Hoover Convertible Motor Troubleshooting

[hooveru4089]

I have an older Convertible that runs perfectly smooth - except when I first turn it on after sitting. For the first few seconds of running after sitting, it sounds almost like dirt being picked up, but it is definitely coming from the motor as I hear this noise even if the base is up off the carpet when I turn it on. After a few seconds, the noise goes away and it just purrs. I did not notice anything obviously unusual when taking the motor apart and I have been regularly lubricating the bearings. Any input/troubleshooting tips would be greatly appreciated.

 

[vacuumlover]

Could be the possible start of warn bearings?

Or a slightly out of shape fan? eg. One of the blades slightly bent thus causing it to vibrate slightly upon start up?[this post was last edited: 3/8/2016-14:36]

 

[hooveru4089]

It is not quite a vibrating sound, and I have a washer between the fan and the bearing which should eliminate vibration. It almost sounds like a bunch of scraping noises inside the motor. It's not that loud at all; I just notice it and it seems to be progressing.

 

[vacuumlad1650]

Fans sound like they are rubbing mixed with bad bearings. They get mis-shaped over time of sitting

 

[kirbyvertibles]

maybe what you are hearing is the electrical arcing of the carbon brushes at first?

 

[hooveru4089]

@kirbyvertibles:

It sounds like that could be it. Is this something I should address soon? The cleaner runs fine otherwise, just purrs like a Hoover should.

 

[hooveru4089]

I should have mentioned previously that this is an intermittent problem; I used it yesterday and did not hear the noise.

 

[MPN]

Hi,

It's likely a stretched area on the belt, as the vibration/noise ceases after the belt warms up.

 

[hooveru4089]

@MPN: There is definitely not any vibration nor is this a vibrating noise. I don't mean to dismiss you, but it definitely sounds more like arcing, as kirbyvertibles suggested.

 

[MPN]

Does the noise change with the belt removed???

 

[MPN]

"I don't mean to dismiss you, but it definitely sounds more like arcing, as kirbyvertibles suggested."

Brushes arching on the commutator makes a "hissing" or sputtering sound if the brushes and/or commutator are really worn.

Another thought . . . If the brushes are really worn down to where the spring tension is greatly decreased, the brushes will bounce especially if the commutator is very worn or out of round. This would explain the noise at start-up, that diminishes afterward as the brush float dampens out.

 

[hooveru4089]

I sometimes do hear the noise when the belt is removed. It is definitely more of a "sputtering" sound or a bunch of little scraping sounds. How would you recommend that I go about diagnosing this? What should I check for?

 

[blknblu]

A mechanics stethoscope could be used to isolate the noise.


The end is is a long hollow tube. For electrical, I put a piece of clear tubing  on the end.


Have to be careful around electricity you know.


They are less than $5 at Harbor Freight ..


 

 

[hooveru4089]

Those tools sure are useful…

…but it seems pretty clear to me that the noise is coming from the brush/armature area. I would like to know if I should disassemble the motor and, if so, what I should examine inside the motor and what I should do depending on what I find.

 

[vacuumlover]

Could be a small build up of dust on the brushes/commy.

 

[hooveru4089]

How would you suggest I clean it?

 

[hoovercelebrity]

Can you post any pictures of the machine? How about a model number? Have you tried completely rebuilding the motor instead of hypothesizing about what's wrong? That's what I do with most all of my machines, and they all run very nicely.

 

[hooveru4089]

Here are some pics:

Close ups of armature, brushes and lower bearing. Motor was very dirty at first; I had to vacuum it out. The model is 719. Let me know what you think.

 

[MPN]

Hmmmmmmmmm ? ? ?

From shat I'm seeing in the first photo, the shaft seems to gave a blue tinge indicating overheating due to lack of lubrication. This could very well be your noise!

While you have it apart, if you have access to a lathe, check the commutator for out of round. If it is out of round, do a few fine cuts just enough to re-round it.

Oil the hell out of that Oilite-bronz bearing or bearings with synthetic oil prior to re-assembly.

Also, REMEMBER to re-install the brushes in the same holder and position as removed, so they don't chatter and/or ark . . .

 

[vacuumlover]

The brushes look like they have a slight chattering problem IMHO and they also look like they have over heated. The commy looks like it has slight threading and bar burning which would back up the statement of the brushes.

Also I on just seen your other comment. When there's q slight dust build up I just wipe the brushes and commy with a soft cloth.

And, if it's not too much of a problem, would it be possible to ser the brushes'"face" (that's what I nickname the part that touches the commy.)

If it has a slight line through it, that would also back up my statement of dust build up on the commy.

I don't know about anyone else but it looks like there's slight arcing too.

 

[hooveru4089]

Very interesting!

Now I wonder why the shaft is not getting lubricated. I have been regularly lubricating the sleeve bearing with 3-in-1 electric motor oil; first cleaning out the sleeve with oil soaked Q-tips and then placing a drop on each felt pad. Could there be a problem with the bearing?

@MPN: What should I use to machine the commutator? Fine sandpaper? I have heard of these electric motor commutator cleaning sticks. Would you recommend them?

 

[MPN]

Well, here goes . . .

"@MPN: What should I use to machine the commutator? Fine sandpaper? I have heard of these electric motor commutator cleaning sticks. Would you recommend them?"

Like I said: A lathe is the best method, if you have access to one.

If you're not going to take that approach, use GARNET or WET N' DRY sand paper.

NEVER USE EMERY or CROCUS CLOTH, as they contain metal that can short the commutator segments and destroy the armature!!!

Also, you'll want to burnish (slightly dull-down) the bearing surfaces on the armature shaft with a Scotch Bright Pad, until the blue disappears so lubricant is able to penetrate into the metal. At this point you have nothing to lose, as Oilite-bronz bearings are impregnated with oil at the factory, that overheating vaporizes away.

 

[hooveru4089]

More pics:

@vacuumlover: Here are the "faces" of the brushes. Hopefully this is clear enough for you to see, but from my perspective, they do look a little scratched up. BTW, the last time I ran the motor by itself without the brushroll and belt attached, the motor was somewhat noisier than it probably should be.

 

[vacuumlover]

Lovely. Thank you for the pictures. Yep, there's dust build up on the commy surface. Quite badly too as they are very scratched. This is causing poor contact with the commy thus causing excessive sparking.

In this case, what I do is ~ wipe down the commy with a soft cloth to remove any dust. Then what I do is use wet and dry sand paper. Starting with coarse and working to fine until the segmentation is gone. What I do to make it easier for the brushes to seat is try and rub the sand paper in a curving motion to try and keep as much shape of the brush as possible. (This makes it less faffing around to seat them)

Hope this helps

Also, it doesn't look like there's any chattering problems. Just over heating which has made the brushes "melt" In this case using the wet and dry sandpaper (just using a fine grade) is rub it evenly from the sides of the brushes.

If it's any easier I can try and get a video.

 

[hooveru4089]

@MPN: I might be able to get my hands on a lathe. Could I use Garnet or wet/dry sandpaper on the lathe or would you recommend something different to machine the commutator? Also, what specific type of Scotch Brite pad should I be using to clean the shaft

 

[hooveru4089]

@vacuumlover: Thank you for the tips. I am learning quite a bit of valuable info from this thread as I do not have much experience servicing electric motors beyond lubricating bearings. Do you use the sandpaper dry or with a liquid?

 

[hoovercelebrity]

If you use sandpaper, do it dry, I imagine.

I personally use commutator cleaning stones and have always had good luck with those; that's what we used whenever I worked in a vacuum store. There's one that is a rubberized abrasive stone which I use before I wash an armature - then I use a diamond seating stone after; before I reassemble the motor to polish the commutator plates. A Hoover Convertible is tricky, because you can't really get a brush stone into the running motor, as you can with other types of motors.

I would also recommend not over-lubricating your upper bearing, that could be causing some of the problem. You should be able to find a new upper bearing relatively easily - you may just want to replace it and be done with it. You might want to find a new pair of carbon brushes, as well.

 

[vacuumlover]

Always use it dry. Make sure you wipe /vacuum the commy and brushes afterwards to remove any dust/sand.

 

[hooveru4089]

Thanks for all the tips!

@hoovercelebrity: If I were to use a lathe, as MPN suggested, I would imagine I could easily use commutator stones, am I wrong?
@vacuumlover: Would 220 grit be good enough, or should I use something finer?