Here's the issue the car over heats when its not in motion, it does this randomly, its happened after going for a fun drive or just puttering along in regular traffic. When it does try to overheat the coolant fills the overflow tank and doesn't suck back into the cooling system. The radiator stays full but the top part of the system where the second rad cap is needs to be topped up when this happens. It ran for about a year and a half without issue other than a misfire issue that has come and gone. In the last 6 months I've had it looked at by a dealership 3 times without any success of solving the issue, they want to pull the heads to see if there is something wrong inside they can't diagnose.
I have replaced the thermostat, both rad caps and the coolant. The coolant that came out when the t-stat was replaced was as blue as it is new from the jug, no crud, gunk or grit came out of the rad when the system drained. There is no coolant in the oil or vice versa, it starts and drives just fine with out any other problems just this overheating issue that nobody can point a firm solution at. All oil changes are done with Amsoil filters and signature series oil at about 5000km intervals. Oil is sent off for analysis and the reports come back good with little fluctuation in the tests from one to the other.
I had all the below work done between the fall of 2015 and spring 2016 now have 30000km on the car since the rebuild and tune:
-Techworks Engineering engine build- new crank, rods, pistons, bearings, 5 angle valve job, springs and retainers, valves, valve guides, lifter buckets, oil pump upgrade, new timing set, plugs, multi layer steel head gaskets and EGR delete
-Airboy tuning Dyno tune after break in was completed for husky 94 fuel
-Killer B windage tray and oil pickup tube
-OS Giken Grand Touring twin plate clutch + aluminum flywheel
-Kartboy short throw shifter
-Whiteline swaybars and endlinks and steering bushing kit
-2015+ STi steering rack upgrade
-DBA 4000 rotors front and rear with Endless racing MX72 pads all around
-Stainless steel brake lines all around
-Gramlight 57DR 18x9.5 +40 wheels all around with 265/35zr18 BFG sport comp 2 tires
-Tomei equal length header with up pipe ceramic coated
-Cobb catted Down pipe, Cold air intake with box, turbo heat shield and v2 Accessport
-Perrin Turbo inlet tube
Looking for anyone who's had a similar issue to resolve and what you had to do to solve it. Considering the engine was fully built and is rated for far more than the factory turbo and fuel system can throw at it I'd be very surprised if the heads need to be done already. I'm not ruling that out as a possible problem at this point, just hoping there is something else to look into first to resolve this problem. Sorry for the long post just figured it would be better to give as much info relating to the problem as I can. Thank you all and have a good one.