2002 Toyota Corolla. Changed out the coolant on our friends car to find a beat up square rubber o-ring loose in the radiator neck. Photo below with it resting on the radiator. Please advise if this is cause for concern ? Otherwise the car runs OK with no leaks.

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  • 1
    Seems like it doesn't belong there. Where exactly was it found? Was it pressed by the cap or was it floating inside the radiator, immersed in coolant? In the first case it might be some strange attempt to "fix" something, e.g. relieve pressure inside the cooling system by not letting the cap seals to seat properly. And in the second (again, just a guess) it might be that some seal in the system has fallen apart and travelled up to the neck.
    – max
    Oct 30 '19 at 6:54
  • thanks @max it was just under the water in the neck, kind of folded up. agree that it seems wrong we will keep an eye on the cooling system.
    – ajayel
    Oct 30 '19 at 17:53
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    Possibly somebody was repairing something, "lost" that seal or gasket in the cooling system and couldn't fish it out, and over time it's found its way into the top of the radiator. It could be almost anything, unless you can find it on an exploded parts drawing of the engine somewhere.
    – alephzero
    Oct 30 '19 at 19:10
  • @alephzero i have studied the parts diagrams it's not clear where this came from. we'll just have to monitor the system and check for problems.
    – ajayel
    Oct 30 '19 at 19:56
  • I found something similar to this today, but it was a broken o ring, like a circle not a square, i was curious if some kinda seal could have broken? I just had my fuel pump replaced but this is in my radiator.. Jan 26 at 22:02

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