I do a mod to bleed all the air the first time you fill it. what happens is there is an air pocket that gets trapped in the motor that would normally go uphill to the radiator in the WRX. In the 818 the water outlet goes down and traps the air. You put in a barb nipple in the water outlet and run it up to the degas tank. If you face the motor from the seating compartment, you drill and tap a 1/8 NPT hole at about 2 O'clock position in the water outlet. Run a line from there to the degas tank and fill as usual. All the air moves up to the degas tank and your overheating problems will be gone.







Brass barb fitting


Hook to the left nipple on the degas tank