Coolant Flush & Fill
Coolant degrades over time and needs replacing every 4-5 years on most cars. A flush removes rust and scale that build up in the cooling system, helping prevent overheating, head-gasket failure and corroded heater matrix.
Comprehensive — covers radiator, heater matrix and engine block. Universal process.
THE ENGINE MUST BE STONE COLD. Hot coolant is pressurised — opening the cap will spray near-boiling fluid and cause serious burns.
Use the EXACT coolant type your handbook specifies. Mixing OAT, IAT and HOAT coolants causes them to gel and block the system.
Buy pre-mixed coolant where possible — avoids ratio mistakes. Concentrate must be diluted with DISTILLED water, never tap (minerals scale up).
After filling, drive to operating temp with the heater on full to bleed air out of the heater matrix. Top up cold the next day.
Wait until the engine is COLD (overnight is safest)
Open the bonnet and remove the radiator cap (or expansion tank cap)
Place a large drain pan under the radiator. Open the radiator drain plug (petcock)
Let it drain fully — usually 10-15 minutes
Close the petcock and fill the system with distilled water
Run the engine to operating temp with the heater on max (flushes the heater matrix)
Let it cool fully, then drain again. Repeat if the water is still discoloured
Close the petcock and fill with the correct coolant (pre-mixed or 50/50 with distilled water)
Top up the expansion tank to MAX. Run the engine, watch for leaks, top up as it bleeds air
Check the level again the next morning when fully cold — top up if low
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