Coolant Drain, Flush & Replacement on 2003-2007 Accord

Stay tuned for the complete procedure, but first… Do you run plain tap water in your car’s cooling system? If you do, in simple words, trouble is coming! Coolant is superior to water in cooling systems in at least these 3 ways:– First, coolant has a higher boiling point than water. When water boils it turns to steam. Steam is not as efficient in cooling as liquids. Liquids conduct heat better than gases and thus will better conduct heat from the engine to the radiator for cooling. Your car is at risk of overheating if you use water.

– Second, coolant has anti-rust properties, so it will help deter corrosion/rust in the cooling system. Plain water will predispose to rust in the cooling system, rust will lead to leaks. Besides, corrosion/rust debris if can occlude the tiny cooling lines predisposing your vehicle to overheating.

– Third, reason…hmmm…#scratches#…because its cool to use cooooooolant! It makes your car stay cool :/

I did this DIY some 2 years ago when I switched from the regular green coolant to the blue Honda all season long life type 2 coolant. Down to business. It’s dirt time!

Materials: Honda all season type 2 coolant – 5.0L for auto transmissions, 5.1L for manual tranny’s and 6.7L for V6 (if you can’t get the Honda brand, Prestone is good although Honda claims only theirs is good enough…#coughs# not so…#coughs# sure) , 10mm wrench and pliers.

My materials...Using the European brand of the good Honda stuff

My materials…Using the European brand of the good Honda stuff

1. You may need to raise the vehicle enough to fit the receptacle that will receive the old fluid. If so, raise the vehicle and support on stands. You will not need to go under the vehicle for this procedure. This is done on a cold engine. Turn the ignition to the “ON” position, then turn the temperature dial all the way to max heat. If your car has the auto AC, turn the key to ON, making sure the DUAL is off, then turn the temp dial to 32oC then remove the key.

2. Remove the radiator cap. Locate the radiator drain bolt. Stand in front of the vehicle then look straight down behind the radiator to find the bolt. Unscrew. Mine was really difficult to unscrew so I used the pliers to get it going.

Coolant drain 2003 Accord

Drain bolt is shown by the orange arrow

Coolant drain and refill Accord

Drain bolt removed! NB coolant has been drained here

3. Drain the coolant into the receptacle. Replace the coolant drain bolt and tighten. My coolant was dark green. I had been using a less than desirable brand for long out of ignorance and unavailability of the Honda fluid. This is why I flushed the system. Note that coolant is poisonous, so pour into an empty container e.g. empty gallon and seal. Pets can get drink and get poisoned.

Drained coolant.

Drained coolant.


Loosening the 10mm bolt

4.Remove the single 10mm bolt holding the coolant reserve tank. Wash this and reinstall.


Removing the coolant reservoir tank




4. Flushing the system: If you have been using the Honda or other genuine coolants, this step is not necessary. skip to the next. However, if you are/were like me at the time, flushing would help remove contaminants. Fill the radiator with distilled water (A simple source of distilled water is the water that drips from AC systems. You can also buy this from the market) up to the base of the radiator neck(coolant should be just beneath the overflow outlet). Be patient radiators do take some time to fill up. Start the engine, allow to get to operating temperature, then rev the engine a couple of times. Shut off, allow to cool to touch, then drain the water. Do this until you have no more contaminants coming out of the radiator.

5. Refill: Fill the radiator with coolant up to the base of the filler neck. (a) Start the car and run for about 30secs then kill the engine. (b) Fill the radiator again to the same mark, fill the reserve tank and install the cap for the reserve tank, tightening fully. Screw on the radiator cap until the first stop (this will allow trapped air in the radiator to escape as you run the engine). (c) Start the engine again and run until the cooling fan comes on twice. (d) repeat step b. (e) Start the engine for the last time and rev at 1500RPM until the cooling fan comes on. Shut off the engine and top up both radiator and reserve tank if short. Tighten radiator cap fully.

The good stuff going in!

The good stuff going in!

6. Its good practice throughout the times in this procedure that the engine comes on, to have your eyes at the temperature indicator. Once during my flushing cycles, the temp went above the normal range. I killed the engine and behold, I didn’t fill adequately. I will also advice that you monitor the temperature gauge and coolant level during the first few drives after this procedure, just as an extra precaution to detect under-filling.

NB: Coolant should be replaced at 120k miles or 10years, after this, every 6ok miles or 5 years.


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