when you get an engine hot it will dislodge junk in the system. this lodges in the heater core and plugs it. so no heat. if this is the prob, you might be able to dislodge with reverse flush but usually you have to take out the heater core and have it cleaned or replaced.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.