How To Oil An Impact Wrench? Comprehensive Guide

Air impact wrenches are very handy tools both for home maintenance tasks and for your workshop. Tight, rusted bolts are very tedious to work upon. An air impact wrench loosens them with ease and gives you the result in seconds. Most impact guns come oiled from the manufacturer when you buy it. Since there are rotating parts in your wrench, they need to lubricated properly to give you a smooth performance. Learn how to oil impact wrench using this step by step tutorial.

There are two things that need to be oiled in your air impact wrench:

1. The air motor: The vane motor in your air impact wrench needs to be oiled using an air tool oil available from most air impact gun manufacturers.
2. The rotating hammer: The hammer that drives the force from the air motor to the anvil, needs to be oiled using a motor oil of appropriate weight. Castrol SAE 30 motor oil can suit this purpose.

As the impact wrench gets old, the oil evaporates due to the heat and also gets contaminated with small metal chips, resulting in your air impact wrench not giving the optimum performance. The air impact wrench in such a scenario makes absurd clicking sounds when you use it and also does not give a smooth performance.

1. An old air impact wrench to clean and oil
2. Motor oil of weight 30, Castrol SAE 30 oil has ben used for this tutorial
3. Air tool oil for oiling the air motor
4. Petrol or any other spirit for cleaning the parts
5. Align key, Punch tool and a hammer
6. Compressed air supply

Step 1: Remove Rubber Jacket

Take the air impact wrench and remove its rubber jacket if it has any.

Step 2: Remove Back Plate

Remove the plate at the back by removing the nuts with a 4mm align key. Keep the gasket at the bottom of the plate carefully.

Step 3: Remove Alignment Rod

Take note of the alignment rod present, remove it and keep it properly.

Step 4: Remove back Bearing

Put a slight tap on the anvil using a punch tool and hammer to remove the back bearing.

Step 5: Remove Air Motor and Vanes

Remove the air motor that becomes visible after the back bearing is removed. The air motor has vanes in its grooves which cause the motor actions. The vanes need to be cleaned after dis-assembly.

Step 6: Remove Air Motor Housing & Front Bearing

Tap the anvil from the front to remove the air motor casing and the front bearings subsequently.

Step 7: Remove Hammer Assembly & Anvil

When the full air side of the equipment is removed, now its time to remove the hammer assembly. Push the anvil from the front to remove the hammer along with the anvil.

Step 8: Separate the Hammer and Anvil

There is a round gasket that holds the hammer and the anvil together. Remove this gasket carefully with a screwdriver. Do to tear it in the process.

Step 9: Clean Up Internal Parts

Now you can see all the internal parts of the air impact wrench and also the body of the air impact wrench tool. Clean them properly with petrol or any other spirit to remove any solidified oil or metal chips that may be present.

Step 10: Assemble Them Back

Put them all back together by going in the reverse direction of the process mentioned above

a. Attach the anvil with the hammer with the help of the gasket.

b. Put the hammer assembly inside the air impact wrench body followed by the front bearing and then the air motor casing.

c. Align the air motor properly and put it inside the air motor casing. Put some air tool oil on the vanes to make them smooth.

d. Put back the back bearing and align them together using the align rod.

e. Put the gasket on and then the back plate after they are properly aligned. Tighten the 4mm nuts to fix the back plate in place.

Note: You can find the full video of the assembly at the bottom of this article.

Now it is time to oil the air impact wrench.

You need to oil two parts of the air impact wrench separately as mentioned in the introduction to this article. To lubricate the hammer mechanism, you need to use a motor oil having weight 30. You need to lubricate the air motor using a proper air tool oil from your manufacturer.

First we lubricate the hammer mechanism and then the air motor.

At the side of the wrench you will find an oil port. The steps of how to oil air tools is given below.

Step 1: Remove the Oil Plug Nut

Remove the oil plug nut present over the oil port using a 4mm align key.

Step 2: Put Motor Oil

Insert about 1 ounce (approx 29ml) of 30 weight motor oil inside the oil port to lubricate the air impact wrench hammer mechanism. You can use a syringe for this purpose.

Step 3: Put Air Tool Oil

Insert about 6-7 drops of air tool oil inside the air port of the impact wrench to lubricate the air motor and vanes of the wrench.

Step 4: Run the Tool for around 30 Seconds

Now it is time to put in the air supply and rev up your tool for around 30 seconds to 1 minute. This will cause the lub oils to be properly distributed in the hammer and air assembly.

Step 5: Drain the Excess Oil

Open up the oil plug again and drain the excess oil onto a container

Step 6: Put on the Rubber Jacket

Put on the rubber jacked over the air impact wrench as was before and your tool is as good as new now!

Now that you know the full process of cleaning and oiling your air impact wrench, you can quickly follow the steps at home making your tool as good as new again!

You can find the full video of the process here.

I hope this guide was useful and would like to know your difficulties if you face any with the process.

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