.
We were way back in the "boonies" and it was a holiday weekend about 40 years ago so---nothing open anywhere back then, and we did need heat because of our kids.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #6 – November 22, 2017, 10:05:07 am

If you decide to remove the motor for any reason, photo below may help. It kinda shows what needs to be unhooked to get the motor out. I was replacing the circuit board, motor and the burner, so I had it pretty much all ripped apart. It's a simple job - just need a few basic hand tools. A set of long-handle allen wrenches would be nice to have. There are two plastic covers over the motor. The outer cover drops down, and the inner cover lifts up. Some wires to disconnect. Be careful of the sail switch (on the inner cover) - it is kinda fragile. The fan is held on the motor shaft with a set screw - it will probably be very tight. If you don't remove the burner, then you can't slide the fan off the motor shaft. In that case, you might need to remove the circuit board so you have room to move the motor to the "left" to remove it.

This will all be obvious when you actually get in there.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #7 – November 22, 2017, 08:29:11 pm

First time I turned on the furnace it screamed like a banshee. I immediately ordered a new motor, about $50. Then I tried oiling the motor shaft bushings, WD40, Spray silicone, Spray white lith grease, more WD40. You can wiggle the shaft back & forth a little to work the oil in. The WD40 helps thin & transfer the oils into the bushing. My theory anyway. Has worked without a squeal for 2 years. New motor is still in the box.
On to the next project. Cheers Ric

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #8 – November 22, 2017, 08:49:04 pm

WD-40 is not the best choice. A light-viscosity machine oil is what you should use. Sewing machine oil is one choice. Some hardware stores sell the correct oil with a LONG delivery nozzle that works very well.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #9 – November 23, 2017, 10:28:57 am

Remove furnace motor, orient the motor in the correct position in a vice, drill 1/8th. hole in each endbell ,lubricate with turbin oil, this will add oil to the wick, I did mine 6 years ago and it is still working, did the same the to both AC motors.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #10 – November 24, 2017, 08:02:07 pm

Thanks everyone. Grabbed some non-detergent 30w, removed the fan cover and fan blade, worked in some oil manually while turning the shaft (without removing the motor), and the problem appears to be solved!

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #11 – November 24, 2017, 08:31:17 pm

MMO Marvel Mystery Oil with a long motor lube spout, the oil will wick in real nice.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #12 – November 25, 2017, 08:45:23 am

Nevermind - ran smooth as silk for about 5 hours (and the squealing is still gone) - but then it started rattling terribly and occasionally grinding. I think I may have induced some play into the fan drive shaft while I was fiddling around in there? Time to find a campground, plug in, and switch to electric heat while we figure this out -- it's 26 outside this morning!

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #13 – November 25, 2017, 09:48:53 am

Sounds like the introduction of oil caused the glaze on the bushing to "disappear" which then increased clearance between the shaft and the bushing.
Solution? new motor or do a rebuild if the motor shaft is in good shape yet. If you go that way, make sure you get Ampco bronze Oilite bushings. They are impregnated with lubrication fluid.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #14 – November 26, 2017, 02:20:07 am

Hm, I am facing the same problem and took the motor out a while ago to check on the issue. I believe the squealing sound in my case did not stem from the motor itself, but from the plastic blower wheel on the right. It did scrape against the housing. The motors shaft seems to have a play on mine f about 1/16th and I guess that's due to wear. Something I'd like to try is to add a plastic washer inbetween the plastic blower wheel and the motor.
It's just an idea, but the squealing noise I have is too loud to be caused by the bearings.

Just a side note as you're working on the furnace already: The furnace uses a sail-switch that detects if the blower is working. In case the blower slows down for whatever reason (fault), the sail switch will disengage and gas flow to the burner will be stopped. If you order a new motor, try to get this switch too and put it to your spares. If this switch fails, there's no way to operate the furnace safely.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #15 – November 26, 2017, 07:37:51 am

I think the motor comes in with a bit of horizontal play along the shaft in and out, and that is normal, but shouldn't move on any other axis. Good advice on the switch - I checked my spring loaded "blower detector" and it seems to be in great condition so I think I'll leave mine for now.

The fan on the right is the combustion fan. From the instructions I read and videos I watched, the technique for getting that to sit correctly in the housing was to set and tighten the blower fan on the left before tightening down the combustion fan on the right. You should be able to slide the combustion fan on the shaft to a location that won't hit the housing on either side of the horizontal play of the shaft. You can manually test this before hooking everything back up as well. I also noticed a slotted screwhole on the housing on the combustion fan side that should allow you to expand the housing slightly if there just doesn't seem to be a way to prevent the fan from hitting the housing. But this is all theoretical - Should be able to confirm or deny that on or around Tuesday when the new motor comes in.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #16 – November 26, 2017, 09:09:45 am

Try spraying the plastic fan outer tips of the blades with dry silicone spray. If noise stops the problem has been identified.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #17 – November 26, 2017, 09:31:18 pm

Took the blower motor out tonight in anticipation of receiving the replacement tomorrow or Tuesday. I was worried because when I took the blower fan cage off, the shaft on the fan side seemed like it was in fantastic shape. But when I got the motor completely out, the other end of the shaft (combustion fan side) was totally shot. Looks like we found the problem.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #18 – November 26, 2017, 10:17:56 pm

When I took my furnace apart, I found both fans were really dirty. Perhaps the dirt gradually accumulates on the fan blades and throws it out of balance, which then beats up the motor shaft support (bearing or bushing). However, the motor I replaced was original to our coach, so it lasted 20+ years. I guess I can't complain about that kind of service life!

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #19 – November 30, 2017, 12:36:54 am

Put in the new motor and all is working great still 24 hours later. Thanks for the advice everyone.

I also found this video very helpful: https://www.youtube.com/watch?v=kz9JEn9y6ZY&t

One thing that isn't really covered well anywhere was that the motor was very difficult to get out. I had a mechanical weld between the right fan motor drive shaft and the metal combustion fan. The blower fan is plastic and comes off easy, but the combustion fan not as lucky - plus the motor is built with some lateral play so it's hard to put enough force to remove holding just the motor. After a few hours of unsuccessful non-flammable sprays, heating/cooling rims, yanking, and percussive adjustment the following worked for me:

Vice grips on the left (blower fan) side of the drive shaft. long handled hex key / allen wrench into the sink screw through the combustion fan to keep it from spinning, and then you should be able to rotate the vice grips to break the mechanical seal and wiggle the drive shaft out (the combustion fan remains in the housing).

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #20 – November 30, 2017, 11:15:44 am

These furnace fan motors are $30-80 (depending on where you buy from, I got a deal on eBay for $25 new in box). Why spend the time taking apart, oiling, messing around, etc when you can fix the issue with a new part? The motors are cheap and not designed to last forever. The bushings and brushes wear out.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #21 – November 30, 2017, 06:49:54 pm

Quote from: krush – November 30, 2017, 11:15:44 am

I got a deal on eBay for $25 new in box

Do you recall the model number, and/or the eBay dealer?

Thanks,

Trent

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #22 – November 30, 2017, 07:11:19 pm

Quote from: TulsaTrent – November 30, 2017, 06:49:54 pm

Do you recall the model number, and/or the eBay dealer?

It was a 1 time guy that was selling random spare parts. He didn't have any extras.

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #23 – November 30, 2017, 09:03:58 pm

Quote from: TulsaTrent – November 30, 2017, 06:49:54 pm

Do you recall the model number...

Trent,

You can find the motor model numbers in the Atwood furnace manual. See the note on motors on page 23 (Circuit Breaker & Motor), and motor model numbers on page 47 (Part Reference - Motor). You need to make sure you order/buy the correct motor for your furnace model. Once you have determined the correct motor part number, do a Google search for price and availability.

http://bryantrv.com/docs2/docs/hflamefurn04.pdf

Re: Atwood Furnace Squeal. Where to add oil, and how severe is the problem?

Reply #24 – November 30, 2017, 09:39:47 pm

Got our's off Ebay

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