Car info:
- 2013 Honda Civic, manual transmission
- Live in Tuscaloosa, AL, VERY HOT SUMMERS
- 98,000 miles
- Oil change less than 2 weeks ago
- Tires rotated today
- Lucas fuel injector cleaner used less than 500 miles ago
- Engine air filter replaced less than 3,000 miles ago
- Unclear whether coolant system has ever been flushed prior to the one I attempted this weekend.
Question:
I attempted a coolant flush this weekend. After I drained the old coolant, I filled the radiator with distilled water and ran the engine for about five minutes, revving it a few times. After the engine cooled, I drained the system. The water came out the same blue color as the Honda antifreeze/coolant. Once all of the water was drained, I filled the system up with Honda engine coolant, 50/50 mix as specified. After that, I ran the engine, and the car appears to be driving just fine.
However, I was only able to fill the radiator up with about a gallon of antifreeze, whereas the car's manual says the system has about a gallon and a third capacity. Can you think of any reason why the system only allowed me to pour in one gallon? Perhaps there is some remaining fluid in the radiator that I failed to drain? Is there any possibility it's a clogged radiator?
One definite possibility is that not all the coolant or water was flushed out of the engine block. (On many vehicles, there's an engine block plug to drain for the coolant that remains in the engine block). Whether after a single flush whether there's the flushed water or coolant in the engine block is an open question, at least in my mind.
As a practical matter, keep an eye on the engine temperature. If it's stable in variety of circumstances, well, given that you used distilled water, there really shouldn't be much of a problem, under normal driving conditions.
Did you take the thermostat out? It likely had some coolant left in the block if it didn't run long enough to open it.
You did not say you burped the air out of the system. You need to do that.
That's true. (It can be done without a funnel or with a special funnel with a variety of cap adapters). One tell-tale sign that the system has air is that the engine temperature will rise, particularly before there's enough pressure in the line to move the air bubbles along. It's good and necessary practice to "burp" the engine, when either flushing or draining and filling the coolant, to prevent those air bubbles from overheating the engine, and creating a problem that is expensive to fix, such as a head gasket leak or a cracked block.