Changing the coolant in a 2000 Civic cx


I drained the radiator, pulled the lower radiator hose, pulled the thermostat housing, removed the thermostat and replaced the housing. I reconnected the lower radiator hose and undid the upper one. I put the garden hose into the radiator and had the upper hose coming out of the block into a drain pan. I turned the water on, started the car and no coolant ran into the pan. What am I doing wrong? I followed the proceedure in the haynes manual. Im afraid to let the car run long since I dont know how hot its getting. I dont know if there is any coolant inside the water jackets. Even supposing I succeed in flushing the system, wont I end up with a lot of tapwater in my coolant? Thanks.


And why in the name of Thor are you doing this yourself?
You’ve probably drained deadly chemicals into your driveway, yard & storm drains.Not to mention what you’ve done to your car!
Hope you had fun trying to ‘save money’ by doing it ‘yourself’.
Now…hook all of the hoses back up, pour as much water into the radiator, put 2 gallons of water in your trunk & take the car to a garage!!! And PRAY!

#3 you have cats? Pet cats, outdoor cats?? Cats LOVE antifreese…


Its called a drainpan and it catched the antifreeze that you drain out…
Animals are only attracted to ethylene glycol, not propylene glycol.
If you have ever looked at a haynes/chiltons manual or done any simple preventative maintenance yourselves, youd know why it needs to be done.


Yes, dear it needs to be done. But it is not worth my time & frustration to try to do it at home, Chiton’s or whatever manual.
And, dear, I HAVE done the antifreeze flush & I’ve done oil changes & I even know how to change/gap spark plugs! I was probably doing that stuff before you were born.
With the newer cars it is much simpler to let mechanics deal with all of it.
I’m getting lazy in my old age, I guess…


You may want to remove the thermostat while flushing, if you didn’t already, since the thermostat keeps the coolant in the block until it’s at the proper temperature. Also, if you drained a large majority of the coolant, the delay could just be the tapwater getting through the engine block. Last thing I can think of is that there’s air in the cooling system and the water pump is cavitating (that is, pumping air and not coolant) which would also cause a major delay.

And I agree with you, OP (I;d say your name, but I can’t because the damn message ‘window’ blocks the post.) I’d rather do something myself than pay someone else money to do it, when I can do it just fine. Good luck.


I commend you for your DIY approach and I hope you will just ignore the foolish comments of the ill-informed.

The idea of flushing the cooling system is to fill it with tap water and to let the engine run until warm (cooling system is closed) so that the thermostat can open. Then re-drain. You are simply trying to flush out any remaining sediment particles and/or flush chemicals, if used.

Flushing is completely optional. A simple drain-and-refill is really all you need. And you needn’t worry about residual tap water left in the system before adding fresh coolant. It is of no consequence.

Yes, rinse away any standing puddles of coolant that result from your operations. That renders everything harmless. But you apparently know this already.


At the base of the upper radiator hose is the thermostat, and when its cold, it won’t let anything through. There is a bolt nest to the hose at the base, its the bleed screw, remove it and old coolant will rise out of the engine and run all over the ground, but you can clean that up later. There is also a block drain, I believe it is near the oil filter, again its just a bolt, kind of like the oil drain plug.

At this point in time, I’d suggest that you drain the block and radiator, then put the plugs back in. Hook up all hoses but remove the bleed screw. Premix your coolant with distilled water, a little rich if you like, especially if using Propylene Glycol. Propylene Glycol can be run at 100%, Ethylene Glycol cannot be run richer that 2:1.

Fill until the premix comes out the bleed screw, then put that in and finish filling the radiator.


One more thing. Propylene Glycol is toxic as well, just less toxic. Both Propylene Glycol and Ethylene Glycol break down in the environment and both are contained in modern medicines and foods, but in very tiny amounts. Read the label on a bottle of Nyquil.


Alright thanks everyone, Ive gotten it. I had already taken the thermostat out when I posted the initial question. The trick was just giving the block enough time to fill back up by adding the water more slowly with the hose. I got a nice stream of clear water out of the upper radiator hose and I even undid the heater core hoses again just to be absolutely sure that they had gotten flushed, all nice and clear. Ive just got to replace the thermostat and fill it up.
Incidentally, Im pretty sure only the VTEC and Integra models have the air bleed bolt at the thermostat housing. I wish the SOHC Hondas did. Thanks again for the tips.