Need help with windshield wiper repair

[Hill Bullock]

My windshield wipers (ww) cut out on me driving in the rain last Feb going to the Annual TCC gathering in Austin. After it had been drizzling a while, they stopped working. Perfect! Even though we weren't getting wet (on the highway), we couldn't see! Anyway, I checked the fuse, and sure enough, it was blown. I stopped at a gas station, bought some more fuses, but ever time I started the ww again, they would go for maybe a second and then stop; the fuse would be blown again.

A few folks suggested it might be a water induced short, which would go away when things dried out. Well, last night I replaced the fuse and tried to fire them up...nothing. I went to remove the motor unit and noticed one of the 3 leads looked like it might have been off already. So I plugged it back in and tried it again. The ww tried to move, but were at the bottom of their travel (at the bottom of the windshield), so they could not...but the fuse was not blown. Hmmm. I forced them up a little and tried again..they tried to work but got stuck again. The fuse still wasn't blown though. I forced them higher and turned them on...they twitched and stopped. Blown fuse. Tried again...blown fuse.

1) How do you adjust the ww, in terms of their height with respect to the windshield. Forcing them can't be a good thing.

2) This doesn't seem to be water related now, does it? Any hints from the behavior what might be going on? If forcing the arms has placed the mechanical "drive train" in a way which over stresses the motor, would this cause the fuse to blow like I am seeing?

FYI, the motor is a Lucas (oh no!) and it drives the wipers via a coiled wire, sort of like the kind used for clearing out a clogged drain.

Any advice or info would be appreciated.

Thanks

[Bob Putnam]

Only three leads? A single or two speed motor?

The two-speed wiper motors that I am familiar with use a cam-driven switch behind the big internal gear. When you shut the wipers off, as the motor comes around, the switch grounds out the windings in the motor. If the dash switch isn't doing the right stuff (and it's fairly complex), you could end up with a dead short.

Unfortunately I know nothing of the one-speed motors, although I might have an early MG manual somewhere around.

[Dan Heck]

I think you've identified the problem:

".....FYI, the motor is a Lucas (oh no!)...."

Nevertheless, I'm sure there are many here who can offer more informed advice than I can, but if yours is an old junkyard Lucas wiper unit like mine [$15; whatta deal!], perhaps the grease in the motor's gearbox or the tube may just be dried out and stiff so that it loads the motor and blows the fuse. Your speculation that a bind in the cable drive or the 2 gearboxes on the wiper shafts might be loading the motor sounds reasonable as well. I took mine all apart and cleaned & greased it up well when I salvaged it-the construction and assembly of the mechanism is simple and straightforward, so I wouldn't hesitate to dig into it & check things out.

Dan

[Hill Bullock]

It is a two speed motor...ON and OFF. Seriously, though, I only have a 2 position switch, so it may be a 3 speed, but I have no way to activate the other speed with my existing switch.

[petek]

I've got some pictures and a schematic at my web site ... you'll have to hunt for them. ( http://www.birch.net/~petek/cobra )

Since the fuse blew out the motor is probably safe. I'm guessing that when the motor stalled the current increased, blowing the fuse.

The roto-rooter wire thing doesn't spin, it goes in and out; pulled and pushed by a cam in the motor drive head. It's a funky arrangement, so typically English (Hey, my grandmother was English, so it's ok for me to pick on the English.)

One thing you might try ... pull the wipers off of the wiper stalks. There is a tiny wire bale that holds the wipers onto the stalks (at least on my Cobra). With the wipers off put a new fuse in and check to see if the motor runs ok.

If the motor runs freely, turn everything off and put the wipers back onto the stalks ... the drive end of the stalks are knurled, you should be able to position the wipers so that they won't bind anymore. The wiper arms themselves (if they are like the ones on my Cobra) can be adjusted for length ... but the angle is adjusted by the positioning of the arm on the drive stalk.

If the fuse blows with the wiper arms off I'd guess that the drive head has a problem. Take the motor and drive head out of the car, remove the bolts that hold the cover plate onto the drive head and take a look, fix what ever is broke. I had to do this on my other project car ( http://www.birch.net/~petek/m6gt ).

I hope this helps,
petek

[Bob Putnam]

Does the wire connection (socket) look like the one on petek's page (the schematic about 2/3 of the way down)?

[Hill Bullock]

I am very UNelectrically inclined, but that is what it looks like. I don't remember the wire colors, though (I am at work now). I will print out that page...

Also, I tried to pull the wiper arm off the stalks, but it wasn't obvious how that was done. There was one nut which locked the assembly down to the body, but nothing obvious for removing the arm. But I think we all have the same Finish Line setup, so I would think it works the same as yours...

[Bob Putnam]

The "normal" wiper arm is a press fit (via a small internal spring) onto the spindle. Use a flat screwdriver to pry the round section off, opposite the arm - VERY CAREFULLY...

[Hill Bullock]

I will give it a try.

Thanks!

[Jack21]

Lucas 2 speed wiper motor has 3 wires coming from it, hi, lo, and ground; all connected to park switch. Disconnect all 3 wiresfrom the park switch. Connect ground direct to chassis ground. Connect hi & lo to dash switch and manually jog the switch to park the blades. Park switch is piece of sh*t, and am redesigning it. The park switch is what's blowing your fuses.

[Bob Putnam]

Jack,

Not all Lucas 2-speeds use three wires - in fact I've never seen one like that. We use what I think is an earlier style with five wires.

[jwoodard]

Here's a link to a picture of the wiring schematic for the Lucas setup.

http://home.flash.net/~jwoodard/Image389.jpg

Jim

[Jack21]

Thanks Bob,

The factory wiring on this Lucas 3 wire motor had the ground wire going through the park switch. Every revolution of the motor caused a dead short and a popped fuse. The wiper switch is hot in off and activates the park function. I put a diode in the circuit to keep it from feeding back through the ignition. Shortly after installation, the park switch broke so I had to disconnect it.

Am working on a park switch that uses a standard industrial limit switch to park the blades.

[Hill Bullock]

After messing with it for a few hours, just when I was ready to start pulling the whole dang assmebly out, I stumbled on the problem. The wires which run from the motor to the big connector were getting pinched by the mounting bracket and were shorting out! It had nothing to do with the rain or the wire binding! (sigh) So I put on some electrical tape, used some spare weather stripping (to create a buffer), and reinstalled. Works like a champ.

Thanks to everyone for all the suggestions. I put them all to use until I stumbled on the real culprit.

[dougp726]

I have the Lucas 2 speed wiper that uses a cable drive. I have owned an MGA and a TR-6 which have made me paranoid about anything with the Lucas name. The wipers work but the cables often slip in the gearbox. Any ideas as to the problem.

dougp726

[133bus]

Do you mean the gears in the motor unit or the wheel boxes at the wiper.If the drive wire is skipping by the drive on the wheel box ...that can be adjusted by bending the bottom up toward the wheel a small amount or the side cover with the two screws can be bent closer to the wire or both...the wheel may be worn by now so check that first
steve