Ok, let me start by saying this is really wierd......

Everything is hooked up on my car as it should be....I just changed the water/antifreeze and filled it back up, including filling the overflow tank half way. I put the cap back on as it should be and started the car. The top radiator hose got pretty hot fairly quickly, maybe within 2 minutes while all the other hoses were cool to the touch. I let the car run for about 15 minutes and watched as the temp gauge got up to about 220. All the while I had the heater on and set to HOT. For one, the radiator fan wouldnt come on until I turned on the A/C and it cooled the car back down....but what is really wierd/odd is the fact that the vents never blew warm air. But wait, theres more.......if I rev the engine just a tad while the heater is on, it would blow hot air, let off the gas pedal and back to cool air.

Could I have air in the lines somewhere/somehow? What would make it blow cool at idle, but warm while driving? If I move the slider to COLD it will blow cold A/C or just cool vent air. By the way, the overflow tank never pulled water out of it or put anymore into it. What's the deal? thanx.

 

Don't have any tech on how to do it but you may need to purge air from the system. My friend always leaves the radiator cap off until the thermostat opens and draws water into the block and dumps air into the radiator, he just keeps addidng coolant until the level stabilizes.

 

What vehicle, year, engine? That always helps to know.
I can only assume that it's a TBI engine since you mentioned a signle fan.
The fan does not turn on until around 230 degrees (somebody correct me if I'm wrong). So if your dash temp gauge was showing 220, that was not hot enough for the ECM to turn on the fan.
Since your A/C turns the fan on, you can safely assume that your fan wiring system is ok.

If the heater wasn't blowing any hot air until you raised the RPMs, that would be a sign of a weak waterpump.

The overflow tank serves as an overflow for when the engine heats up too much and needs to blow off air or hot water and also as a coolant reservoir for when the engine cools down, the cooling system pressure drops and it pulls in extra coolant to replace the void. Give it several driving cycles to establish balance in the cooling system, it needs to heat up and cool down several times to do that.

Let us know how it all goes.
Lou

 

Vehicle?? Third Gen Camaro Z28
Year?? 1986

Those two questions were answered in the TITLE. As for the engine, 5.0L Tuned Port Injection 305. And yes, it does have a single fan. By talking to another fellow car junky, he said there is probably air in the system and I should remove the left side (looking from under the hood view) heater core line and plug the other end then rev the engine until it pushes all the air out thru the heater core. I tried that, and yes alot of air did come out and it started pumping out antifreeze. I reconnected the line back to the heater core, started the engine again but it still blows cool at idle.

Can anyone confirm what "BigBabyLou" says......a few times driving and cooling back down should resolve the issue? Is there a different or better way to get the air out of the water system? thanx.

 

vzfox I can tell you what just worked for me. I removed the radiator cap when the car was cold, started it and let it warm up until the thermostat opened, then stuck a nickle or two in the throttle stop for a fast idle and then added coolant. As soon as you start the fast idle, the level in the radiator drops quite a bit. It`s a bit easier if you have a helper. When the coolant is up to the top of the radiator, install the cap and do a few cool down and heat up cycles and add coolant to the recovery tank as needed. Good luck.

 

Thanx guys.....I think most all of you were correct. After a few warm ups and cool downs along with the radiator cap removal and refilling.....my heater now blows hot at idle. Everything works as it should. "BigBabyLou" was correct on the 230 degree fan turning on also.....I watched as the needle went passed 220 and as it got ever so close to the red line, the fan came on and cooled it right down. Gotta admit, my heart was racing at the thought of an overheat escpecially with air in the system.

Thanx again guys......