I can't recall if the temp sensor has a rubber seal, but here's an
image of a rad I took apart

https://picasaweb.google.com/musomuso/19WBXRadiatorOpenedUp#slideshow/5377715609621259522

IIRC, there's a rubber seal between each tank and core and this is
what I see in my pic above.

Maybe that's what you found?

Neil.

On Sat, Jun 29, 2013 at 10:30 AM, David J <mdhiker@yahoo.com> wrote:

> Checking why my radiator fan wasn't coming on, so removed and tested the radiator temp switch (the large module that screws into the radiator and gets power to the fan when the temp is high enough).  Inside the radiator was what seemed to be a rubber band, sticking into that side channel, as if it extended from the coils.  It stuck out far enough out so I could easily hook my finger in and pull.  It snapped, and I removed a 1.5" chunk of (seemingly) rubber.

-- 
Neil n

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