I have a 2003 Toyota Camry LE, with 200k miles. Recently my head gasket went out so I worked with my dad on taking the entire engine apart and replacing that, along with replacing the thermostat, water pump, radiator cap, timing chain, and also ended up replacing 3 out of the 4 coils. Now I've run into the issue of the coolant in my overflow reservoir overheating to the point that its overflowing out of the top. This only happens when going 70-80 mph on the interstate after about an hour of driving. Any ideas as to what's going on now?

 

See your other post.