Wipers don't work

[Bijan]

Hi!

Beside the question regarding the intermittent mode in a different thread
I have a general problem with my wipers and I am really running out
of ideas why it doesn't work!

When I turn on the continuous mode (the intermittent doesn't work at all as you know)
the wipers start moving and then get stuck after some seconds.

This means that:

a) the engine's power is too low to move the wipers
or
b) that the mechanical resistance in the whole assembly
is too high for the engine.

I have done the following already:

1.) Disassembled, cleaned and greased the whole mechanism
including the flexible connection shaft. Everything moves now
without high resistance, so should be fine.

2.) Changed the wiper engine with a used one. This made
the wipers work for my first try. When I re adjusted the wipers
today the same problem as before occurred.

When I turn on the wipers without the wiper arms on the
windscreen it works absolutely fine! It also works when I lift
the wipers a little when they got stuck. This leads to
the assumption that the wiper arms are not correct (pressure on the
wind screen is too high) but this would be very strange as the whole
car is completely original.

I could cut the springs in the arms a little but I would like
to hear some other opinions before I do this. Does anybody
have a picture of original 2.4 litre wiper arms?

I have to say that I am getting very frustrated about this

Thanks for you help! Cheers

Bijan

[Tobi]

Maybe some contact resistance? How's the voltage diectly at the motor?

[Bijan]

Hi Tobi,

I have already measured the voltage on the cables that
feed the engine: It is a bit lower than the battery voltage
but I thought it is normal, isn't it??

I can't say off the top of my head how much lower it was,
but I think it was about 0.3 V lower than the value measured
on the battery directly.

However, I will clean the contacts tomorrow and measure
again.

By the way: the problem with the wipers also occurs when the engine
is running...

Cheers
Bijan

[Tobi]

Try to supply the motor directly from the battery to see if there is a difference. If the wipers still not work, it's not an electrical issue.

[Guzzi]

If swapping the motors doesn't fix the problem I'd suggest it's likely to be mechanical or adjustment rather than electrical, give that the problem reoccurred once the arms were adjusted. Too much spring pressure could cause the spindles to bind but it's unlikely. Was the screen wet when you tried them?

Peter

[Bijan]

Thanks for your suggestions!

I've tried the following today:

- Direct power supply from the battery --> No positive impact!
- Swapped the engine again with a third engine which I have
borrowed from another parts supplier. --> No positive impact!
- Cleaning of all electric contacts --> Voltage on the engine is now only 0.02 V lower than
measured directly on the battery but in the end wipers still don't work.
- bent the wiper arms a little so that the friction on the windscreen is lower. --> Again no positive effect!

I conclude that it must be a mechanical problem. Maybe it is the angle of the wiper axis
in relation to the windscreen OR the plastic cogs in the two worm gears that are worn.

The worm gears turn without resistance but I can hear a slight cracking sound some times. This would be my
very last idea to solve the problem. The 124 Spider wiper assembly looks like it uses pretty much the
same mechanism in the worm gears. I'll try to find out if the known dealers can supply spares...

I am talking about this part:

http://www.midwest-bayless.com/p-18723-9924293.aspx

http://www.holtmann-niedergerke.de/shop ... 39&pageNr=

Cheers

Bijan

[fdus172]

On the mechanical side of things going wrong.... I have a 2.0 coupe - so it may be different on your 2.4.... My experience was similar, everything seemed fine until I put the blades on... With the blades off, it worked fine - but looking closely with the blades off, it was clear that the attachment posts were operating backward. That was making the blades try to wipe the hood, and was immediately binding. Careful assembly closely following the diagram in the parts manual, and then making sure the the posts rotated correctly solved the problem.

Rick Wohleber
Portland Or

[Bijan]

Thanks for the suggestion Rick, but the attachment posts move in the right direction,
I've checked this already.

I didn't know that there is a documentation about the wiper assembly, so
I am going to check this today...

BTW: The screen is always wet when I try it.

Cheers Bijan

[Guzzi]

I think you're on the right track with the gears, the 'cracking' is probably the gears slipping, if they're worn it won't take much to take them out of mesh

[Bijan]

Jackpot: I've just spoken to T. Niedergerke who has two
NOS (!!) cogs on stock!

Hopefully I will get them by the weekend otherwise
I will have to wait until Christmas to try it again
since I work far away from home...

I could imagine that worn cogs cause high friction once
they're under load, even when then seem to be OK without
load.

Cheers

Bijan