Dumb ? What is this part?
 

Small reservoir by the battery. It has fallen out and looks to be pretty corroded from the old battery. http://forums.pelicanparts.com/uploa...1521737927.jpg

windshield washer pump and/or headlight washer pump

Yep.

Water/meth injection pump!

Good for hot track days. ;)

Thanks!

Now I just have to figure out how to shove the rubber grommets back in their holes. Despite the corrosion, it still seems to work fine.

Windshield squirtie motor. +1

I don't have the headlight washer on my 81 but on a 944 I worked on the headlight washer was on the bottom of the fluid reservoir. It was way more robust than the windshield motor.

Just did that recently.
I cleaned them then lubed them up with SilGlide a silicone lube then pushed and wiggled they went right in.

jw

Pull the grommets out from the side of the washer pump bracket. Look closely and you'll see the bracket is slotted to allow the grommets to be inserted. Push the loose/free grommets into the chassis wall (the long end is used for pulling the grommet into place) and then reinstall the pump to the grommets by sliding the bracket slots into the grommets

Looks corroded, these things wear out and are cheap to replace...

The trick on the grommets is carefully pry them sideways out of the pump bracket with a small screwdriver and don't pull them out of the front panel. The slots in the pump bracket are C shaped which makes it tough to get them back in place, so use a dremel or small disc cutter and make the slots U shaped. The grommets slip in easily and the pump ain't going nowhere.

The way the pump looks, I may assume it does not work anymore(?), so I'd not install it, as retreiving it when finding out its dead, it will rip the grommets.
If it does work, I'd refurbish/clean it (inside/outside) before reinstalling.

thanks for asking. was trying to figure out what that was in my car also. :)