1996 Toyota 4Runner radiator/cooling system

I recently had my water pump, hoses, thermistat and timing belt replaced. The car was fine for about 3 days. Now it overheats after about 10min of driving, especially when stopped at a light. It also smells like their might be coolant leaking inside the car on the passenger side. The mechanic said the head gasket was fine but mentioned that maybe the radiator could have deposits from too much water in the past and could cause heating problems. (Clogging in the system) I don't want to pay to replace the radiator if it is actually something else.