I put another new radiator in last week. I drove around for 4 days with no spirited driving. After letting the car cool down for a few hours there was no coolant loss vai the rad or overflow tank. On day 5 I drove around for 2 hours and had a little fun. The next morning I noticed that there was a small amount of coolant lost in the overflow. I've pressured tested the system and found no leaks. The head gasket is fine. I've been fighting this for a long time. I'm wondering if the heater core has a small leak but my passenger side is never wet. I can always smell coolant but never see the leaks anywhere. Any thoughts?

 

there is coolant running to ur Throttle Body to warm it up when its cold so it doesnt stick. Might wanna check that its by ur TB (obviously) Other than that, make sure ur not leaking from ur thermostat housing and that ur hoses are fine. If its a small leak, it might not make ur floor wet, but u might wanna check it anyways.

 

I once had a very small hole in the line between the TB and the head. It would only open at higher rpm (+3000). It would shoot a small stream of coolant towards the header, so i would never see a mark from it. Finally I got sick of filling the tank. I sat in my driveway and reved the hell out of the car. I finally saw a bit of steam and just kept looking, finally found the hole. Replaced the hose and it was fine ever since.