Attachment for interior ceiling (AC Grill)

[AreVee]

My AC grill(not sure what to call the interior plastic cover) was loose (making a good rattle while driving). It looks like a previous owner replaced a couple of the screws with larger ones, but those were had come looses (and I couldn't tighten them). What's a good way to attach things to the ceiling? It looks like 1/8'' plywood, and maybe there's nothing behind it at that point? I'm not really sure if I'll need to take the grill on and off a lot, which might kind of change the best fastener to use...
Maybe plastic drywall anchors (those probably aren't great for taking on and off, and they might be better with a thicker wall?)
Toggle bolts would let me get it on tight, but won't be great if I need to take it off.
The "bolt holes" in the picture would be great, but I'm not sure how they'll work with the thin wood.

Any experiences would be appreciated. Thanks!

First pic is where the cover was.
Second pic is (what I assume is) an original screw and hole.
Third pic is a new (larger) screw and hole.
Fourth pic is one idea to fix it, but maybe not a great idea

[Old-Biscuit]

DO a search for 'Extra Short Hollow Wall Anchors'

Metal expanding holder for thin paneling




OR use some Command Strips to attach grille to ceiling

We used Command Strips to hang pictures on our RV walls back in 2007
FTnd for 7 yrs and nothing ever fell off the wall....some pictures were large and heavy.
Pitures still hanging today.

[Persistent]

The second picture with the flat head screw will probably not work (you said it doesn't). The smooth section of the shank will never tighten in the thin panel. Threads must go all the way to the head. It depends on how thick the cover is.

In any case long screws are unlikely to work better than short screws. Larger diameter screws may solve the problem, but you may have to drill the cover holes out a little.

The best way to hold something to thin ply is to use many small short screws. So if you can put more holes in the cover and add screws, that may permanently solve the problem.

Pan head screws may work better than flat head, but the shape of the hole in the cover will determine head type.

The brass inserts you show require thick material. They are unlikely to work well.

The hollow wall anchors may work if the anchor is rated for thin ply. They work well in 1/2 inch drywall.

[AreVee]

Thanks for the suggestions. It turn out on one side there was a little space to get in above the ceiling - not enough for hand but enough that I used a toggle bolt, and if I ever need to take it out I could get a magnet in there to grab the toggle part as I take it out. On the other side I used a plastic expanding drywall anchor. Seems to be working so far.

[bigb56]

On mine I put some toothpicks covered with wood glue into the holes then when dry the screws gripped again. I suspect they got stripped by someone using a screw gun on them, they only go into luan and Styrofoam on mine.