Weird Wiper Issue

[CDL1542]

So I've been working like a madman on my 240z and replaced the wiper motor AND linkage (which I thought was the issue). The thing is this: Before installation, the motor works great and I can even turn the linkages freely by hand without issue. Once installed, the wipers won't move. This isn't the standard "wet glass needed" situation either. Without wipers on, the pegs don't rotate. Figured I'd ask for some help. The connections are all good, wiring is solid and the battery is fully charged. Thanks for the help!!

 

Chris

[djwarner]

May I suggest that you un-mount the wiper mechanism and then connect the wiring. Operate the wiper motor and verify that it wipes on both speeds and parks when you turn them off. With them in the parked position, re-install. Verify they continue to operate without wiper blades and again park. Install the wiper blades in the parked position.

 

My guess is worn motor brushes.

[Zed Head]

That's a sign of a weak motor.  Mine would get stuck occasionally, even after I had it rebuilt.  It Before you take it apart again, you might lift the blades off the windshield (stand them straight up) and try it.  This will be essentially like no wipers but will be minimum effort required.  Might remove the weird factor and replace it with weak.

[CDL1542]

The wipers operate in both speeds and park when on but onces the motor and linkages are installed they do not rotate.

[Zed Head]

Without wipers on, the pegs don't rotate.

Sorry, I got lost in the description and didn't see this part.  Seems like a binding issue.  Sometimes people install the linkage with the motor shaft in the wrong position.  I think that it might also be possible to get the linkage installed in the wrong orientation.

 

Pretty good drawings in the FSM.  Have you confirmed proper installation or did you put it back the way you found it?

 

Also, you might try running the wipers through their motion with them off the motor shaft.  If you can't do it by hand, the motor probably can't either.

[Zed Head]

The wipers operate in both speeds and park when on but onces the motor and linkages are installed they do not rotate.

I don't really understand this part either.  How can you confirm that the wipers operate if the linkage isn't installed?  What moves the wipers?

[Zed Head]

In sum - not sure what you're describing.

[CDL1542]

Zed head. When I pull the linkage and the motor out and leave it hooked up to the wiring harness, the motor operates smoothly at both high and low speeds. It does cycle back to the original (park position). When the linkage and the motor are installed, the motor will not rotate the linkage properly. I'm not sure what is causing it to seize up. The linkage additionally operates smoothly when not installed in the car as well.

[Zed Head]

Do you mean that you unbolt the motor and let it drop a bit?  Or that you pull everything out and reassemble it?  Just trying to figure out if you have everything in the same orientation when it works and when it doesn't.

 

I remember how difficult it was on my 76 to get all of those parts in and out of the holes in the cowl.  What if you leave the bolts holding the motor loose?  

 

I do know that the Z motors will definitely stop if there's too much force required to move things.  Unlike my 1995 Pathfinder which will bull its way through all obstacles once the wipe command has been given. So it seems like a simple binding issue.  

[Zed Head]

There was a guy on another forum who had installed the linkage at the motor 180 degrees off.  His wipers worked but they tried to park on the hood.  Maybe you're seeing the wipers move and park but what you're seeing out of the cowl area won't work once installed.

 

Anyway, here's a drawing of how things are supposed to be.

[Chickenman]

^ That's what I was thinking. You can install the short arm that is attached to the wiper motor shaft 180 degrees out. If that is done you can still attach the main linkage to the arm, but it will be in the wrong position to actually MOVE the linkage and it will lock up solid. Guess how I know.... 

Edited September 26, 2015 by Chickenman

[CDL1542]

This sounds like the problem.... I'll have to give it a shot! Thanks!