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Noisy Furnace Fan


oldjohnt

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I'm sure anyone who has owned as many or especially older RV's as I have has experienced this problem before.

 

Darn Furnace Fan has started that temporary (on start up) dry bearing high pitched squeal grrrrrrrrrrrrrrrrr Ima thinkin its those Oillite bushings and I'm NOT into removing and soaking in hot oil and all that stuff.

 

Are there any home spun inject with lithium grease or oil or lube to cure the problem or does it need a new fan (assuming Im not into the whole re lube in hot oil bushing thing). Its an Atwood furnace (forget model) so how tough is it to replace the fan??????????

 

It just started a few times but needs fixed before we head South because the colder it gets the worse and longer the squeal in my experience.

 

It never ends

 

John T Live from Austin Texas and headed back soon to Indiana

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The motor needs to be replaced. I've replaced two motors since since we began full timing in this rig in 2002. It's not a bad job but it does take some time. The unit does not need to be removed from the rig. All the work is done from the outside. A set of T handle allen wrenches makes the job of removing the squirrel cages a lot easier.

 

I paid $87 for the motor at a local RV dealer in Mesa, AZ last year. I'm sure you could do better by ordering online. There are many different models so be sure you get the correct one for your specific furnace.

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Thanks Rif, I like the idea it can be done WITHOUT removing the furnace. I knew of a guy who (claimed to) boiled the oillite bushings in a certain oil for a certain time and temp, but I think I best if I track down model and part number and shop for a fan BEFORE we head to Florida for the winter. I don't recall one curing itself once they start that death squeal...........

 

John T

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This might be different , but our fan was squealing badly and I found that the fan wheel was simply rubbing on the metal housing plate ( located on the right side next to the burner ) . I simply drove a screw through the plastic fan housing at an angle so it applied pressure to the metal plate . That pressure is enough to push the plate far enough away . We now have a quiet furnace .

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Too much of an aggravation to try home remedies on the bearings, get a new motor and swap it out.

 

X2... and the home remedies generally don't last for very long. You can generally find a deal more in the $60 range so it's not very cost effective to baby it along. You KNOW it's going to be dark 0:30 when it starts squealing again. ;)

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Try to get it fixed ASAP. We let ours go and of course it failed entirely during the coldest weather on a trips 2,000 miles from home. Then the repair shop had to order parts and work us into the workload. Real pain to deal with while on the road.

 

rocmoc n AZ/Mexico

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I agree with the others, replacement is the only recommended long term remedy. I've salvaged another week or two out of squeelers with an needle oiler a couple of times over the years while I waited for a replacement motor to arrive, but that's hardly worth the effort if you have the opportunity to fix it before you really need it.

 

The motor replacement itself is not terribly difficult, and assuming you have a common 8500 or 8900 series furnace, the instructions given in the manual linked below are pretty good. The instructions are written for a motor upgrade though, so ignore the wiring changes and use the mechanical descriptions as a guide. Your specific model may have some slight differences, but that should be obvious and easy to work around.

 

hydro flame Service Manual

(see page 14, PDF page 12)

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It's not a bad job but it does take some time. The unit does not need to be removed from the rig. All the work is done from the outside.

That depends upon the make/model of furnace you have. Atwood and newer Suburban furnaces this can be done from the outside, but some of models of Suburban and all older Suburban furnaces must be removed from the RV to do this because of the lack of outside access. The Suburban in our 2012 KZ has no outside access.

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That depends upon the make/model of furnace you have. Atwood and newer Suburban furnaces this can be done from the outside, but some of models of Suburban and all older Suburban furnaces must be removed from the RV to do this because of the lack of outside access. The Suburban in our 2012 KZ has no outside access.

 

Absolutely right, Kirk, but since the OP said his was an Atwood I told him he could replace the motor from the outside. Still, no harm in pointing out the fact that it is not always possible, depending on the make and model you have.

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Absolutely right, Kirk, but since the OP said his was an Atwood I told him he could replace the motor from the outside.

I missed where he said Atwood. You have to go back a long way to find an Atwood that don't have outside access, but some of them can be a major challenge to change even with that access. I've not forgotten one that I agreed to help change and help turned into doing most of it. There was nothing easy about it. That was one from the early years and while it was possible, it sure taught me a very expanded vocabulary of expletives! :P

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I missed where he said Atwood. You have to go back a long way to find an Atwood that don't have outside access, but some of them can be a major challenge to change even with that access. I've not forgotten one that I agreed to help change and help turned into doing most of it. There was nothing easy about it. That was one from the early years and while it was possible, it sure taught me a very expanded vocabulary of expletives! :P

 

Atwood still makes the "Everest Star 7900" series furnaces that are inside access only. They only go up to 18,000 BTU/h though, so they're usually only found in smaller RV's. They can be a PITA to work on!

 

http://www.atwoodmobile.com/furnaces/everest-star-7900-ii-series.asp

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Its an Atwood Hydro Flame Excalibur Series 8531-IV-DCLP. Im finding the blower motor on Amazon and a few other sources but unsure if it takes a 37696 or 37698 motor so I e mailed Atwood with the numbers and asked them.

 

Thanks again guys. Yep Im gonna go ahead and replace it when were home before we head south

 

John T

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Its an Atwood Hydro Flame Excalibur Series 8531-IV-DCLP. Im finding the blower motor on Amazon and a few other sources but unsure if it takes a 37696 or 37698 motor so I e mailed Atwood with the numbers and asked them.

 

Thanks again guys. Yep Im gonna go ahead and replace it when were home before we head south

 

John T

 

John, your 8531-IV takes a 37697 motor. The 37696 fits an 8520, and the 37698 fits an 8535. Luckily, the 37697 seems to be the cheapest of the three on Amazon... :D

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Having a working furnace isn't what most of us would consider to be a 'nice to have' expenditure, but rather a necessity going into the winter months.

 

LOL ... Obviously . I consider replacement , if all else fails . So , unless all else has been investigated ...

 

And , don't you really mean ' a quiet furnace ' ? :D The squealing got to me , too . ;) But , we still had heat .

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Too much of an aggravation to try home remedies on the bearings, get a new motor and swap it out. Then you can play with the old motor and if you ever get it better you have a spare for when the new one has issues.

 

X10.......

The real problem is that the oilite bushings are subject to very local high-overhung-loading due to the short bearing span compared to the long fan / shaft length........in other words ........very poor design for reasonable service life however great design if replacement profits are the company goals........

 

The reason that re-lubing the bushings don't work is that the howling noise not comes from lack of lube but too much clearance between the shaft and the oversize worn bushing bore.........IF you lube it enough you might inject enough lube to temporarily dampen the shaft wobble but it will come back as soon as the dampening agent is expelled.......

 

Remember.......... part of the "RV-experience" is the .............."experience" we gain repairing things that we did not know that we could repair in our non-RV-Lives...........

 

We keep a Big Buddy heater handy for the times when the furnace is...........in "RV-mode" (not operational)

 

Keep a spare furnace motor in the big box with the rest of the vital RV-Spare-Parts we carry...........

 

Drive on..............(Keep your Big Buddy heater handy........)

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If Atwood is counting on my own replacement motor purchases to enrich them, they're not making out very well. I replaced the original fan motor in our '95 Coachmen after thirteen years of service in 2008. The original two fan motors in our current coach are 14 years old and still going strong... And squeal free so far... I don't carry a spare motor or other furnace parts because just one of our two furnaces is capable of keeping us warm down to about zero or so. That leaves the other one available to borrow parts from when needed until replacements can be secured. Running both of them does give us a more even heat though.

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If Atwood is counting on my own replacement motor purchases to enrich them, they're not making out very well. I replaced the original fan motor in our '95 Coachmen after thirteen years of service in 2008. The original two fan motors in our current coach are 14 years old and still going strong... And squeal free so far...

We had two Atwood furnaces in our fulltime motorhome and it was 14 when we sold it, still with both furnaces all original parts.

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THANKS YAROME Well I have to say that's indeed a "heater"

 

BUT THE PLOT THICKENS

 

Dutch noted above my 8531 - IV Hydro Flame Furnace takes a PN 37697 Fan Blower Motor

Amazon shows it takes a PN 37697 Fan Blower Motor

 

But I sent 2 e mails to Atwood and they both say it takes a PN 37636 Fan Blower Motor????????????? I think that's a Model Number for a whole other 37636 Furnace. Seems hard to believe I have to trust Amazon more then Atwood?????????????

 

Last 2 days it hasn't squealed but Im gonna buy a new motor anyway to be prepared.

 

John T Leaving Austin TX today heading home, Im road weary from all that mountain driving. After this trip the drive to Florida is like nothing

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I would go with the 37697. It jives with the atwood manual, and checking 3 other parts places all jive with amazon and Dutch. All 4 places list the 37636 as a complete furnace unit. There is no reference I can find to correspond to a part number. It looks like amazon has the best deal by a couple bucks + free shipping. If anything.. I would purchase through them simply because their return policy is bar none.

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