Mysterious gasket appears in resevoir tank, can you help me to ID it

[mfindigital]

I got a low coolant light warning. When I opened the cap, I saw the gasket you see pictured below perched perfectly on top of my coolant inside the reservoir. The shop that replaced the tank 10 months ago says they have no idea what it is, but they are sure it isn't their fault.

Can anyone help me ID this gasket? I'm assuming AND REALLY HOPING that it's from the Cap. I've been gasket diving on google for hours and haven't found it, it's somewhere between hexagonal and octagonal in shape. I don't know if I drove with it, but I'm assuming this couldn't make it's way through the cooling system, but who knows. Just want to make sure nothing will explode soon, she's finally been ripping without dying and feels like the good ol days again.

[WrathOTM]

Here is a pic of the bottom of the cap, really looks like there is at least two gaskets. Double check your cap, maybe the lower one was never seated correctly so it got pushed off.

[NorthernDancer]

Find a new shop

[mfindigital]

Originally Posted by WrathOTM

Here is a pic of the bottom of the cap, really looks like there is at least two gaskets. Double check your cap, maybe the lower one was never seated correctly so it got pushed off.

Found the issue. The top piece that's holding that top gasket in the photo in the pic is missing on my cap. I'm assuming it's somewhere down in the tank because that piece on mine is missing and clearly looks to have broken. The circled part is what I'm missing, the arrow points to the gasket that just falls off because of the missing part.

The second photo shows my cap, and I think you can see the damage. Just contacted my new guy, now I'm worried there may be some rubber melting somewhere in my cooling system.

[iamroddy]

Thanks for the update.

[WrathOTM]

Ya, was wondering what the deal was with the gasket. How does that happen to the cap though?