Diagnose coolant leak Audi Q5

Diagnosing a Coolant Leak in Audi Q5 FY (2018-2024)

Tools Required

• Flashlight
• Cooling system pressure tester
• Mirror on an extendable handle
• Basic hand tools (screwdrivers, pliers, socket set)
• Safety gloves and goggles
• Drain pan
• UV dye and a UV flashlight (optional)

1. Initial Inspection

• Check Coolant Level: Verify the coolant level in the reservoir when the engine is cold. Add coolant if necessary.
• Visual Inspection: Look for visible signs of coolant leakage around the engine bay, radiator, hoses, and under the vehicle.
• Inspect for Corrosion: Check for white residue or corrosion around joints and hose connections which might indicate a leak.

2. Pressure Test the Cooling System

• Preparation: Ensure the engine is cold to avoid burns.
• Connect Pressure Tester: Attach the cooling system pressure tester to the radiator or coolant reservoir cap.
• Pressurize the System: Pump the tester to the pressure indicated on the coolant cap (typically around 15 psi).
• Inspect for Leaks: Look around the engine bay for any signs of coolant leakage. Use a mirror to check hard-to-see areas.

3. Inspect Common Leak Points

• Hoses: Inspect all coolant hoses for cracks, swelling, or leaks at the connection points.
• Radiator: Check the radiator for any signs of damage or leakage.
• Water Pump: Look for leaks at the water pump weep hole or gasket.
• Thermostat Housing: Inspect the housing for leaks or cracks.
• Expansion Tank: Check the expansion tank for cracks or leaks from the cap.

4. Using UV Dye (Optional)

• Add UV Dye: Introduce UV dye into the coolant system and run the engine to circulate.
• Inspect with UV Light: Use a UV flashlight to inspect the engine bay. The dye will fluoresce under UV light, highlighting the leak.

Repair Instructions

1. Replace Damaged Components

• Hoses: If a hose is leaking, replace it with a new one. Ensure clamps are tightened properly.
• Radiator: If the radiator is leaking, replace it. Drain the coolant, remove the radiator mounts, hoses, and connections, then install the new radiator.
• Water Pump: If the water pump is leaking, replace it. Remove the belt, unbolt the pump, clean the surface, and install a new pump with a gasket.
• Thermostat Housing: Replace any cracked or damaged thermostat housing with a new unit.

2. Refill and Bleed the Cooling System

• Refill Coolant: Refill the cooling system with the appropriate type and mixture of coolant for the Audi Q5.
• Bleed the System: Remove air pockets by running the engine with the heater on max until the thermostat opens, then topping off the coolant as the level drops.

3. Recheck for Leaks

• Re-Pressure Test: After repairs, re-perform the pressure test to ensure no further leaks are present.
• Monitor Coolant Level: Check the coolant level after a few drives and monitor for any signs of leaks.

Final Notes

• Safety Precautions: Always work on a cold engine to avoid burns.
• Dispose of Coolant Properly: Used coolant is toxic and should be disposed of according to local regulations.
• Professional Assistance: If the leak persists or if you're unable to locate the source, consider seeking professional assistance from a certified Audi technician.