Hi my name is Matthew I've had my 1966 mustang for almost a year and I put a new engine in the car about 3 weeks after i bought the car along with an all new cooling system. today I was driving in the city and I got home and my car overheated waht could be a probable cause. My car's cooling system has atleast 5,000 miles on it. I also notice that i do leak a little coolant out of a bolt in my timing cover and water pump and My radiator does suck a lot of coolant out of my over flow tank.

 

Bad water pump, clogged radiator, air bubble in the system, faulty fan clutch (if so equipped). Last and worst would be bad head gasket or heads.

 

thnk you and would barsley from the old cooling system cause it to over heat because i'm noticing some black/ brown junk in the coolant that is in small chunks and in liquid form.

 

Black/brown junk? Like oil or solids?

 

A 66 with an overflow bottle?

Make sure you have the correct radiator cap.

 

yeah like little junk and some brown liquid that is diluted in the coolant when sturred up but when i open the radiator cap b 4 i start the car in the morning i can see both coolant and this brown junk. Could it be rust since its a bottom end rebuilt motor an it did have some rust in the heads, and the block.

 

Any grey discoloration to your oil?

Could be: Stuck thermostat - open or closed. Clogged water jacket, clogged radiator.