Hello family,

I just drained the coolant from my 2008 C6 radiator. Am I just suppose to refill the coolant reservoir and thats it? I don't see a radiator cap.

 

That's a question I have also????

 

Yes. Remember even though the radiator is drained there are still a couple of quarts of coolant in the engine block. To get them out I usually drain and refill with clear drinking water and run the engine a couple of times until the drained fluid runs clear. Then I add the proper amount of Dexcool and finish off with water if needed.

It is easier if you don't use a 50/50 mix since there will always be some fluid left over in the block. If you use straight antifreeze you just add the number of quarts required to get 50% of the mixture. With a 50/50 mix you have to compensate for the fluid in the block.

Bill

 

BIll,

I added the coolant but it seemed as if the temperture for my car is rising, I turned it off already now. Where do you add the water?

 

I believe from reading past posts that the fluid, water/antifreeze is added via the overflow tank, as there is no radiator cap.

There was also some earlier discussion of running the engine with the overflow cap off to evacuate any air in the system that will cause elevated engine temps. Thus burping the engines cooling system and getting the correct amount of water/coolant into the cooling system without air bubbles.

George

 

You add the water at the same point that you added the antifreeze. If you are getting overyheating you may have an air bubble in the system. Did you follow this procedure:

1. Slowly fill the surge tank with coolant and water until the level reaches the base of the surge tank fill neck.
Important: Monitor the surge tank coolant level closely. The surge tank coolant level will begin to decrease once the engine is started.
2. Start the engine and allow to the engine to idle.
3. Allow the engine to idle for approximately 4 minutes.
4. Slowly fill the coolant mixture until the level stabilizes at the base of the surge tank fill neck.
5. Run the engine between 2,000-2,500 RPM for approximately 2 minutes.
6. Allow engine to idle and add approximately 1 liter (1.1 quarts) of coolant to the surge tank.
7. Install the coolant pressure cap. Shut the engine OFF.
8. Allow the engine to cool.
9. Top off the coolant as necessary.

Bill

 

Your complete cooling system holds 11.9 quarts of coolant. This includes the heater core, engine block, hoses, etc...
When you drain the radiator, you only get about 1/2 or less of the total system drained.

Here is my proceedure. Gets rid of a lot more coolant and allows you to flush the system with fresh water better.

1. With engine cold, remove the petcock to drain radiator.
2. Disconnect lower radiator hose at thermostat and remove thermostat to allow coolant system flushing.
3. Disconnect upper radiator hose (either end).
3. Disconnect one of the heater hoses.
4. Flush the engine and heater core thru the disconnected heater hose and connection until the water runs clear out the thermostat housing.
5. Flush the engine and radiator thru the upper radiator hose and connection until the water runs clear out the thermostat housing and radiator petcock.
6. Let drain.
7. Using an air compressor and blow-off tool, blow air thru the hoses and connections to force as much water out of the system as possible.
8. Put everything back together.
9. Check your owners manual for the cooling system capacity (11.9 quarts I believe).
10. To ensure you end up with a true 50/50 mix - add 6 quarts of of 100% coolant (not 50/50 premix).
11. Top off system with water. You will not be able to get 6 quarts of water in the system due to water being left in the block.

Longer & more complicated process but you ensure that you have flushed the cooling system good and that you end up with a true 50/50 mix in the end.

 

I drained 8 quarts of coolant from the radiator when I did my thermostat change. Two 1 gallon containers filled from the petcock. Your statement of only getting 1/2 or less out by draining the radiator is incorrect.

 

Ok. So you still have 3.9 quarts of mix in the system.
On a lot of vehicles you can't even get 1/2 out I have found.

 

It's not intuitive but there is more coolant sitting in the block than most people think. Be careful when doing any flushing of the system with a hose or an air compressor as it is fairly easy to damage the heater core with excess pressure. The coolant system will only allow about 15 psi in normal operation and it is very easy to double or triple that with a garden hose if not careful.