How to.. Copen + Any car Cooling System Flush Procedure

Hey guys! I flushed my cooling system today and thought I should make a little guide of how I do it, for those that may not know how to. I find that this way is the easiest and 90% of the time you dont get any airlocks and don’t even have to bleed the system. . This procedure can be be used with any car :slight_smile: Just skip the parts that doesnt not apply to your vehicle :slight_smile:

Here are the tools you’re gonna need.
A set of hooks for easier removal of the radiator hoses. (Or a screwdiver will do. All up to you.) :slight_smile:

Your pliers of choice, for undoing factory hose clamps. I prefer these 90 degrees bent pliers.

A bucket, so we dont make a mess. (We all know what a bucket looks like so not including a photo of that haha.)
Floor Jack and Jack Stands if a hoist is not accessible. (You dont really have to raise the car up for this.)

Anyway here’s my procedure.

1st of all I raised the car up. (For easier access to the radiator drain plug.)

then I had to remove my engine cover. For better access to the hoses.

Once I got the car up, it gave me access to the drain plug. It’s on the bottom right hand corner of the rad.
Leave the radiator cap on first so you don’t spill coolant all over yourself. Once you’ve removed the plug, then you can remove the cap and let it rip. :joy:

Then once I’ve drained most of the coolant out. Went ahead and removed the radiator hoses. I like to take it off of the engine side, since old plastics tend to get brittle over time. You wouldn’t wanna break your radiator fittings especially if you have a Copen :joy: Better safe than sorry.

Once the radiator are hoses off, you’re also gonna want to remove one of the heater hoses. I went ahead and took the one off just behind the thermostat.

Now you might be wondering why?

You’re gonna want to remove the heater hose off so you could separately flush the engine / heater to make sure all of the old coolant and the gunk that’s accumulated in the cooling system over the years. Mixing some of the old coolant with new coolant could cause chemical reactions and start to create build up and over time blocking your radiator internally. First hook up your garden hose to either the heater hose or the fitting the hose came off of.

I hooked the garden hose up to the fitting the heater hose came off of, and that made all the water pass all through the engine and come out of the fitting that goes to the top radiator hose. Then once the water starts to get clearer, you’re gonna want to block where the water is coming out of, and that’s gonna force all the water out through your heater core. You’re gonna want to keep switching it around till the water is clear.

Once the previous step is done. Proceed to flush your radiator from the bottom-top first. this will push a lot of the crap that’s inside the rad out. Then once you see that there’s no crap comes out of the rad, then you can flush it top-bottom. And yes this whole procedure requires A LOT OF WATER haha.

After you’ve flushed the radiator, you can go ahead and put everything back together.
Mix up your prefered coolant. and start pouring!
DON’T FORGET THE DRAIN PLUG. Cos I forgot mine and when I started filling it up, I was wondering why it was leaking :joy: :joy:
Also if you can, while you’re at it might as well change the hose clamps, drain plug and radiator cap just for peace of mind.

Also don’t forget to bleed the system! I didn’t have to with my car. But you have to make sure, the heater is hot. Wait for the thermostat to open and close, just to be sure that you have no airlocks. and wait for at least one fan cycle before you call it quits.
Then voila. Enjoy your pretty coloured coolant and the benefits and peace of mind with a fresh cooling system :smiley:

Oh and I almost forgot. Don’t forget to wash out your overflow bottle!


Nice write up mate.

To bleed a system I usually jack up the front or park on steep driveway that has front in so radiator is the highest point.

Then remove the cap, top of fluid. Get a coke bottle and fill 3/4 with water and place on top of radiator so it’s in the hole (if your lucky the bottle will screw in)

Then start the car, heater on hot and air blowing.

Idle the car until up to temp, any bubble will be visible in the coke bottle, as bubbles come in water will go out.

Once bubbles stop, remove coke bottle spilling water on your legs and put cap on.


Excellent guide!
I would like to add if you stick an air gun in the there with the garden hose and spray air inside with the water the air bubbles act as an abrasive and help loosen up the scale and grime (not too much pressure please), it also helps if you remove the thermostat. You should use distilled or demineralised water as tap water could be too hard in some cases (hard = high calcium) to prevent further scale build up and use the correct ratio of water and concentrate as a mixture that’s too strong won’t work as well carrying heat.