800600 - COBB Radiator Cap
Nissan GT-R, Mitsubishi Evo X, Subaru

Congratulations on your purchase of the COBB Tuning Radiator Cap. The following instructions will assist you through your installation process. Please read them first BEFORE beginning the install and familiarize yourself with the steps and tools needed. If you feel that you cannot properly perform this installation, we HIGHLY recommend you take the vehicle to a qualified and experienced automotive technician.

Part List

Radiator

Tools Needed

None (shop towels helpful in case of minor fluid spill)

CAUTION!!! It is recommended to install the COBB Radiator Cap on the radiator itself and not the upper reservoir. The upper reservoir cap is meant to be at a lower pressure compared to the cap on the radiator itself. This cap's lower pressure rating allows it to vent pressure into the overflow hose that then goes into the overflow container. When the car is shutoff and the system cools down, the coolant shrinks, and the negative pressure in the cooling system sucks coolant back into the coolant system from the overflow container. The upper reservoir's cap is responsible for system pressurization as well as ensuring the back and forth movement of coolant from the overflow reservoir. The cap on the radiator is of a higher pressure rating as its job is to maintain the coolant system pressure. If the two caps are of the same value, air can potentially be introduced into the system causing the vehicle to overheat

Removal of Factory Radiator Cap

Locate the stock radiator cap on the radiator.
Push down and twist the cap counterclockwise to remove.

Installation of the COBB Radiator Cap

Push down and twist the COBB Radiator Cap clockwise to seat.
Congratulations on installing your COBB Radiator Cap!
It is highly suggested that the cooling system be properly re-filled and bled after the new COBB Radiator Cap has been installed to ensure that any existing or new air pockets have been eliminated from the system. Please consult factory service manual for proper procedure.