Okay, so I finally get the relay in so that I can let the wipers park themselves. They park halfway up the the windshield
So I pull off the blades to reseat them at the appropriate spot, and when the wipers are turned on, the first place they want to go is down
I can't figure out how to adjust them! The hood is off, and everything is exposed, and as I watch them cycle, I am lost as to how to set them so that they park properly, and not scratch the paint off the cowl!
Anyone have any thoughts?

 

never had this problem. Did you swap the motor at some time? Nice color pal.

 

Can't really help.
But did you put wipers on slow wipe or just nudge it the get 1 wipe cycle?
Think I've gotten wipers to park 1/2 up on the down stroke if I release the command wand at the wrong time.

Adjust the wiper to rest position when motor drives it to the lowest point on the windscreen.
Flip the wipers up off the glass so it is in the clean windshield position.
Then put it in slow wipe to see roughly the range of blade arm travel. That should give a rough idea of where the blades wants to go and not bash the hood cowl paint.


Or strap a squeegee guy to the hood so he/she can clear the windshield when it's raining or misty.

 

Ed...........with the engine running (so the elec system as at peak) switch the wipers full on then off. See where they sit.

They do tend to park wrongly 'sometimes'.

 

Linderpat ... I have had that problem. And there was nothing I could do. No matter what I did, the system parked itself in the wrong place. I even replaced the entire mechanical system with brand new. I did not replace the relay, maybe I should have tried that. The system parks itself too high or too low, no matter how I adjust it. If I go overboard on the high side, it jumps back up, and if I go the other way, it parks way too low and misses much of the windshield top left.

 

Thanks guys, but it's none of the above - I have played around with them for over an hour, in every possible configuration. The park position is squarely in the middle of the windshield.
Also Earnest, be very careful about running them with the wiper blade up off the glass - I put a nice gouge in the top of my fender yesterday doing just that. With the blade down, the wiper blades themselves stop the mechanism form going further into the cowl, but you do hear the motor straining to push the blades down into the cowl nevertheless. With the blades up, there is no resistance and the bracket at the bottom of the blade just keeps going until you see/hear the painful gouging of nicely painted aluminum fender.

There has to be a fix to this, I'm just not getting it.

The wiper motor was replaced when I bought the car, but the relay wasn't used, because of this parking problem (it hadn't ben working when I bought the car either). I could just simply pull the relay again and manually park the blades, but after all of the other work I've done to this car, I hate the fact of a loose end on something that seems like it should be very fixable, but presents a geomatry problem. UUGH!

 

I haven't been inside a 928 wiper motor but I have been in several others BMW, Fiat... In all previous cases and I would asume in the 928 as well there is a contact ring on the one of te gears that continues to supply a current path to the wiper motor when not in the parked position. My guess is there are two possible causes for the problem.

1) if the motor was previously disassembled who ever put it back together clocked the gear with the contact in the wrong position so the contact ring breaks its connection at the wrong position believing it has reached the desired part location.

If this first case is the issue the motor will need to be dissassembled and re-clocked to achieve the correct parking location.

2) when the wiper motor was originally assembled there is grease on the gears and contact ring. over time this grease tends to harden and increase in viscosity. when this occurs it creates a barrier that the contact rides on and looses contact with the slip ring. then this happens the connection is broken to early and the motor parks before it has reached the fully stowed position.

If it is the second scenario you will need to disassemble the motor usa a good electrical parts cleaner to clean the contac and contact ring, re-lubricate it using dielectric grease and reassemble it.

 

But if that's the case, then why would it always park in the position it does now (halfway up the windshield)? Wouldn't what you describe cause random parking each time the wipers are turned off?
Thanks in advance...

 

DO THIS FIRST remove the arms first so you dont do any more damage.
What was the last thing you fixed??
There is a control wheel in the wiper motor where the gears are it may have gotten dirty , also check the relay open it and inspect the contacts

 

Hi Ed,
I had the same problem after changing out a wiper motor. The problem is the indexing of the splines on the motor where they drive the linkage. If it is one or two splines out you will either have the down first syndrome or the park mid screen.
I solved my problem by :
1.first removing the wiper blades from the linkage spindles
2. Run the wiper system so it self parks
3. Loosen the central nut on the motor spindle and pry the linkage up slightly so that the linkage will slip on the motor shaft.
4. Turn the wiper spindles slightly one way or the other (you may need to re fit the wiper blade to do this)
5. re tighten the motor spindle and try the cycle again (without wiper blades fitted)
You are looking for an immediate rotation of the wiper spindles in a single direction. If you don't get this you need to do 3-5 again until the spindles rotate immediately in one direction. You are trying to eliminate any over centering of the linkages relative to the drive spindle.
Once you have achieved this, run the cycle once more then fit the wiper blades to their spindles in the park position. You should then be good to go.

 

Wiper arms were removed immediately. I am using a small wire fitted onto the stem to act as a pointer now. The relay is fine - in fact, I have 2 and the problem is the same with both. This problem has existed for as long as I've owned the car - tried to fix a couple of years ago, and just gave up. Now I'm determined.
The wiper motor was replaced, and that didn't help. There is a solution here, we just don't know what it is. I can't help but to think it's a geomatry thing. If anyone has their cowl cover off and can post pictures of what the mechanism looks like when the wipers are in the parked position, that might help. I'm about to pull the motor out per 76FJ55's suggestion, but I'm not optimistic about it, since the same problem existed with the prior motor, and the new one didn't fix it.

 

Whoa Jay - This might be the home run I am klooking for!

 

Jay may have the answer i hope so

 

Jay - you solved it!!! Million thanks - it worked. A little tedious with back and forth adjustments, and I had to remove the cowl piece in order to get the clearance I needed, but nothing has been scratched or broke, and I finally have the full use of my wipers, including the intermittants

 

I believe Jay may be correct. on the systems I worked on previously the arm was integral with the motor. If the motor is attached to the arm through a splined connection I would guess it is clocked wrong at that location. tis will give the same effect as I was indicating in scenario 1 only the motor doesn't have to be disassembled to re-clocked, as it can be done at he motor shaft connection.