Replaced the F250's wiper motor

Ever since I got it, my 1992 F250 has had a bad wiper motor. The symptom, which can be caused by several different kinds of faults, is that it didn't "park". That is to say, the switch turned the wiper motor on and off, regardless of setting. High speed always worked, but park never did. I proved that the motor was the problem by taking off the cover and cleaning the contacts, and having it work for a short time. Rather than fight corrosion and continually shave switch contacts, I decided to drop the forty bucks retail on a new window motor.

However, the truck has never been a daily driver, and in the winter I mostly use it to pick up firewood. There are indications that this will be a heavy winter, so I thought I might want to use the truck more now that I've let go of the Subaru (which has since been totaled, but it may have saved the driver's life as he walked away after a multiple rollover which was not his fault) and my Ford is the only thing I've got with four wheel drive. It's a big heavy brick with wide, self-cleaning tires, so it's pretty much the opposite of ideal for driving in the snow, but my car is rear wheel drive and has an open differential, and no ABS. The Ford at least has one-channel rear ABS.

The job itself is relatively simple, but my truck is lifted four inches and sits on 35s for another inch of lift, and the truck is pretty big to begin with, so I had to run back and forth with my stepstool a lot, and I'm two meters tall. These instructions apply to the 1992 model year. I do not accept any liability whether you follow these instructions or not. Read and understand all instructions before continuing. Use common sense in case I got a step out of order, or forgot something. Now, on with our show...

The first step is removal of the wiper arms. If they are pulled away from the vehicle, a screwdriver can easily be used to pull out a small stop which will keep them that way. They can then be pulled off of the shaft. You don't need to mark anything, because they'll simply be installed in a parked position. I think both arms are the same, and both sides take an 18" wiper blade. This is a good time to replace your wiper blades too, since you're messing with the system. If you have sap on your windshield, you can remove it by using a straight razor blade in a scraper, only in the cutting direction. Never drag the razor blade backwards; you'll dull the blade and scratch your windshield. Wash it with soapy water first to keep the blade sharp, make it glide easily, and give you a visual record of your progress. I razor bladed my entire windshield and found a couple of small chips I hadn't noticed before.

About a dozen screws (#2 philips) come out of the rubber hood sealing strip and the metal cover over the cowl area, and the antenna is removed (pry cover with slotted screwdriver, #2 philips, pull the plug firmly out of the bottom) from the cowl panel. Put masking tape on the leading edge and top of the cowl and the trailing edge of the hood — I have recently discovered wide poly masking tape which is inexpensive and easy to use for this sort of thing.1 The tape will protect paint on the cowl and the hood during removal. You could mark and remove the hood instead, but that's best done by two people and I was working alone.

With the protective tape applied, you can open the hood (and finish applying the tape) and then pull the cowl panel forward, out from under the trim. Mask off the lower part of the windshield trim, then push the cowl panel back against the firewall, but let it slip over the window trim. This may require a bit of back-and-forth to get right. Then close the hood fully. You should be able to lift the cowl panel up and out, pulling the 1/4 inch plastic line out of the rubber tee under the windshield wash nozzle on the driver's side. You may have to bend the outer/lower tabs of the cowl panel away from the firewall before closing the hood so that it will come out.

Now open the hood again, and remove the shield from over the wiper motor (#2 philips) and then remove the wiper motor carrier from the firewall (10mm socket with 9-12" extension on 3/8" ratchet) to make it easier to get at the clip that holds on the linkages. This sheet metal clip can be replaced with a C-clip if lost, but it's actually hard to lose it in the middle of the cowl area. Pull it away from the shaft and slide it off; gently twist a screwdriver in the upper (away from the motor) part of the clip if you need help. The linkages will slide off the shaft on the end of the arm on the motor. They can only be installed in the proper order; the shaft is thicker near the arm.

I removed the wiper motor screws and the wiper motor arm retaining screw with a 5/16" socket. The arm should be placed in a vise for removal of the retaining screw. You don't need to attach the arm to the new motor in the vise, because you're not going to torque it down that hard; just hold the arm and only the arm while you put it in. The spec is only 5-7 ft-lb for all of these screws.

Installation, as you might imagine, is the reverse. The slightly-longer screws are for the clips that hold the A/C lines, and the painted ones go through the cowl. If the cowl panel has never been removed before, there will probably be a lot of dirt and other crud underneath, which I brushed away with a hard, natural-bristled brush after removing all that is removed. I also pressure-washed the cowl panel and the motor shield panel, because foam which was used in the cowl area had turned into something similar to floral foam but with less structural integrity. Much of this went down into the cowl, but it will wash out over time and the drains can be poked from below, e.g. with tie wire or with a swamp cooler reamer.

When I got my truck the washer motor was disconnected and the washer tubing was missing. I replaced the motor some time ago with a cheap part from O'Reilly's (Trico, maybe) and I replaced the tubing with some clear 1/4 inch stuff I had lying around. Before, pressing the wash button on the end of the stalk resulted in the wipers never stopping, because the circuit has no timer backup and it wants to wipe the windshield three times before stopping. Now, it results in the windshield being washed, and intermittent wipers work fine as well, albeit louder than any I've ever heard before.

  • 1. The poly masking tape also makes a nice tape for securing parts to one another for shipping, like when you buy a printer and unpack it to find strips of tape holding the trays closed and such.