Fan switch washer for plastic end tank

[supercity]

Hi

I have bought a new aftermarket radiator and I am concerned about how the fan switch seats and seals. It has a brass incert but the old steel washer actually locks up against the plastic, not the metal incert like it did on the old rad. Is there a better type of washer to use to seal against plastic?

 

[kschachn]

Wow, I just noticed the same thing last weekend on my BMW. It would have made more sense to me if the washer would have sealed against the brass insert in the radiator, but it does not. It seals against the plastic boss. My washer was copper though, are you sure yours is not aluminum?

 

[supercity]

It could be alloy but it's old and crusty so hard to say. I'll buy a new one at least so it is malleable. Maybe copper is better,

 

[kschachn]

Well it would be rusty if it was steel.

BTW mine sealed perfectly against the plastic, it just was weird as no other components on the car seal that way. But I kept and eye on it and it is dry as a bone. I actually had four of the copper washers to compare; the original one (probably OEM), a new OEM washer, an aftermarket washer, and one that came with the new sensor. All four sealed against the plastic.

What kind of car is this?