Best to replace bad windshield washer pump

Hey there, time traveller!
This article was published 19/09/2003 (8059 days ago), so information in it may no longer be current.

QUESTION — The windshield washer pump on my 1987 GMC half-ton keeps spraying all the time the wipers are turned on. The only way I can shut the washers off is to disconnect the top wire connector at the wiper motor. Then I don’t have any washers at all. How can I fix it?

ANSWER — There are two ways of fixing your problem. One is to repair the existing washer pump. The other is to install an aftermarket electric washer pump. I would lean towards installing an aftermarket pump. It is probably the cheapest repair, easiest to do, and in my opinion gives superior performance.

Mount the electric washer pump at a point below the washer reservoir. Electric pumps don’t suck fluid up as well as they can push, so mount the pump low. Cut the existing washer hose from the reservoir and connect the end from the reservoir to the inlet of the pump. The other end of the hose should go on the pump outlet.

Next, disconnect the three hoses from the factory washer pump at the wiper motor and connect them with a plastic tee. The plastic tee will be available at most auto parts stores. Finally, run two wires from the two wire connectors at the washer motor (the ones that you have been disconnecting) and connect them to the electric washer pump. Whenever you push the wash button on the dashboard, the electric pump will run. If no fluid is being sprayed onto the windshield, then the wires may need to be reversed to get the pump turning the correct way.

To repair the original pump, it must be removed from the motor. Carefully disconnect the two electrical plugs at the wiper motor and snap off the plastic cover. If you are not careful with the large electrical connector, you may damage the electronic circuit board and it will need replacement.

Remove the screws holding the metal washer pump base to the wiper motor and turn it over. You will find a round disc about the diameter of your little finger mounted on a flat plunger rod. This round disc will be worn on one side and is the cause of your washers not turning off. Turn the disc carefully with pliers about a half turn and coat it with grease to prevent more wear. Sometimes the disc can’t be turned and the whole washer assembly must be replaced.

Next, reinstall the washer pump base to the wiper motor, making sure the pin on the wiper motor sits on the outside edge of the plastic cam on the back side of the washer pump. Reconnect the electrical wires and operate the washer. Watch the plastic cog wheel on the outside of the washer pump assembly and replace it if it stops turning before the wipers turn off. The repair isn’t simple if you aren’t familiar with these pumps, but parts are available.

QUESTION — The heater/air-conditioning fan in my 1990 Ford Tempo operates only in high speed. When I switch to other speeds, the fan stops blowing. What could be wrong?

ANSWER — This is fairly simple. While the problem could be a bad connection at the fan switch or a bad fan switch, it is unlikely. I suspect there is a burnt thermal limiter fuse in the heater resistor block.

The thermal limiter fuse protects the resistors from overheating due to high electrical current flow. It cannot be replaced separately; replace the complete resistor block assembly. This is fairly simple: Remove the glove box, and on the front of the heater housing you will see an electrical plug going into it. Unplug the connector, remove the two screws holding the resistor block, and pull it out of the housing. The block is not much larger than a deck of cards. Installation is done in reverse order.

Sometimes these fuses just fail, but if a second one burns out, then the heater motor is likely drawing too much electrical current and also requires replacement. You can test the heater fan by operating it directly with a jumper wire with a 20-amp inline fuse in it. If the fuse blows, then replace the heater motor.

Jim Kerr is an experienced mechanic, instructor of automotive technology and freelance journalist. You can e-mail questions to Jim at the address below.

kerr.jim@sk.sympatico.ca