radiator cap 99 civic hatch.
 

This is the most dumb I've felt with a car issue period. I recently bought a hatch all stock. So was pretty sure im leaking coolant from the rad. Cap. I bought oem 92-2000 civic cap from honda the one thats 41 cm in diameter. According to my research there are 2 basic sizes as to which mine should have this one. When I removed it was the bigger one that looks like a spring under the cap says 1.1 on it which is stock.So I bought a 1.1 replacement from autozone. Checked it after I drove in from work to find it leaking bad from that area now. Any help would be appreciated as getting your ass kicked on a rad cap is ridiculous! The oem honda one part #19045 paa-a01is what should fit and doesn't the bigger one does but wont seal? Thanks for any help in advance.

Is the radiator OEM or aftermarket?

Sometimes after market radiators for your proper year will use the older style cap.

Also the rad could be busted from the top part and make it seem like the cap is leaking.

Pretty sure I got it figured out since its not rocket science. Autozone sold me a new bad cap lol. Exchanging the one at honda today and should be good to go. As for what rad is on the car I believe oem denso jus maybe older civic or...

Funny!
I was having cooling issues a while ago and determined if was the rad. cap.
I stroll into Vato Zone and buy a cap. I get home check/compare it with my old one and realize how much the construction of the cap sucks. It just looks so fucking cheap, but the kicker was that the "warning" sticker was all wrinkled and not in a neat manner like an original Honda rad cap. :crazy:

I have an oem honda cap. Brand new it don't fit my aftermarket radiator so I never got to use it... I dunno where your located but come grab it if you want. .