Introduced in 1969, the Chevrolet Blazer first appeared as the K5 Blazer. The S-10 Blazer was introduced in 1983. The S-10 Blazer was a smaller version of the full size Blazer, based on the Chevrolet S-10 chassis and drivetrain. The S-10 Blazer became known solely as the Blazer after the 1996 model year, due to the full size Blazer being renamed the Chevrolet Tahoe. The wiper motor on the 1998 Blazer is mounted through the firewall, onto the wiper transmission. Only those with prior mechanical experience should remove and replace this motor.
Trace a line on the windshield, underneath both wipers. If the wipers are not in the downward rest position, move them to this position manually by pushing the wiper arm downward until it stops. Use a window marker to trace the line beneath the wipers onto the windshield.2
Pry the end caps upward from the lower portion of the wipers near the wiper cowl, with a flat blade screwdriver. Remove the wiper mounting nuts with a 3/8-inch drive ratchet and a deep well socket. Pull the wipers upward to remove them from the wiper mounts.3
Remove the wiper cowl mounting screws with a Philips screwdriver or a Torx bit hand driver. Open the hood to remove the foremost screws from the engine compartment area. Remove the cowl from the lower windshield area completely. Removing the cowl will expose the complete wiper transmission and inner motor attachment.4
Insert a flat blade screwdriver or small pry bar between the wiper transmission arm and the wiper motor. Pull the wiper transmission arm gently from the motor. This is a ball socket joint, so be careful not to bend or break the joint or you will have to replace the entire wiper transmission.5
Remove the wiper motor mounting bolts from the firewall of the truck. Remove the motor horizontally. Remove the O-ring rubber gasket from the firewall, if it does not come off with the motor.6
Install the O-ring rubber gasket onto the new wiper motor. Install the wiper motor onto the firewall of the truck, and tighten the mounting bolts to 35-foot-pounds of torque with a 1/2-inch drive torque wrench and socket.7
Install the wiper transmission arm onto the ball socket from the motor. Use a screwdriver to gently push the arm on if necessary. When the transmission arm is installed, you should have some twisting movement, but you should have no horizontal or vertical play between the arm and the motor. If there is wiggle -- horizontal or vertical play -- replace the wiper transmission arm.8
Install the wiper cowl over the wiper arm mounts. Install and tighten all of the cowl mounting bolts until snug. No torque is needed for these bolts. Set the hood down, but do not latch the hood shut once you have installed the cowl bolts in the engine compartment.9
Install the wiper arms in the exact position they were before removal. Use your traced line on the windshield as a reference point to align the wipers properly. Tighten the wiper mounting nuts until snug.10
Open the hood, and install the wiper motor electrical connector onto the new wiper motor. Turn the ignition key in the Blazer to the "II" or "Accessories" position. Test the new wiper motor. Turn the ignition key to the "Off" position when you are finished testing the wipers.11
Make adjustments to the wipers if they are not properly aligned on the windshield. Remove the nuts and move the wipers as needed. Retest the wipers for proper alignment. Tighten the wiper mounting nuts between 20 and 27 foot-pounds of torque with the torque wrench and socket. Push the wiper end caps into position by hand, only after you have torqued the mounting nuts.