how much coolant?

[silver8thcivicr18]

I flushed my radiator.How much to fill it back up to normal?

[vtaaakkk!!]

check your owners manual, or call the honda dealership. you using honda type II coolant?

[07mugencivic]

i check the manual doesnt say,,,

just buy 2 gallons

[vtaaakkk!!]

what i did when i put coolant in was fill it up slowly till it gets near the top and when it does leave it for a few minutes to let it settle then top it off. our cars have an overflow tank so if you think you put too much check it.

[The Power of Dreams]

Originally Posted by 07mugencivic

i check the manual doesnt say,,,

just buy 2 gallons

Sure it does. P. 293 of the 2008 Civic Owner's Manual. It's in the "Specifications" section in the back. For a coolant change, it's 1.19 gallons for the Si. Total amount of coolant is 1.80 gallons.

[07mugencivic]

my 2007 dosent have it

[The Power of Dreams]

Originally Posted by vtaaakkk!!

what i did when i put coolant in was fill it up slowly till it gets near the top and when it does leave it for a few minutes to let it settle then top it off. our cars have an overflow tank so if you think you put too much check it.

Coolant only flows into the coolant overflow reservoir when the coolant system pressure exceeds that on the radiator cap.

[vtaaakkk!!]

Originally Posted by The Power of Dreams

Coolant only flows into the coolant overflow reservoir when the coolant system pressure exceeds that on the radiator cap.

cool beans, i did not know that. guess you learn somethin new everyday!

[redvtech07]

Originally Posted by The Power of Dreams

Coolant only flows into the coolant overflow reservoir when the coolant system pressure exceeds that on the radiator cap.

well there is more to it than that. When the car is cool there will be less coolant in the overflow tank.... when the car is hot there will be more coolant in the overflow tank. This is because as the liquid gets hot and cool it expands and contracts

[The Power of Dreams]

Originally Posted by redvtech07

well there is more to it than that. When the car is cool there will be less coolant in the overflow tank.... when the car is hot there will be more coolant in the overflow tank. This is because as the liquid gets hot and cool it expands and contracts

I was responding to:

Originally Posted by vtaaakkk!!

what i did when i put coolant in was fill it up slowly till it gets near the top and when it does leave it for a few minutes to let it settle then top it off. our cars have an overflow tank so if you think you put too much check it.

You can't really overfill the radiator. Once the coolant level reaches the bottom of the filler neck, the radiator is essentially full. However, the cooling system must be purged of air. This can only be accomplished when the thermostat is open (cooling fans have cycled twice). After the thermostat is open, then you add more coolant until it reaches the bottom of the filler neck.

Now, coolant only flows into the coolant overflow reservoir when the cooling system pressure exceeds the pressure on the radiator cap. That is because there are two valves inside the radiator cap: a pressure and a vacuum valve.

Once the pressure exceeds approximately 13-15 psi, the pressure valve opens and coolant flows into the colant overflow reservoir. That is why the coolant should be no higher than the "MAX" line or between "MIN" and "MAX." If there is too much coolant in the overflow reservoir, the coolant may overflow when/ if coolant flows into the reservoir.

Next, when the vehicle is turned off and the temperature of the cooling system decreases, so too does the pressure in the cooling system. As the pressure decreases, a vacuum is created, causing the vacuum valve to open and the coolant inside the overflow reservoir is pulled back into the cooling system. If there is no coolant inside the overflow reservoir, this vacuum would suck in air. An excess of air inside the cooling system will cause the engine to overheat because the air is a poor coolant compared to the ethylene glycol/ water mixture. Air can also block coolant flow through the cooling passages if the air bubble is large enough.

Anyway, my point was that you cannot determine if you overfilled the radiator by looking at the overflow reservoir with the vehicle off. The car must be purged of air (thermostat open) and only after the car has cooled back down should you add coolant to the overflow reservoir (up to the "MAX" line).

[Edirol]

So under normal conditions, if the car is left to sit overnight and I check the reservoir in the morning, it should always be at the max line? Or would coolant need to be topped up once in a while due to evaporation? I'm asking because after a couple of months, I see that the coolant level in the reservoir dips down to the low line and I top it up again.

[bouncer07]

The Civic SI doesn't need a flush on any fluid (except brakes). Drain and refill.

[The Power of Dreams]

Originally Posted by Edirol

So under normal conditions, if the car is left to sit overnight and I check the reservoir in the morning, it should always be at the max line? Or would coolant need to be topped up once in a while due to evaporation? I'm asking because after a couple of months, I see that the coolant level in the reservoir dips down to the low line and I top it up again.

What you do is this...

Top off the radiator to the bottom of the filler neck.
Turn the car on and let it heat it up until the thermostat opens (radiator fan has cycled twice). The coolant level will then drop.
Shut the car off.
Fill the radiator up to the bottom of the filler neck.
Place the radiator cap back on the radiator.
Then, fill the coolant reservoir to "MAX."
In the morning, or after a few hours of allowing it to cool, refill the reservoir to "MAX."

After that, you should not have to refill the reservoir anymore for a long time. Evaporation will reduce the amount of coolant over time, but not by a significant amount.

At 12,000 miles (about 9 months), I've only had to add about half a cup of coolant to the reservoir (it used to be at "MAX" but I found it halfway between "MIN" and "MAX" last time I inspected it).