RPM dependent heat???
 

I have been reading all of the old posts and doing as much as i could without adding more to the board but i am at my end.... When i run my car it warms up as usual but i get no heat. I have properly burped my system, replaced the thermostat, and i have checked the VSV. The heat will only start working around 2800-3000 RPM. Though i do know i have a small weep in my coolant system at one of the block connections. "about 1/2 overflow every 500-600 miles" Any ideas guys? :sadwavey:

You didn't install a failsafe therostat did you?

If not your heater core is probabally plugged or at least restricted so that the higher RPM's are pushing more antifreeze through as the water pump builds more pressure. And then when the RPM's are lower there isn't enough pressure to push any through.

failsafe??? is their a way to check other than to boil it? i don't have the box anymore.... it was just a basic one from Napa.

Basically if you take the thermostat out and you look at it. If it is stuck in the open position then its more than likely a failsafe. They have raised points near the bottom so if the thermostat opens too far cause the engine is overheating it forces it to stay open to prevent damage to the engine. This might be a stupid question but the antifreeze isn't dissappearing on you is it? You may want to check it right at the radiator cap. Let the car cool overnight and remove the cap first thing in the morning and then start the car. By looking into the radiator with it running you can tell two things. IF the fluid level is correct and also if your water pump is working. If its low add coolant and reburp it. You should see the antifreeze flowing in there as well. But usually you have to wait for it to get up to operating temperature before you see that. Two things to check. Good luck!