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Will Not Power On ¶ 

The Dremel 4000 does not respond when the power is switched on.

Switch Lever Does Not Engage ¶ 

While there could be several reasons for the tool to not power on, a common and simple problem is to check that the switch lever is properly engaging the electronic assembly. A guide on how to replace the electrical assembly can be found here. Dremel 4000 Electrical Assembly Replacement

Faulty Power Cord ¶ 

In order to determine if the power cord is faulty, you will need to disconnect it from the electronic assembly and connect it to a voltmeter. A guide to explain how to replace the power cord can be found here. Dremel 4000 Power Cord Replacement

Faulty Electronic Assembly ¶ 

If the tool will not power on, and the switch lever and power cord have been checked for integrity, then the electronic assembly must be replaced. While there are multiple parts within the electronic assembly, the entire assembly is delivered as one piece and must be replaced in its entirety. Dremel 4000 Electrical Assembly Replacement

Tool Will Not Vary Speed ¶ 

The Dremel 4000 will power up, but will not vary in speed.

Faulty Electronic Assembly ¶ 

If the tool will power on, but remains fixed at one speed despite adjusting the dial, then the electronic assembly must be replaced. While there are multiple parts within the electronic assembly, the entire assembly is delivered as one piece and must be replaced in its entirety. Dremel 4000 Electrical Assembly Replacement

Shaft Will Not Lock ¶ 

The Dremel 4000 shaft will not remain locked when installing/removing bits.

Faulty Shaft Lock Button ¶ 

If the shaft rotates even when the blue shaft lock is pressed, the button will need to be replaced. A guide to explain how this is done can be found here. Dremel 4000 Shaft Lock Pin Replacement

Tool Makes a Squealing or Whistling Sound ¶ 

The Dremel 4000 makes a whistling or squealing sound when running.

Faulty Bearing Assembly ¶ 

If the rotary tool is making unusual sounds when running, and those sounds intensify when a load is applied, you may have faulty bearings. For this tool, the entire armature and bearing assembly is replaced at once. A guide to demonstrate how this is done can be found here. Dremel 4000 Bearing Assembly Replacement

Tool Is Overheating ¶ 

The Dremel 4000 is overheating under standard operating conditions.

Ventilation Slots are Covered ¶ 

Check the four vents on the tool to ensure that they are not covered or otherwise blocked. If the vents are not covered up, but overheating persists, it is possible that dust has accumulated inside the case and must be cleaned out. A guide on opening the casing can be found here. Dremel 4000 Back Case Replacement

Faulty Bearing Assembly ¶ 

If the Dremel is overheating, yet the vents are clear, check that the fan on the bearing assembly is functioning. If not, the bearing assembly will need to be replaced. For this tool, the entire armature and bearing assembly is replaced at once. A guide to demonstrate how this is done can be found here. Dremel 4000 Bearing Assembly Replacement

15 Comments

my dremel 4000 make noise and the temperature fusible (110 ºc) got burned, is a brand new dremel 4000 .

the rotation is not continued is like little jumps, maybe it`s a electronic speed control prblem ??

claudioman2009 - Reply

I had this issue as well. Fixed it by removing one side of the case and blowing out the back end of the "dial" potentiometer with compressed air. It could also be the brush contacts need to be tightened slightly.

Chris Barth -

changed the fusible, and the rotation is not smooth and make noise again and the fusible gets burned again. the Dremel is brand new and clean. worked fine for some hours.

claudioman2009 - Reply

My dremel4000 was working great but I tried this with a 15mm ply and the 561 bit to make a hole. I kept the dremel running for a long time and it got some goose bumps kind of bubble on the rubber side and stopped working. What would be the problem

Arun George - Reply

The electrical assembly does not necessarily need replacing if the tool does not start when switching it on. The switch design is not very robust. The blue plastic on/off button operates a little microswitch just under the variable speed adjuster. If the blue plastic is not pressing firmly on the microswitch then it can fail to turn on. I just took mine apart and refitted everything and it worked. If it fails again then I will glue a little packing piece on the blue plastic to ensure that everything presses firmly together. That ought to fix it.

David Payne - Reply

Ive been disappointed with my 4000 series Dremel. I returned one and then its replacement stopped working. Like David, I also narrowed the problem down to the micro switch not closing properly from the blue slider distorting/wearing down.. It may seem this switch is wimpy for the tool but since the tool is FET driven there is very little current flowing through the switch.

Chris Barth - Reply

I bought a Dremel 4000 on January 28th of this year (2017), just 21 days ago, but I used it for the first time up to a week after purchasing it to remove rust from various accessories of my Dremel 395, from that very first moment I noticed an excessive heating in the Dremel 4000, at the point where the accessories are installed, I estimate that the temperature would be between 54 and 60 degrees Celsius, excessively hot. After checking details such as not obstructing the ventilation holes and checking the free rotation of the rotor without noises or obstructions, and see that everything was fine, I took the Dremel 4000 to the service center of my town where after an "inspection" Of the tool, the qualified technician stated that he had not found anything abnormal in the tool. I asked to have it run in front of me, and after only 5 minutes and without work load, the tool had an excessive temperature that was perceived through the plastic armor and at the tip, the temperature was too high to touch.

faith851 - Reply

In spite of this demonstration of anomaly the authorized service personnel justified with many reasons, some nonsense, the high temperature of the tool, explaining that as the armature did not touch with the field and the bearings did not make any noise, the tool could not be wrong, meaning that they could not validate the warranty or repair the tool.

I retired to my home somewhat disappointed and began to look for information related to this problem of overheating of the Dremel 4000 in the web. In addition to this site, I found many others where this problem with the Dremel 4000 was discussed (including Youtube).

As I do not know if Dremel will validate the warranty and will repair the tool I decided to review it myself, and here is what I found:

faith851 - Reply

The tool is not misaligned, that is, the armature does not stick in any way with the field, as because of friction, high temperature could be generated. The design of the plastic body is not bad nor comes poorly molded factory which could cause an increase in temperature due to poor ventilation. Finally the brushes and rotor were clean, as intermittent contact between brush and rotor can cause an increase in the temperature in the system.

As all of these factors were correct there was only one factor that could cause high temperature in the tool and these were the bearings. So I carefully extracted the armature assembly and bearings and made a simple test: I took the armature through the bearing of one end and letting it hang by holding it only from the bearing then I turned it,

faith851 - Reply

when I took the armature by the bearing that is on the side the brushe´s side, the armature spun free as for 4-5 seconds and stopped gently, but when I took the armor by the bearing that is next to the fan and I turned it, this turned only 2 or 3 TURNS and stopped abruptly. There is no doubt, the damage is in the bearing that is next to the fan.

So I proceeded to remove the seals from the bearing to see what the problem might be, when I removed the seals I saw the problem, what should be the lubricating grease was completely solidified as if it had become solid plastic, this did not obstruct the turning Of the bearing but yes it stopped the free rotation of the steel balls and obviously causes a severe friction which causes excessive temperature in the tool.

faith851 - Reply

I have photos I took of the armor of the Dremel 4000, I do not know if I can share them here, but whoever wants to see them can send me a message to me.

I have photos I took of the armor of the Dremel 4000, I do not know if I can share them here, but whoever wants to see them can send me a message to me.

I have photos I took of the armor of the Dremel 4000, I do not know if I can share them here, but whoever wants to see them can send me a message to me.

I have photos I took of the armor of the Dremel 4000, I do not know if I can share them here, but whoever wants to see them can send me a message to me.

faith851 - Reply

I have photos I took of the armor of the Dremel 4000, I do not know if I can share them here, but whoever wants to see them can send me a message to me.

faith851 - Reply

I have been through 4 dremels, 3 4000 models and 1 3000 model. All off them would short out , no power, hand jigsaw no pover, 2 hand wands just spin and no power either. What the heck!!! I want someone to answer, I want a sales rep to replace all your broken equipment. This is ridiculous, I have been a Dremel tool lover since 96, as an manicurist I depended on its reliability, and I still do.

Yesmin Whitehead - Reply

i just got mine last week, i think all is well, after some tests, started getting additional accessories for my Dremel 4000, twas manufactured November 2016, i noticed the spot where you access your carbon brush ? you cant screw it out ! and i got me some carbon brushes ordered already ...... my Dremel 4000 with manufacturing date November 2016 with a "611" number underneath the date, you cannot access carbon brushes from the out side.....

jonathan roquim - Reply

i happened to see in youtube a guy disassembling his Dremel 4000 and you can unscrew carbon brush hatch from the outside, not having to open it up???????

jonathan roquim - Reply

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