Wiper Woes

[retinadoc]

My new to me '76 40 seems to have a strange gremlin in the wipers. They only have one speed which I assume is slow. They work for 5-10 minutes, then I start to hear a thump with each stroke, then they slow down, finally they stop and die. If I let the car sit for a while they are miraculously resurrected and the cycle begins again.

I did replace the blades immediately when I got the truck, as the old ones did not do the job, but that is the only variable I changed. Probably the PO never changed them for a reason. It is snowing today so this is sort of bummer, as I finally figured out the transfer case mechanism.

Any help from the collective would be greatly appreciated. I assume electrical but I am just guessing.

 

[thebigredrocker]

It’s probably just a bad ground.

A quick temporary fix might be, attach a gator clip to the wiper switch and a clean firewall bolt. If that doesn’t work you may need to clean up harness connection, possibly pull your switch apart for cleaning.

Recent thread on wiper connections
Wiper Motor Tech

 

[thebigredrocker]

At some point you may also need to clean the wiper linkage sockets and add some new grease. You may have old dried out dirty grease that gets extra sticky when cold.

 

[spotcruiser]

Just a couple of things I'll toss in here.

Don't expect the wipers to run well against a dry windshield. They just don't do well with too much drag. If you're testing them, wet the windshield. This isn't aimed at you, it's just something that I've noticed over the years.

These are old trucks and, depending on where they've spent all/most of their time, the wiper motor can have a lot of run time on it. I had the wiper motor of my '76 trail truck fail on me during a blinding rain on a busy highway on the way to a wheeling trip some years back. That's no fun. It was running fine when I left home, then slowed and began to get intermittent. I bailed on the trip and limped home to deal with the wiper motor. When I opened the motor, I found that the brushes were worn out. As you might expect for the rainy Northwest, the high-speed and common brushes were the shorter of the three brushes, with the high-speed brush barely there. The low-speed brush was at just about the end of it's pigtail. I looked around on-line and found tool brushes of a size that could easily be sanded down to the correct size and with a pigtail sufficient for making the electrical connection. I replaced the brushes and the motor has worked properly since then. I've posted about this, as have several other people. If you search, you'll find the threads.

There are other ways to deal with the wiper motor issues, as you'll find in search, but I personally find the brush replacement to be the easiest. I've repaired a couple of other motors since the original issue.

 

[B y r o n]

Since the truck is new to you it's also possible that everything needs to be taken apart, cleaned, lubed and put back together. If the grease/lube is dry or none existent then it's possible things are just seizing to a halt because things are getting warm/hot.