lubricate sealed bearings


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Old 04-25-08, 02:30 PM
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lubricate sealed bearings

Hi guys,
I read through most of the threads I could find with the 'Search' function but couldn't find exactly what I came for.

I have a (about) 14 year old trane xl80 with blower trouble. The fan will start spinning only from a hand start. I replaced the run capacitor for new but this didn't help. I measured continuity for each wire to neutral (all good) and checked all wires to case for proper open (not shorted, all good).

I measured the voltage to Heat Low and it reads just over 120vac to the blower at the correct time.

The motor shaft has no wobble at all. There are no oil cups with this model.

I believe that the problem may be in the bushings (bearings?). The blower will only spin by hand for 3 to 4 revolutions (wires disconnected).

Q. This should be more like 20 revolutions, yes?

If so:
Q. Can I lube the sealed bearings or replace them?
For the cost of a new motor, I am happy to try to refurbish this one.

Q. Is there something I should try before taking the motor\blower housing apart?

Thank you for any assistance.
 
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Old 04-25-08, 03:52 PM
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Fan Problems

Have you checked amp draw? Even new capacitors are sometimes bad, rarely but sometimes. When replacing the cap did you just replace with the same rating as was there or did you check the label on the motor?
 
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Old 04-25-08, 05:38 PM
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Have you checked amp draw?
Do you mean measure in series with the run cap to check that it works?

I did do the 100 watt light bulb test and both fared about the same (7 and 7.6 vac for 5 microFarad). That should be a good test.

I guess that 3 to 4 revolutions is ok then?

did you just replace with the same rating as was there or did you check the label on the motor?
Good point. There is no information on the wiring diagram. If the information is labelled on the motor, it is going to have to wait a few days before I tear it out again. I was hoping for any other suggestions I might try before going back in.
 
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Old 04-25-08, 06:02 PM
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Amp Draw

Using a clamp around ammeter, with the motor running check the amp draw vs the motor rating. The only problem with this is a bad cap would cause high amp draw.
 
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Old 04-25-08, 10:55 PM
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Thank you Grady for the advice.
I'll pull out the motor again tomorrow, have a look at the rating and take a current measurement.

Out of curiousity. Do you know what resistance will show on the run cap wires to the motor with everything disconnected? I should be looking for an open or short there too.
 
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Old 04-26-08, 05:00 PM
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Cap resistance

If you have an analog ohm meter, set it on the 1K scale. Be sure to discharge the capacitor & put a probe on each terminal of the cap, then reverse the probes. The meter should show full scale deflection then drop back to reading an open. All this tells you is there is some capacitance there but does not tell you how much. There is a way to calculate capacitance using a test cord & clamp on ammeter but unless you are VERY comfortable working with electricity, I don't suggest you try it. Some digital multimeters have a capacitor test function.
 
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Old 04-26-08, 05:03 PM
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New developement:
Unless you advise me otherwise, I believe that I need to buy a new motor. I threw on the furnace today to get a current measurement (it looks to be around 7A), but now the fan is turning very slowly.

Before I do this, can I apply 120vac directly to the Heat Low and Neutral wire with the other wires disconnected via a wall plug? I want to make sure that it is the motor and not a bad voltage from the controller.
 
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Old 04-26-08, 05:10 PM
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Seven amps

Seven amps does not sound unreasonable but this sounds more & more like a capacitor problem.

If you make sure all the other wires are disconnected & taped or otherwise protected from touching each other or ground, yes you can test via a wall plug. I do it all the time.
 
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Old 04-26-08, 05:11 PM
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Posted at the same time
If you have an analog ohm meter, set it..
Know this one. I meant what the cap wires into the motor look like for impedance.
but unless you are VERY comfortable working with electricity
I used to work 13800vac, hot. If you wore a plastic hardhat your head would buzz!
 
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Old 04-26-08, 05:16 PM
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sounds more & more like a capacitor problem
I will pull out the fan right now and make sure that it should be 5 micro, like you suggested.
 
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Old 04-26-08, 05:40 PM
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Capacitor testing

Caps have two ratings. Microfarads & voltage. You can use a 440 volt in place of a 370 but not the other way around. Microfarad rating has to be within 10% of what is called for.
All I carry on the truck is 440's.

I'll send you a private message with the test procedure & calculation. This isn't something I want to put on a public forum.
 
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Old 04-26-08, 06:09 PM
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Ok, a little closer.
The motor tag reveals that the cap rating is fine.

60Hz 1phase
115v 5.8A 1/3HP
Cap 5uF 370v

But, away from the furnace, the blower is running for both caps. Albeit it was very slow beginning for the first start up and then it was fine for the second, third, fourth try. This was the same for both caps. I am guessing that the controller steals that little juice (in internal loss or wiring, whatever) that makes the difference between hang or run.

The motor should be spinning with a lot less effort than this anyway.

I can't get another run cap until Monday. I know that 99% of the time, this cap is the problem when these are the symptoms. And that is why I replaced it first as mentioned in my first post. But I have seen both caps charge up in the 100w bulb test and level off to about the same voltage in this voltage divider. A level which corresponds to proper tabled results. I don't have a capacitance meter.

I would love this to be a $7 (another new run cap) fix but I am guessing that I am not that lucky this time.

edit: Missed your last post. Thank you. Will wait for your PM.
 
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Old 04-26-08, 06:22 PM
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Probably a motor

Since you've done the light bulb test, both caps seem to be doing the same thing, you don't have a capacitance meter, & I can't find that danged formula, we may have to resort to replacing the motor. I hate to change parts without knowing for sure they are bad but sometimes the process of elimination points to a part as it seems to here.
 
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Old 04-26-08, 07:23 PM
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I can't find that danged formula
I sent you some info in a PM.


Grady, I appreciate your efforts.

This is the pearl of wisdom I just got from my wife. Going to quote this one:

We got 14 years out of that motor. Just go buy a new one.
You want the house to burn down?
Valid point.
 
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Old 04-26-08, 08:29 PM
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Smart Lady

You'd better hang on to 'er.
 
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Old 04-29-08, 12:27 PM
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I had intended to replace the motor but when I took it out, the bearing (shaft end) was full of long hair. I backed the hair out and add a few drops of lubricant and it works again with the original run capacitor.

My wife did report that she smelled a burnt plastic smell in the house when the troubles began. Is there any chance that the stator is permanently damaged because voltage was applied without the rotor turning?

I wonder how long it will last because this is the sealed type of bearings.
 
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Old 04-29-08, 05:56 PM
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How Long?

Your guess is as good as mine or anyone else's. I've seen them last years & others crap out in a few days.
BTW, I found that formula. Check your PM's.
 
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Old 04-29-08, 07:26 PM
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The lube made a hugh difference.

The wife is ok with it as long as the furnace will shut off should it happen again. If it does, I'll replace it for sure.


Sent a PM.


I made notes on the furnace spring clean that I did. I scrounged some of the information from posts at doityourself.com and some around the net. I thought that it may be a good primer for the beginner. Should I post it on the forum or would it be a waste of web space?

I didn't see anything similar here but I may have missed it.
 
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Old 04-30-08, 03:05 PM
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Furnace spring cleaning

Go ahead & post them. I suggest you do so in a new thread. I & others will probably add to or make alternative suggestions.
 
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Old 05-02-08, 03:57 PM
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The administrator may allow you to use the attachment feature of this forum, which gives you the ability to attach files of certain types to your posts. This could be an image,
Grady
Do you have the bars to make it so?
 
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Old 05-04-08, 11:25 AM
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Originally Posted by Squeeto
Hi guys,
Q. Can I lube the sealed bearings or replace them?
For the cost of a new motor, I am happy to try to refurbish this one.

.

Adding some 20 weight to a sealed bearing may make a temporary improvement. If it does, it most likely will be very temporary, and you need new bearings.


Any motor can be overhauled, but it is a matter of time, knowledge, special tools ( bearing oven and press) and especially the availability of parts. I can just about guarantee that Trane or any other furnace maker, does not stock replacement bearings. You could take it to a small motor repair technician, who has the tools and knowledge to replace the bearing and also make sure the motor is electrically OK. I would guess a new motor would be in the $150 to $350 range....depending partly on whether you get an OEM or a replacement from Fasco or Grainger. I can't imagine that you could get the old one repaired for less.
 
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Old 05-04-08, 12:29 PM
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bearing oven and press
I have neither.
I probably should price out a replacement motor before winter. Right now the over-night temperatures are good.

I will get as much milage out of the old motor as I can (until it acts up again).

It would be useful to learn to rebuild it though (assuming parts are available). I used to repair circuit boards for equipment where my company would pay a core charge for the clients old board. The client would pay $100 or so for a new (refurbished) board, get back $10 for his old and I would spend 10 minutes and $4 in parts and fix it. I wonder if motor repair is similar?
 
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Old 05-04-08, 12:53 PM
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For the fun of it, I'll call local motor shop guy who I have bought lots of furnace or heat pump motors from over the years, and ask him, based on your specs, what he'd charge for one. Presuming you have about a 1/2 inch D-shaft? I know I have gotten 3-speed motors (you hook up the speed you like, that is printed on motor, which hot wire to use/speed output in rpms) from him for quite reasonable - like under $120. I have gotten motors from him as low as about $85 (may have been 1/5 hp, though). And I haven't had to go back and replace them.
 
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Old 05-04-08, 09:36 PM
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quite reasonable - like under $120
Good price. I'll bet that it is twice that here though (Vancouver Island, Canada).
 
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Old 05-05-08, 07:16 AM
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I just called up the shop and owner said off the top of his head it be about $80. I said, "For a 1/3 horse?? He said, "yeah". He said he knew they are under $100 for sure. I even read him all your numbers. He asked me if it was direct drive and I said I think so. Advise further regarding if this is right, and perhaps what Canadian laws are for shipping/costs across country lines. !!

Have you looked online for replacement and shipping costs?
 
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Old 05-05-08, 10:49 AM
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Yes, it is direct drive and I don't recall the hp.
Have you looked online for replacement and shipping costs?
[/Begin Rant]
I have gotten good at this now having to do the 10 year, 100Km maintenance on my car.

eg:
-$tealership price for new CV = $670 Canadian
-aftermarket or OEM CV from local independants = not available
-refurb. OEM halfshaft with 2 new OEM CVs including shipping from USA = $170 US
[/End Rant]
 
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Old 05-05-08, 12:07 PM
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Find out shipping cost, and that shop here could send you one.
 
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Old 05-05-08, 01:54 PM
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I phoned around and found THE shop to see in town.
I will have to bring the motor in but the salesman thinks that it will be around $100. I can't get it to him for a couple of days though.

Thank you, Ecman51
Any idea who the administrator for the forum\thread is (see post #20)?
 
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Old 05-05-08, 03:44 PM
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"Sharp Advice", administrator.
 
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Old 05-05-08, 03:50 PM
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Posting pics

Sorry for the delay, I've been just a bit on the busy side the past few days & haven't had a chance to get online.

I know there is a way to do it but I know not how. I do know when pics are posted directly on the board & you have dial-up, it takes forty forevers for the thread to open. I suggest posting pics on photobucket.com or similar photo hosting/sharing site & provide a link to them here.
 
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Old 05-05-08, 08:52 PM
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"Sharp Advice", administrator.
Nope. Wasn't trying to get better advice; you guys have been perfect. Just wanted to post some info and it really needs some small .gif files added in.
posting pics on photobucket.com or similar
These sites usually ditch your pics after a while. It is too bad we can't do it here.

Grady, to date, you have 7901 posts. They should give you admin rights.
 
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Old 05-05-08, 09:04 PM
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Sent PM to Administrator.
 
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Old 05-06-08, 06:42 PM
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pics

From what I've learned there is an "attach image" function in the tool bar above. It is the next to last button on the second line (Yellow square with picture of mountain). Hope this helps.
 
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Old 05-14-08, 08:41 PM
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Over one week wait and no reply to PM to Administrator.

No further action.
 
 

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