2003 Pontiac Montana, wipers frozen in snow, idiot (me) left them on,
thinking
they'd "break free".

Wipers now park in a vertical position. Doesn't affect the operation
otherwise.
Thinking this is simply a "re-align the wipers on the crank" thing,
adjusted them
as per manuals -- put them in pulse mode, wait until they park, then
pull the motor
crank and realign it. Nope -- when the park after a pulse, they're
fine. When they're
off, they're vertical.

Now I see that the motor crank has a switch on it, and a cam, and a
slot and pin,
and a spring all around it. Basically, like most things in cars, is
another "simple"
thing that has had years of thought put into it. Probably to try to
survive abuse by
idiots like myself, and to recover from most things that would down the
Space Shuttle.

Can this cam mechanism be "reset" or recovered in some way? Is this a
designed
"fail-soft" behavior? What does all this crap in the cam do? I'm
really curious.

Mark

gmark wrote:
What has probably happened is that the cam or gear responsible for
tripping the "I'm parked" switch has been forcefully wrenched from its
proper position on its shaft. It is very unlikely you can "fix" this
because the gear/cam usually shatters (where it counts...not
necessarily where you can see it).

But...

If you want to try... find the switch contacts, disassemble the
gear/cam from the rest of the machinery. Consider filling the broken
cavity into which the shaft used to fit with epoxy (2-part, slow dry)
and then force the gear/cam back onto the shaft but now in the correct
position. Don't forget to wash the gear/cam in several changes of
solvent to remove all the lubricants that may be floating around in the
cavity. Let the epoxy dry AT LEAST 48 hours before touching it.

The REAL solution is to visit a "recyclling" yard and get a wiper motor
that works...or a dealer and buy a new one (possibly more expensive
than buying another vehicle of the same vintage.)

You can probably get the crank arm assembly from a dealer or parts supplier.
I had to replace one once on a Cavalier.


"webpa" <webpa (AT) aol (DOT) com> wrote

Woody wrote:
Well, folks, here's a strange part. I have the crank cam assembly in
my hand now, and I'm looking at what appears to be the electrical
contact
part, and nothing seems to be broken. What I'm looking at is a main
crank
consisting of a flat piece with the knob at one end (for the wiper arm
that's
under the hood, which extends to the other wiper), sandwiched between a
cam on one side (with a notch that a spring loaded pin pops into when
the
cam rotates and locks), and another sort of cam on the other side with
a
slot in it. This last flat cam has the electrical contact piece on it,
and is
attached to that center, main flat crank piece against a tiny,
slinky-sort of
spring like a string wrapped around the separating disk.

All that complication being said, it SEEMS to me like this assembly is
meant
to allow the crank to move around separately when the wipers are stuck
somehow,
so the motor doesn't labor too much and burn out. Extra stress on one
of the
wiper arms (the rods under the hood, that is, not the blades above)
causes that
pin to be pulled out of the slot, and the cam on the top to turn free.
I assume
the spring is meant to exert friction to prevent the pin and cam from
rotating
in normal, non-stuck operation.

Bottom line -- it LOOKS like whatever has happened, the cam is back in
a
"normal" position (pin's back in the slot, cam's rotated back to where
it was),
and there's no damage. I just don't see how these three pieces of flat
metal
are in anything other than normal relative positions. If they're not,
of course,
I'd be able to rotate whatever it is back to normal.

I've got a FEELING that this clever mechanism is intended to absorb
that abuse
and allow a mechanic (or the driver) to simply force the mechanism back
into
a "normal" orientation.

This has me MUCHO INTRIGUED. And if it's not so, I just don't see the
reason
for all this monkey-motion hardware. If it IS so, wow. VERRRY clever.
And,
considering how much stress wipers can be under in various weather
conditions,
quite reasonable (especially considering that wipers are a major, often
ignored,
critical safety feature).

All we need is a GM engineer to spill the beans :-)

Mark

The gears box is screwed up, replace the motor, WBMA


mike

"gmark" <gmark (AT) svs (DOT) com> wrote

I'm really curious about this -- is this a common occurrence? And how
the heck does
this all work? (as you can see, I don't just want to fix it, I want to
know more about it).
There's a sensor/switch on the cam and plate that I can see. I assume,
then, that
there's another switch inside the motor, and that the motor itself has
gears (which is
what you're saying).

Also, pardon my ignorance, but what's "WBMA" mean?

Thanks!

Mark


Mike Hunter wrote:

My Montana wipers park up if there is snow down around the arms. Once
*all* this snow is cleared away, they park correctly.

gmark wrote:

Generally, one needs to disassemble the motor, IF it is serviceable and the
gears have not been damaged, then realign the gears. If not, you will need
to replace the motor. The cam simply moves the wiper arms from the 'park'
position to the 'run' position, and vis versa, when turned to the 'On/Off'
or 'Interval/Off' position.


mike


"Pat Coghlan" <news@coghl'an.ca> wrote

gmark wrote:

Did you adjust the wipers at their connection to the shafts or adjust
the crank where it attaches to the motor's shaft?

The motor will park at the same position relative to its gearbox output
shaft. If the primary crank at this pont slips, adjusting the wipers on
their shafts won't help.

--
Paul Hovnanian mailto:Paul (AT) Hovnanian (DOT) com
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