I recently removed and replaced my rear exhaust manifold and knocked of the hoses off the control valve. Does the check valve go on the aft hole? Why is my heat quitting at idle? If I rev it up in neutral heat comes back. Works great while I'm on the highway whats up????????????? I saw other pics on the site and it shows the check valve in the aft hole. If I put the car in neutral or power brake the car the heat works fine!

Mike

 

sounds like low coolant to me.