i thought the koyo rad was a direct drop in

 

You must have AIR in your system or something. I have no shrod on mine and it runs cool.

 

the koyo is a drop in replacement and i do have my coolent level sensor in. so would that rule out the air in the system? and would it make sence that it's my thermostat? i don't know how old it is, possiably original.

 

well replace it and find out, make sure to use an OEM thermostat, they are the best.

 

perhaps your radiator is alot closer to your mechanical fan on the zuki and theres noplace else for fresh air to come in?



my #1 suspect is the shroud, although there can be so many other problems, maybe the fan clutch isnt engaging, thermostat stuck, air in system... water pump problem.



why was the radiator getting replaced?

 

The waterpump won't pump air, so if there is air in the system (and it wouldn't take much) it would be trapped in the system, not in the raditor where the sensor is. I would power flush the system and make sure the thermostat is working (drop it in a pot of boiling water) It should open fully.



They other thing you can do is have a mechinanic check the coolant for the presence of Combustion, IE Coolant leak. It doesn't take much of a leak to bring up the temp, and it could happen without you losing coolant. (That happened to me on my honda). I know it's not a rotary.. but it might be worth checking.