No heat!

[redbird98]

96 T/A. Takes forever to get any heat, i replaced the thermostat. temp gauge pretty much wont get any higher than 160 while driving, creeps up a little at stops. heat sucks at idle, gets better when driving but only after the car has been driven quite a ways. new thermostat did not help. I have bled the cooling system , there is no air in it. I can let it run for 20 minutes in the morning and get init and it still hasn't reached 160 on the gauge. I checked the fans thinking maybe they were running all the time, but they are not. Any suggestions? I think I might backflush the cooling system and heater core, and install a GM thermostat.

[0rion]

96 T/A. Takes forever to get any heat, i replaced the thermostat. temp gauge pretty much wont get any higher than 160 while driving, creeps up a little at stops. heat sucks at idle, gets better when driving but only after the car has been driven quite a ways. new thermostat did not help. I have bled the cooling system , there is no air in it. I can let it run for 20 minutes in the morning and get init and it still hasn't reached 160 on the gauge. I checked the fans thinking maybe they were running all the time, but they are not. Any suggestions? I think I might backflush the cooling system and heater core, and install a GM thermostat.

this is where I would start. Can you hear your blend door moving when you change the controls? Such as from vents to defrost, can you hear the vacuum to the door? Most likely a plugged heater core though. What about your coolant level and are you leaking any coolant?

[JaycenK]

Check all the stuff above but I'm almost certain you have a clog. There is a flow restrictor on the heater line going to the heater core from the water pump. This slows down the coolant speed through the heater core and also can allow for sediment to be deposited in the heater core which then causes a clog. I had the same problem last year and I did an engine build and here is what I found.
There are several places on an LT1 that like to clog on dex-cool coolant.
1. the heater core it's self. Usually disconnecting the heater lines and running a garden hose through it fixes this.
2. the heater hose with the flow restrictor in it. Again disconecting it from everything and running water through it will usually fix this.
3 Steam pipe on the back of the engine. This is usually a real PITA to deal with while the engine is in the car but some times you get lucky and the banjo bolts come out with out breaking or tearing up the head. This pipe will not effect heat in the heater core but will effect how easily the engines cooling system will bleed air. After flushing the engine it was a bear to get all the air out and it was due to the steam pipe being clogged. I had to jack the front end way in the air to get all the air out. I fixed all of these problems when I built the new engine. Some think if i can just get the engine bleed I am ok. WRONG. You can end up with detonation issues if the steam pipe is clogged as it connects to both heads and is the highest point for air to escape on an LT1. It should be inspected off the car if you have 100k+ miles on it. The reason is that some check the radiator to see if it is moving water back to it but if one side is clogged and the other is not you would never know. good luck with it.

[Bad Co.]

Keep me posted bro. Im having the exact same problem.

[murche]

Just flushed my heater core and solved my no heat condition. I highly recommend it.

[redbird98]

while i posted earlier that i had bled the cooling system, it fooled me. I flushed the heater core, but it was clean and flowed good right off the bat, but i could tell by the lack of coolant i lost when i took the hoses off, that the system could not have been full. So I spent about an hour bleeding air from the system. pouring coolant in while revving the engine then putting the cap on and letting it run while i cracked open the bleeders, then repeating the process over and over. Finally the upper hose and radiator cap were getting hot and the temp gauge started coming up until it reached normal temp. works good now.