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Coolant Flush

There are many reported incidents of the Hilux Surf overheating and causing a cracked head (several hundred pounds to fix). The general consensus is that the coolant and/or thermostat is the problem.

Tools/Equipment Needed

  • 5 litres of Coolant.
  • 5 litres of Distilled/Demineralised Water.
  • Cooling System Cleaner.
  • Cooling System Lubricant (optional).
  • 12mm socket.
  • Bucket/container.
  • Garden Hosepipe.

Make sure the engine is cool.

Remove the radiator/coolant cap (A).


Remove the lower bash-plate by removing the four bolts (A).


Place a bucket under the radiator drain pipe and turn the tap (A).

You can also remove the lower radiator pipe (B) to speed up the flushing.

Remove existing coolant from the coolant resevoir (A).  

When you think most of the coolant has been drained, re-connect all hoses and close the radiator drail tap.

Refill the system with fresh tap-water and a bottle of coolant system cleaner.

Put all heater controls (front and rear) in to highest heat position.

Run the engine up to normal operating temperature.

Rest the engine to allow it to cool to a safe temperature.

Undo the radiator drain tap and lower radiator hose and flush the system with a hosepipe.

Allow the system to drain completely.

Re-connect all hoses and close radiator drain tap.

Refill the radiator and reservoir with a 50/50 mix of distilled water and coolant (I also added a bottle of coolant system lubricant).

Run the engine for a minute, then check the coolant level and top-up if necessary.

Check the coolant level frequently.


I have taken a lot of time to ensure the information above is correct, but please remember vehicle manufacturers make alterations and design changes during the production run of a vehicle. No liability can be accepted for loss, damage or injury caused by any errors in, or omissions from, the information given above.

If you think any information is incorrect, confusing, misleading or incomplete, please feel free to contact me.

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