Was just wondering if having soot in my intake is somewhat normal or is it time to swap an hX-40??? Also..... with my radiator cap off and the engine idling, coolant comes up and into the overlfow bottle. It is does not bubble like if I had a headgasket leak. . I just changed thermostat due to my old one opening late ( 190+ ). I honestly thought I had a gasket leak due to the pressure I would have in the coolant system. Now that I changed the thermostat, my gauge hardly fluctuates, stays right around 180, could I have too much fluid when I changed the thermostat? I am going to get coolant test kit tomorrow to hopefully end my possible headgasket leak..... I hope this isn't too confusing. . Thank you, Marc