I have had some problem with my heat since I added stop leak to my radiator. I have since replaced the radiator, but for the time being I had to run it with stop leak before I replace the radiator. My problem is that I have heat only when I put my foot on the throttle. When the car is idle, the car runs cold air only. Did I possibly clog the heater core. What can I do to best fix the problem? Thanx
Robert

 

if the core is clogged, you should have one hot hose and one cool-ish hose. i'd definitely start there. how old is your water pump? any temp issues with the engine as well?

 

The water pump must be original. The car runs perfectly cool in the summer and winter at the right temp. The gauge never rises over the 220 mark when idling. The fan comes on as it should.
So could the water pump be clogged also? Which water pumps are recommended for replacement on our cars, if I replace it?

 

Stop leak is always a bad idea unless you are on your way to trade it in. You might have clogged the heater core, or you might just have air in the system. Check temp of both hoses as posted above. Stop leak will not clog a water pump, but I could see how when you rev it up the water is getting forced through the core.