Fixed the Blow head gaskit & aired out the system now i heater doesnt blow hot air out its just warm?

Question

Hello I have a 1994 Chevrolet Cavalier 4 cyl. it has about 82,500 miles on it. We just replaced the Head Gaskit becuase it was blown. Shorty after fixing it i took it down the road & did see that my car was getting hot once again..the temp runs at 1/4 and sits at 1/2 it was hitting 3/4 we found out the system was airbound & we fixed the prob. by airing it out but i did see that i would lose heat at times & or when it did work the heat wouldn't be hot just a little warm does anyone know how to fix this prob. or whats going on it with???


Thanks

Answer 1

Did you replace the thermoss stat when you did the head. If the car was overheating because of the had gasket chances are the thermo stat is no good.Replace it first then if no heat still pull the heater core hoses off and take a garden hose to them. Flush out the heater core reinstall heater hoses and top up coolant. That should fix it. If not does the temp reg on the heater control panel work . Check for a vacuum line off or pinched.Good luck hope I helped


GM tech for 20 years

Answer 2

One problem may be the heater core. It is like a radiator. If it is partially clogged, the water may not be going it thru like it should. It is better to buy a new one than replacing it with a used one. Check with the automotive stores and they all have different prices. I like autozone cause they have national service on warranties cuz they store them in the computers. I presume you did not have this problem before you did the repairs.


There is a duct that may also be partially blocked. If your heater duct is air activated you may have a vacuum leak (small probability). You will have to get a view of the duct, open and close the duct and see if it is closing fully or not. If you turn the heat off and it is coming thru still then you have one of the rubber hoses is lose or has a leak. If your duct if closing fully or if it it open fully, and still getting warm air then it is the heater core. If you put TOO MUCH antifreeze you may have a problem too. You water will not get hot and therefore when it passes thru the heater core, the air is blowing on warm water. That is one reason to use the correct ratio of antifreeze in your radiator. The older cars were directly linked to the duct to open or close it.

Answer 3

I did not hear you saying the motor is overheating which it means you did a good job on the head gasket part, so get a manual and 7mm 6 point socket and begin unscrewing nuts and remove that heater core, keep in mind that to air out it had to be done with the motor running , radiator cap out until reaching operating temperature with the heater turned on the highest setting , then cap the radiator.

Answer 4

if your temp is running were it should be most likely your heater core got some crap in it you may have gotten chunks of old gasket in the coolant when you were cleaning the block
check to see if both heat core hoses are at the same temp
if one is cold and the other is hot the cores plugged
you can flush the core by un-hooking the 2 hoses and run a garden hose trough them do it to both hoses

Answer 5

I would change thermostat if you have not done so already. I experienced this problem once and later discovered that the heater hoses going to the heater core had been connected backwards, after changing the connection heat came back.

Answer 6

I'm assuming you had your water pump checked. Thermostat and radiator cap changed. Your coolant isn't circulating properly. I'd try flushing the system and then have someone check the pressure on your radiator. A radiator shop usually doesn't charge much for doing this and they can narrow down the problem even more.

Answer 7

best way to "air out a cooling system (or bleed it out) is to use a suction device (used with compressed air ) or to use a filler funnel that rises above the engine & let the car bleed the air out @ idle & revving it to 2000rpm or so every 5min or so