Coolant Changing
Never remove the radiator cap from a hot engine. Severe scalding may result.
Consider using distilled water for the coolant mix, it is much more pure than tap water.
Drain the system
Its good practice, and in some countries a legal requirement to collect the old coolant for disposal, rather than letting it run out on to the ground. This will also give a good indication of the capacity of the cooling system.
- Drain the old coolant from the system by removing the radiator drain plug on the vertical, and horizontal radiator if one is fitted. It is not advisable to use the engine block drain unless you have a new spare drain plug on hand.
- Empty the expansion tank and as best as you can, clean it inside and out. Be careful not to break the wires to the float assembly. Its best to secure the wires to the tank, with a cable tie around the circular base. Once its clean, refit it.
- Whilst the drain plugs are removed, Inspect and replace the rubber O-ring seals if they show signs of ware.
Initial Flushing
- Replace the drain plugs, and SLOWLY fill the system with clean water. Use an old jug and take some 5 to 10 minutes to refill the system.
- With the radiator cap off, run the engine at temperature for 10 minutes, with gentle revving of the engine.
- Allow to cool before draining the system again.
De-scaling
Depending on the extent of scaling, and silting up, the De-scaling section can be repeated.
- Replace the drain plugs, and SLOWLY fill the system with clean water, and a chemical flushing agent. Again take some 5 to 10 minutes to refill the system.
- With the radiator cap off, run the engine at temperature for 10 minutes, with gentle revving of the engine.
- Allow to cool before draining the system again.
Second Flush
Depending on personal choice, the second flush can be repeated.
- Replace the drain plugs, and SLOWLY fill the system with clean water. use an old jug and take some 5 to 10 minutes to refill the system.
- With the radiator cap off, run the engine at temperature for 10 minutes, with gentle revving of the engine.
- Allow to cool before draining the system again.
Filling with coolant
If you are fitting Toyota red coolant, it is a neat product and should not be diluted with water.
If you are using coolant other than Toyota's then the mixture of water and coolant needs to be a minimum of 30/70 coolant/water, and a maximum of 60/40 coolant/water. To much water and the mix is insufficient to fully protect the system. To much coolant wont absorb heat from the engine.
- Make sure that the drain plugs, and any hoses that have been loosened or disconnected are reconnected, and tightened, and if you haven't already, refit the expansion tank.
- Get a 5Litre bottle of coolant. SLOWLY pour half of it into your system .
- Add the same amount of water to the system using an old jug.
- Top up the bottle of antifreeze with water. This maintains a 50/50 concentration of antifreeze.
- Slowly add as much coolant as you can, but don't add any to the expansion tank yet.
- Turn both interior heaters to the hot position and turn them on.
- Gently run the engine until its up to its normal operating temperature.
- As the system warms up, any airlocks will gradually find there way out, so you will need to top up the filler neck as required.
- Now the system is full, you will see that the expansion tank already has some coolant in it. Top it up to near the "high level" mark.
- Replace the radiator cap
- Any coolant remaining in the bottle, can be stored and used for topping up, without altering the 50/50 mix.
It is important to check the level of coolant in the filler neck daily, as the level will drop, especially if tap water, rather than distilled water was used. Tap water contains air in it, as the water increases in temperature, the water is less able to hold on to the air, and some of it escapes. This is what happens in a saucepan of water before it actually starts to boil. This is what causes drops in the coolant level, after it has been renewed, and the only way of checking the level is to remove the radiator cap when the engine is cold. As a reminder, I tend to move the drivers seat forward, and tilted when I leave the car at night. When I come back to the car in the morning, I know I have to lift the bonnet and check the level.
Dave Bright, 25 Sep 2003.