# Fix for ShopVac that overheated?



## Labow (Oct 4, 2018)

Not sure if this is the right place to be posting something like this but...

I have a 3HP ShopVac, and the other day I didn't realize that something heavy fell on the hose while i was working and the air flow was significantly reduced, and I think the shop vac overheated. 

Anyone ever have their shopvac overheat? and if so, is there a fix for it? I've already taken it apart and didn't see anything obvious. Would like to not have to buy something new. Thanks for the help.


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## epicfail48 (Mar 27, 2014)

Been a while, but last time i had that happened i found a thermal fuse just before the motor windings. Shorted past the fuse and the vacuum worked. Cant say i recommend it, its a fire risk, but it was the company vacuum anyways


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## GeorgeC (Jul 30, 2008)

Labow said:


> Not sure if this is the right place to be posting something like this but...
> 
> I have a 3HP ShopVac, and the other day I didn't realize that something heavy fell on the hose while i was working and the air flow was significantly reduced, and I think the shop vac overheated.
> 
> Anyone ever have their shopvac overheat? and if so, is there a fix for it? I've already taken it apart and didn't see anything obvious. Would like to not have to buy something new. Thanks for the help.



You "think" the shop vac overheated. Why do you think this? Did it stop working? Air flow could not have been stopped long or you would have noticed that you were not picking anything up. 



On my shop vac I do not think that the flow of air through the vacuum has any cooling interface on the motor. The motor sits above the canister.


George


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## Mark Jones Ozark (Feb 26, 2019)

Labow said:


> Not sure if this is the right place to be posting something like this but...
> 
> I have a 3HP ShopVac, and the other day I didn't realize that something heavy fell on the hose while i was working and the air flow was significantly reduced, and I think the shop vac overheated.
> 
> Anyone ever have their shopvac overheat? and if so, is there a fix for it? I've already taken it apart and didn't see anything obvious. Would like to not have to buy something new. Thanks for the help.


I have had 3 shop vac on off switches go bad. I just wired around them and when I plug the cord in the shop vac works. I did buy a harbor freight foot switch and a remote control switch that makes the tool work great. That could be the trouble as well.


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## Labow (Oct 4, 2018)

Epicfail...I'll try and find that fuse. I'm not much of an electrical guy...what does the fuse look like?

George...I should have said, I'm using the shop vac as part of a dust collection system. I was sanding when this happened, and although it wasn't sucking, the sander just kept pushing dust down the hose. So I was sanding, and then the shopvac cut out and wouldnt turn back on. 

Mark...I'll check the switch, but I don't think that's it.


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## epicfail48 (Mar 27, 2014)

Devil if I can remember, this was about 5 years ago. Little boxy thing is about the best description I can still give


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## Labow (Oct 4, 2018)

Fair enough, thanks. Do you remember if you took the actual motor apart or if it was on the outside?


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## GeorgeC (Jul 30, 2008)

Does not matter if vac was used as originally designed or as part of dust collection. The air being sucked/blown does not pass in/hear/or through the motor to provide cooling.


It may have overheated, but from another cause.


George


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## NoThankyou (Mar 21, 2018)

I would think that in a rarified atmosphere (Hose being blocked) the universal motor would spin faster due to less work load. In all honesty, I don't think that the hose being blocked would over heat the motor. 

Most motors with a thermal cut out switch have a button (usually red) somewhere reasonably accessible. Try looking for that switch. If you press on it and you don't feel as though the switch snapped it was probably already closed.


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## epicfail48 (Mar 27, 2014)

Labow said:


> Fair enough, thanks. Do you remember if you took the actual motor apart or if it was on the outside?


Had to take it apart. Already said it, but to appease George and the safety police again, this is a temporary fix to hold you over until you get a new vac. Also, youre right, some have separate fant for cooling the motor and suction but most shopvacs use airflow generated by the suction to cool the motor. Dont believe it, go plug the air inlet on your vac and run it for 10 minutes, tell me how cool it stays


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## J.C. (Jan 20, 2012)

You put a much greater load on the motor when you restrict the airflow. Some of the more expensive vacs have a bypass valve that opens when airflow from the hose gets restricted but most/all of the cheaper vacs don't have that feature and you can certainly burn one out restricting the airflow for long periods of time.


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## Labow (Oct 4, 2018)

JC, Yes, i think that's exactly what happened. 

Well, i guess I'll go take it apart and see what I can find. Thanks for the help.


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## Pineknot_86 (Feb 19, 2016)

Mine started smoking so I tossed it. It would blow hot air when it ran a long time but never to the point of what I would say overheated.


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## GeorgeC (Jul 30, 2008)

J.C. said:


> You put a much greater load on the motor when you restrict the airflow. Some of the more expensive vacs have a bypass valve that opens when airflow from the hose gets restricted but most/all of the cheaper vacs don't have that feature and you can certainly burn one out restricting the airflow for long periods of time.



WOW!! Those must be some vacuums. Never seen anything like that. Will you please list some (a?) brand names so that I can research.


George


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## epicfail48 (Mar 27, 2014)

GeorgeC said:


> WOW!! Those must be some vacuums. Never seen anything like that. Will you please list some (a?) brand names so that I can research.
> 
> 
> George


1) Shopvac. Again, personally melted one doing this exact thing


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## J.C. (Jan 20, 2012)

GeorgeC said:


> WOW!! Those must be some vacuums. Never seen anything like that. Will you please list some (a?) brand names so that I can research.
> 
> 
> George



The festool CT Sys has a bypass valve.


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## Tool Agnostic (Aug 13, 2017)

GeorgeC said:


> WOW!! Those must be some vacuums. Never seen anything like that. Will you please list some (a?) brand names so that I can research.
> George


My Sears Craftsman 16 gallon wet-dry vac (model: 113.178080) has a bypass valve. 

The bypass valve can be annoying when vacuuming up sawdust from the floor. The wide plastic head at the end of the hose sometimes "sticks" to a flat surface, triggering the bypass valve. You can hear the sound change and the hose stops sucking. You turn it off to reset the valve. Just before the motor is done spinning down, you can hear a large flap thump back into position.


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## GeorgeC (Jul 30, 2008)

Tool Agnostic said:


> My Sears Craftsman 16 gallon wet-dry vac (model: 113.178080) has a bypass valve.
> 
> The bypass valve can be annoying when vacuuming up sawdust from the floor. The wide plastic head at the end of the hose sometimes "sticks" to a flat surface, triggering the bypass valve. You can hear the sound change and the hose stops sucking. You turn it off to reset the valve. Just before the motor is done spinning down, you can hear a large flap thump back into position.



You sure you are not hearing the plastic ball that cuts the vacuum when the vacuum tips over? I have had two of those Craftsman units and neither had a bypass valve.


George


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## GeorgeC (Jul 30, 2008)

epicfail48 said:


> 1) Shopvac. Again, personally melted one doing this exact thing



Now that is a double wow. It melted even though it had the bypass valve. I currently have a 16 gal Shop Vac Brand (after many years of Craftsman)and it has no valve. This one has a so called stainless steel body. Unfortunately that stainless steel rusted through and I have had to patch two holes with aluminum tape.



George


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## Tool Agnostic (Aug 13, 2017)

GeorgeC said:


> You sure you are not hearing the plastic ball that cuts the vacuum when the vacuum tips over? I have had two of those Craftsman units and neither had a bypass valve.
> George


You are probably right. After following this thread, I assumed it was a bypass valve. I was surprised that it would make the list, and I guess that it did not. 

Thanks for the hint.


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## epicfail48 (Mar 27, 2014)

GeorgeC said:


> Now that is a double wow. It melted even though it had the bypass valve. I currently have a 16 gal Shop Vac Brand (after many years of Craftsman)and it has no valve. This one has a so called stainless steel body. Unfortunately that stainless steel rusted through and I have had to patch two holes with aluminum tape.
> 
> 
> 
> George


My apologies, i thought you were asking for examples of vacuums that didnt have any sort of auxiliary airflow over the motor


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## GeorgeC (Jul 30, 2008)

I was asking for examples of those "high end" vacs that had relief valves. Would also be interesting to know of those who have flow over the motor as I have never seen one of those either. That would take some extra plumbing to get the air to the motor.


George


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## NoThankyou (Mar 21, 2018)

GeorgeC said:


> I was asking for examples of those "high end" vacs that had relief valves. Would also be interesting to know of those who have flow over the motor as I have never seen one of those either. That would take some extra plumbing to get the air to the motor.
> 
> 
> George


Isn't the airflow / heat issue the reason for the filter in the tank? I bought two HEPA filters for my two Rigid (HD) shop vacuums. Never even thought about it being a heat related issue. They are close to 20 years old.

BTW - The post brought back a pleasant memory and some math.
One .85 Karat natural Blue Diamond ring rated by GIA as about as good as it gets equals a table saw and other miscellaneous power tools.


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## GeorgeC (Jul 30, 2008)

The filter is to keep the dirt from just blowing out the outflow exit. If it did not have a filter the dirt would just enter the inflow side and exit the outflow side.


George


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