shop vac overheating? Outlet cap the culprit?

[Jay Yoder]

I purchased a shop vac on closeout from the Blue BORG a few years ago and just got it out of box to use it last week. After about 2-3 hours of non-continuous use, it started to smell burnt. The longest it ran continuously was 10-15 minutes. This particular model came with an outlet "diffuser" that threads over the outlet connection. Do you all leave this on? If I leave it off it will blow dust everywhere! I also had another vac that burned up/quit working after little use and I had left this diffuser on as well. I began wondering if this cuts down on airflow and cooling to the motor? I have a third shop vac (yes I am an addict) that I bought 6 years ago and have used heavy with no issues but I took the cap off and replaced with muffler I got at the BORG. Is this cap an issue for anyone else?

[Myk Rian]

This particular model came with an outlet "diffuser" that threads over the outlet connection. Do you all leave this on? If I leave it off it will blow dust everywhere!

Do you have the filter on correctly? Check that. It might blow drywall dust, but it shouldn't anything else.

[Jay Yoder]

Myk, the filter is on correctly. It doesn't bypass dust, but when I take the cap off the motor exhaust, it is so strong and concentrated it blows paper and dust and whatever else is in its path everywhere.

[Myk Rian]

Sweep the floor.

[Jason Roehl]

What have you sucked up with your shop vac? If you're vacuuming very fine particles, the filter will clog quickly, which will reduce the airflow through the impeller, which will then overspeed and overheat (that's why the pitch of the noise goes up when you block the hose inlet). For any sanding dust, be it drywall, wood or others, you should use a disposable bag in addition to the filter (I get the ones rated for drywall dust).

[John K Jordan]

For any sanding dust, be it drywall, wood or others, you should use a disposable bag in addition to the filter

I agree with the comment that fine particles will clog the filter and reduce the airflow and cause overheating.

I use a bag over the filter which makes a huge difference. I don't use a disposable bag, I simply slip a burlap bag over the paper filter and hold it in place with a removable nylon wire tie. The burlap keeps the paper filter from clogging and I get a much higher suction and much longer times between cleaning the filter. When the vac is full or I notice a reduced suction, I shake the bag out, knock and blow the dust out of the filter with compressed air (outside, of course!) and all is like new with no disposable costs.

JKJ

[glenn bradley]

I've run a Ridgid vac with the diffuser on for 13 years and it is still going strong. The vac will get hot if run for 10 - 15 minutes; hot enough to be unpleasant to lay your hand on the motor area but, not so hot as to burn you. How is your electrical? Could the vac be on an inadequate circuit that makes it heat up more than normal?

[Bill Orbine]

Shop vac from Lowe's doesn't have a good reputation with me. Burned two up and in garbage they go. Rigid from HD seems dependable after 7-8 years of service and it's still running. I use these on field.

[David Malicky]

The diffuser shouldn't be much of a restriction. Like Jason said, if the motor speeds up when the diffuser is on, it is restricting. Else, that's not the problem.
Agreed that ShopVac brand is not as reliable as Ridgid.

[Jim Finn]

I have killed three shop vacuums before giving up on using them with my scroll saw. I ran them longer than 15 minutes because I am often at my scroll saw for hours. I now just blow the dust to one side with a hair dryer mounted to my floor lamp beside my saw.

[Mike Henderson]

The diffuser shouldn't be much of a restriction. Like Jason said, if the motor speeds up when the diffuser is on, it is restricting. Else, that's not the problem.
Agreed that ShopVac brand is not as reliable as Ridgid.

+1 I had one of those Blue Borg vacs. I never had a problem with it overheating but it was LOUD. I got a Ridgid from HD and have been satisfied.

The cooling air for the motor is separate from the vac air. If the motor runs at a higher speed, it should get more cooling air. It *should* be designed not to burn up even if the suction is blocked or the filter is clogged. I would consider it poor design if it did - things happen and the vac shouldn't die because of a restriction.

Mike

[Jay Yoder]

What have you sucked up with your shop vac? If you're vacuuming very fine particles, the filter will clog quickly, which will reduce the airflow through the impeller, which will then overspeed and overheat (that's why the pitch of the noise goes up when you block the hose inlet). For any sanding dust, be it drywall, wood or others, you should use a disposable bag in addition to the filter (I get the ones rated for drywall dust).

.

Jason, All I have sucked up is saw dust and some larger chunks of wood. I have the pleated filter it came with installed as well as a drywall dust bag that you mention. Interestingly enough, the noise dropped lower instead of the noise that I have heard when it gets full.

[Jay Yoder]

Just to update situation, I called shop-vac and they have a new power head on the way. In discussions with the tech, I was advised that the cap might slightly restrict flow but that should not have burned up the motor. She also advised to not run it for more than 30 minutes consecutive. Then it needs cool down period. I took apart the burned power head and oiled the bushings but did not feel any drag. When I checked the armature (???) It seems that where the brushes were contacting the rotor, there appeared to be drag marks left on the rotor. It also had a trail of soot looking substance on only one half of the rotor. I wonder if that is the problem? Regardless after running for 5 minutes the smell came back and continued to get progressively worse.

[Tom M King]

Don't know if this is part of the problem, but there is another filter up under the motor housing. There are a few screws to take the cover off the motor. Take that apart, and clean it out.

Nice of them to send another motor.

[Jay Yoder]

Tom, I have never heard of another filter. where is it again?

The replacement motor came today (talk about excellent customer service). It installed quickly and was back up and running in 5 minutes. The vac seems to be smoother and after 5 minutes or so I didn't smell the burning I had before. We shall see how long it lasts, but for now we are back up and running. I looked at the vac and it appears to have 2 intake nostrils on the front (hose side) of the unit. Thanks all for your input, next time I may try Rigid. Merry Christmas early to all! Stay safe!