When I swapped out the rear hatch awhile back, the donor's rear wiper was seized, so it forced reusing mine. It'd been quiet for some time, but now has an intermittent noise it makes. Point is, I'm worried it'll seize at some point and I'd like to avoid this. I noticed they used a plastic gear under the case which can't be good for longevity. Anyways, any idea what's actually making the noise? Figure this has to be a common issue. Does something typically loosen over time? Maybe it needs grease?

What kind of noise?

 

The rear wipers get used the least so they often have problems like seized bearings or corrosion.

 

Gears are plastic intentionally, so the arm doesn't jam and bend/break something else, like the rear window. Also plastic gears don't rust, they're lighter, and they're cheaper to make. The motors don't last forever so no point making a bullet-proof drivetrain.

The noise occurs during the arm's movement. It's fairly loud. Would be more of a dry bearing sort of noise as opposed to a grinding noise. The donor's plastic gear was all chewed up, so just not a fan of plastic.

in my experience the area that seizes up is where the shaft goes thru a tube to move the wiper. years of dirt, salt and other debris get down in there and corrode things.

 

If your is still functioning you can still save it - take it apart, clean and grease the shaft & housing tube and reassemble.

 

I pulled the nonfunctioning one out of my 90 wagon once, hoping to get it freed up - the gears were just fine and had plenty of grease, but that shaft was so corroded there was no way it was ever gonna work again. We tried soaking it in pentrating oil and using visegrips to try to move it - I think I finally got it to move about a 1/16th of an inch after a couple of hours of fighting with it - gave up and stuffed it back in the car...

 

generally speaking the gears dont get "chewed up" on thier own - there was probably something that stopped the blade from moving suddenly and that is how the gears were damaged.

Hmm, that sounds like what happened to my original hatch's lock assembly. IT was corroded up like that and wouldn't move and almost looked like it sat at the bottom of the ocean for 50 years with all the calcium deposits caked on it. It's like 11 degrees so gonna have to wait until a tad warmer and I'll investigate. Don't remember seeing anything out of the ordinary though when I transferred the unit to the donor hatch. You are referring to the metal tube that passes through the glass? That gets caked up internally?

yes, exactly!

 

The one on my 90 didnt really look all that bad either when I first pulled it out of the car - but getting deeper into it - ugh! your analogy of looking like it sat at the bottom of the ocean for 50 yrs is dead on!