How to Tighten a Windshield Wiper Retaining Nut

Everyone has been driving in the snow and had slush and ice build up on their windshield wiper blade. Normally this is a quick easy fix by reaching out the window, grabbing the wiper and knocking the ice off against the windshield. However occasionally doing this can cause the wiper retaining nut to come loose and make the drivers side wiper not usable.

Part 1 of 2: Tightening the Retaining Nut

1.Turn the windshield wiper switch off and allow the blades to drop into the rest position. Turn the vehicle ignition switch off and remove the key.

Place a rubber mat, cardboard or some other piece of material in the work area and position it to protect the glass and paint finish in case a tool slips.

2.Pry the plastic cap open covering the nut. Verify that the arm position is still correct and using a small flat screwdriver, pry the plastic cap covering the nut at the base of the arm from the recessed nut well. The plastic cap may have a small slot to assist in inserting the screwdriver.

3.Tighten the nut. Once removed and having determined that the wiper arm is in the correct location on the drive shaft, select a 3/8" drive socket that fits the nut recessed in the nut well.

    Be certain that the socket is an exact fit as some are metric and some are SAE. Place the socket (and short extension if needed onto the ratchet handle and insert the socket over the nut. Gently attempt to tighten the nut. 

   If the nut is already very tight, stop this process. If it turns easily, continue to tighten until it gets snug and then go about 1/8 of a turn more to secure the nut.If the nut was already very tight, you will need to loosen the retaining nut and remove the wiper arm for inspection. If you discover that the wiper drive shaft hole in the wiper arm has a reamed out appearance, it will be necessary to purchase a new wiper arm and install it.

4.Test the wipers. Turn the ignition key on, turn the wipers on and test the travel of the arm for proper operation. If the arm slips, you will need to replace it.

Part 2 of 2: Replacing the Arm

1.Clean the drive shaft splines with an old toothbrush and some WD-40. This will remove trapped metal and dirt from the shaft splines.

  Wipe the splines completely dry after cleaning.

2.Examine the new arm. See if it has matching splines that will mate with the shaft. 

If it does, carefully fit the splines together matching them, being sure that the arm is positioned correctly on the windshield.

Gently tap the arm down onto the shaft and clean the threads for the retaining nut.

3.Install the retaining nut by hand. Ensure that the nut turns freely and is not cross-threaded. If it turns easily, continue to tighten until it gets snug and then go about 1/8 of a turn more to secure the nut.

4.Turn the ignition key on, turn the wipers on and test the travel of the arm for proper operation.

   If the wiper arms clear each other, move smoothly and do not travel into the molding at the edge of the windshield, turn off the wiper switch and ignition key.

5.Using a small plastic mallet or similar tool, tap the plastic cap back down into the nut well, aligning any grooves or tool prying slots to their original positions.