I started noticing a really bad squeaky sound coming from the
furnace. It usually happens right away when it kicks on, then goes
away after it has run for a while (but sometimes it will start at
I assume I need to oil something but I'm not sure what and what type
of oil to use.
1. Motor bearings need oil -- 10W30 motor oil will work. Use a pump
oiler with a long spout to reach:
a. Bearings (2) on motor
b. Bearings (2) on shaft ends of fan, if belt driven..
You may have to loosen things to pull the fan assembly out so you can
get at it.
2. Slipping fan belt, if so equipped. There should be a tensioning
screw or other adjustment. Set so firm thumb pressure depresses belt
about 1/2" It also sometimes helps to use "belt dressing" on the
I keep a spare belt on hand at all times. Size is stamped on the top
(outside) of the belt. Any good hardware or auto parts store.
Check belts and/or bearing twice a year. Check burning/pilot light at
same time. I check at the beginning and the end of the heating season.
Do filters monthly. Consider a "washable" filter and spray-filter oil
for better dust pickup.
I see two fans in there.. One is smaller and is connected to the
exhaust, and one is a larger squirrel cage.. Which one do I need to
oil? Of course, now I can't get it to make noise again so I don't
know exactly which one the noise is coming from.
The larger fan looks like it would be quite a chore to pull out..
There are various other boxes mounted in front.
You would need to oil the motor that is squeaking but the high
efficiency furnace you have most likely does not have oil ports.
Usually a squeaking noise is caused by a pending bearing failure which
results in a motor failure. Nothing you can do about it unless the
squeak is something else.
It started squeaking again. This time I took off the cover and was
able to confirm that the sound is coming from the smaller fan attached
to the exhaust. This makes me worried.. If this motor fails, will I
have a basement full of CO2?
Well, I have good news and bad news.
The bad news is, your home is already full of CO2.
The good news is, you home is already full of CO2.
Luckily your home is NOT full of CO.
If the inducer quits, the pressure switch will sense this and shut off
Get the motor replaced.
Hey junior Jim,
In case you havent been around the last 20+ years or so,
..........................Inducer motors dont have oil ports. You get
a built in "xx" amount of hours out of them and then you replace them.
Car engine gets hot enough to drive the moisture out. Common knowledge among
techs. Here is your citaton:
"Heating techs have known for many years not to use detergent oils for
electric motors. The detergent oils absorb moisture from the air. The oil
then foams up, rusts iron or steel berrings, and loses lubrcity. Electric
motors do not get hot enough to drive the moisture out of detergent oils."
My old clunker had oil cups on the blower and oil ports on the motor,
newer stuff is sealed bearings you cant oil. Maybe a loose belt. I
think any oil is good, except cooking oil, although once as a kid I
put mazola in the mower. Oil if you can but sound going away sounds
like a belt if you have one.
Stand by the furnace until it starts and figure out the source of the
noise. If its the motor 10/30 motor oil on the motor bearings should
work. A car's engine runs a lot hotter than you furnace so it will
If not and you have an old style gas furnace with a squirrel cage
blower the bronze bearings are probably shot. They are quite easy to
remove and to replace. A HVAC supplies shop will have replacements.
They should cost less than $20. Check the cage shaft too to see any
scouring. Replace the shaft or shift it sideways to present a good
round shaft surface to the bearings if that is possible. The shaft and
bearings are meant to run dry. Grease will dry up in the heat and
cause problems. Oil will create an abrasive slurry with the bronze
bearing shavings. Even if the bearings are not the problem $20 is a
very cheap investment and resets the condition of your bearings for
another 20 years of trouble free running.
The squeaking we get here was actually the blower body vibrating on the
bolts that held it in. Put a hand on it, it'd stop. A little oil
around the screws & it stopped. Comes back abt every three years or
so; pull dust off, oil again.
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