I blew a piston on my 13B!!
 

haha I'm just kidding....but I do have a question....I was prepping my car for installation of my new radiator (whenever it gets here :( ) and I removed 2 what is probably sensors... to me... on the very top and another on the bottom right...anyone who has installed a koyo or changed out an s4 radiator in general....can you tell me what those are? if you know what i am talking about?

Coolant level sensor and temp switch.

thanks alot....so should I replace those? or keep them and then transfer them over?

whats a piston? i would replace them and keep the old ones for spares bcs they do wear out if they are good but if u wanted to as long as they still work u can tranfer them over loctite makes a good thead sealer u might wanna check it out and its rated for high heat and presure to

thanks I'll look into that

IIRC, the bottom one is for the AWS.

i thought the bottom one's are for automatic trans only? i just installed my koyo today and i didn't find any sensor at the bottom of my stock radiator, of course i have a 5 speed. :P

The temp switch (bottom) is for the emission controls and not really important. The level sensor (top) is very important.

I've been running with the bottom one disconnected for years now.