Impact Wrench Troubleshooting & Repair

Impact wrenches, whether cordless or pneumatic, are powerful and versatile tools commonly used in automotive and mechanical work. Proper maintenance and care of your impact wrench can help to keep its performance at its best and extend its service life for many years.

Impact wrench maintenance and care

Impact Wrench Maintenance and Care

Impact wrenches have many moving parts that need attention so that you can make the most of your tool. Here are some tips for the maintenance and care of your impact wrench:

1. Lubricate Regularly

Impact wrenches need proper lubrication to prevent damage and excessive and/or premature wear.


Cordless impact wrenches need less attention than their pneumatic counterparts; however, although they seem to be maintenance-free, this isn’t always the case.
Have you noticed grease coming out from the front of your tool? If so, that grease has to be replenished at some point.

Disassembling your cordless impact wrench may sound scary, but don’t worry; you just have to grease the moving parts, which are pretty easy to access.

Cordless impact wrench maintenance

Apply multi-purpose grease to the anvil, the ball bearing between the anvil and the spindle, the planetary gears, the main gears (located inside the hammer case), and the inside of the hammer case as well.

What is inside a cordless impact wrench

You will also want to lube the motor; just apply some lubricating spray to the casing and the same grease you used for the rest of the parts to the motor’s shaft.

You can watch the video below to get an idea about how it’s done.


There are several ways to keep your pneumatic impact wrench properly lubricated.
These tools have two important mechanisms, the “air motor” and the impact mechanism. Unlike their cordless counterparts, these parts are lubricated separately.

Let’s start with the air motor lubrication:

There are two ways of doing this. The first is as easy as running an inline air tool oil. It’s as easy as installing an inline lubricator in your compressor and filling it with oil, and that’s it; your air tools will always be properly lubricated.

In case you don’t have a two-way compressor, or you don’t have separated air pipelines for other purposes like paint guns or inflating tires, you will have to drop oil inside your impact wrench’s air inlets to keep it clean and well-lubed. It’s important to oil the tool every time you use it if you don’t use it often. If you use the machine all day long, it’s recommended to oil it at least twice a day.

You should apply between 5 to 10 drops of air tool oil, depending on your tool’s specs and the type of oil you use. Then run the tool for a few seconds to ensure that the oil is spread across the tool’s moving parts.

If you are using your tool all day, every day, you should consider installing an inline lubricator.

Lubricating the Hammer Mechanism:

Depending on the tool’s make and model, there are two types of impact mechanisms and lubrication. Check what kind of impact wrench you have before starting.

Grease Impact:

  • Open the tool by removing the hammer case, and you will have access to the impact mechanism.
  • Then remove the anvil, bushing, hammers, hammers’ frame, and the anvil lugs.
  • Clean all the parts with a rug and apply a small coat of regular grease to the anvil, hammers, and the inside of the hammer’s frame.
  • Put the hammers back inside the hammers’ case and, before reassembling it, put a good amount of grease on the anvil, the inside part of the hammer case, the anvil lugs, and the bushing.

And that’s it; repeat this process approximately every 48-60 hours of use.

Oil Bath:

The impact mechanism is covered by machine oil, usually SAE20 or SAE30, but check your tool’s user manual to check what type of lubricant and how much oil you should use.

Applying incorrect oil or under or overfilling your tool may damage it or reduce its lifespan.

To reoil your machine, remove the oil filler’s plug, drain the old oil, and fill it with new oil through the filler plug. Some models require removing the hammer case to drain the old oil. It can be a messy process, so be careful.

The oil change interval of these tools is about three to six months for professional-intensive use and between six months to a year for domestic use.

This is another good video that shows how to lubricate both types of guns.

2. Keep It Clean

Always clean your impact wrench at the end of a hard work day. If you have a pneumatic tool and don’t use inline lubrication, pour a few drops of oil into the intake ducts and make it spin for a few seconds before storing it.

It’s important to remove dirt buildup and water stains that can enter the tool and produce damage and corrosion. Make sure to remove debris and dust, but avoid using abrasives and cleaning solvents that may harm the tool’s housing.

3. Inspect It Regularly

Check for damaged parts every time you disassemble your impact wrench for maintenance. Also, be alert for torque loss clock or anti-clockwise; this may be a signal of damage that will require expert advice.

If you use the tool a lot, consider buying an impact wrench tester. They come in a wide range, from 50 bucks up. You don’t need a sophisticated tester to check your tool’s power output. For simple DIY or light work, I don’t think it’s necessary to buy one.

Also, check for any signs of misalignment or others signs of damage every time you clean your tool; it can be helpful to have your gun repaired before it gets severely damaged.

4. Proper Storage

Always store your tools in a dry and clean enclosed location, away from moisture, dust, and other particles. Besides, always remove the socket before storing the tool.

Common Problems and Troubleshooting Tips

Following are some of the problems with impact wrenches and their repair solutions.

Impact Wrench Not Producing Enough Torque

Below you will find some ideas for cordless and pneumatic tools.

Cordless Impact Wrenches

  • Check Your Batteries: Weak, old batteries can make your wrench lose power. Try charging the battery if you haven’t used your gun for a long time or try using a new battery if that doesn’t work.
  • Electric Motor Problems (Brushed): If your tool is not brushless, the motor brushes may be worn and need to be replaced. This is one of the most common reasons for the failure of brushed machines.

Brushed motors also have a winding made of copper. Winding can get damaged and reduce the motor’s output. Dust can damage the winding and produce a short, burning the motor. This is hard to check at home because most impact wrench motors are sealed units, so you will have to take the machine to a technician.

  • Electric Motor Problems (Brushless): Brushless tools’ motors use bearings to keep the rotor centered inside the housing. Bad bearings usually make a lot of noise before they completely fail, so the mechanism will keep working before they completely fail, causing the tool to lose power.
  • Dirty Trigger: Triggers have a switch that regulates how power reaches the motor. Dirty triggers will prevent current from reaching the motor, which can cause power loss. You can apply contact cleaner to the trigger or open the tool and clean the switch thoroughly.
  • Mechanical Problems: poor lubrication can turn the tool’s moving parts harder to move, which may result in poor torque output.

Pneumatic Impact Wrenches

These tools are much simpler. If you are experiencing a lack of torque from your pneumatic impact wrench:

  • Check the hoses and compressor: pneumatic tools usually lose efficiency due to an insufficient air supply caused by a faulty compressor, air loss in the hoses, connectors, and fittings, condensation, water inside the air pipelines, and other contaminants inside the system.
  • Check the compressor’s air filter: a clogged air filter will prevent enough air pressure from reaching your tool, reducing its performance.
  • Check the impact wrench: if air pressure is not causing the problem, you should check the tool. Usually, a loss of torque is caused by an internal air leak, broken seals, or poor lubrication.

Anvil Often Breaking

  • Extreme weather conditions can strain any tool, and impact wrenches are no exception. Anvils are strong but can weaken when subjected to sudden temperature changes or extremely hot or cold weather.
  • Anvils also break when the impact wrench is overstressed. Make sure that you use a tool that meets your needs. For example, if you use a small cheap tool designed to eventually do some light DIY jobs for professional heavy-duty work all day long, the anvil is one of the first things that will break; it acts like a kind of fuse.
  • Make sure to feed your pneumatic lines with proper oil. If you use flammable alternative oils, they can detonate inside the tool, causing the anvil to break. Never use diesel, kerosene, or fuel oil as a lubricant for your pneumatic wrench.
  • Always use impact sockets. Chrome sockets can damage the anvil, and they can be torn apart by the impact wrench and can cause severe injuries to the tool’s operator and anyone around the area.

Unable to Release Sockets

If a socket is stuck into your impact wrench, you can try some of these solutions before taking your gun to the service.

  • Apply penetrating oil inside the socket and to the outer part of the socket that is attached to the anvil. Wait a few minutes and try again.
  • Put the tool in a firm place, put some rugs below to protect it from damage, and apply little taps to the socket to try to loosen it. It’s the same principle as the impact wrench. Use a small hammer and be careful so that you don’t damage your impact wrench.
  • You can also put the socket in a vise and hit the impact wrench until it breaks loose. Take the necessary precautions to prevent your tool from falling into the floor. It’s a good idea to do it with the help of someone else.

Worn-Out Internal Parts

If you notice that your impact wrench is failing due to worn-out internal parts, there are plenty of repair kits that bring all the necessary parts to repair your tool. It’s important to notice that these kits are not available for all makes and models; that’s why another thing you should consider before buying a new impact wrench is to find out if there are repair kits available and how feasible it is to repair it.

If you can’t find a repair kit for your impact wrench, some generic kits can be adapted to your tool. This may be a good solution if you find a kit that works for your gun, or at least you can find a replacement for the broken parts. Another option is looking for a broken tool that can be used as a parts donor for yours.