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Persistent Coolant Loss & Overheating on 2020 Discovery

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David L. · rep 0 · May 25, 4:42 AM · 1 replies · solved · Question

Vehicle: 2020 Land Rover Discovery HSE Luxury

Hello everyone,

I'm having a really frustrating issue with my 2020 Land Rover Discovery (3.0L V6 Supercharged). For the past few months, I've been noticing a persistent coolant loss. I have to top up the expansion tank every couple of weeks, and I can't seem to find any obvious leaks on the ground.

Recently, the temperature gauge has started creeping up, especially in stop-and-go traffic, and I've even had a 'High Engine Temperature' warning pop up once or twice. No check engine light yet, but I'm really concerned about potential engine damage.

Is this a known issue with the 3.0L supercharged engine in the Discovery? What should I be looking for? I'm worried about head gasket issues, but I don't see any white smoke or milky oil.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:42 AM

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ClearTheCode admin answer:

Persistent coolant loss and overheating on a 2020 Land Rover Discovery with the 3.0L supercharged engine are serious symptoms that require immediate attention. While you haven't found a visible leak, the coolant is going somewhere, and overheating can cause catastrophic engine damage.

Common Causes of Coolant Loss & Overheating (3.0L Supercharged):

  1. Plastic Coolant Pipes/Fittings: The 3.0L supercharged engine is known for having several plastic coolant components (e.g., thermostat housing, crossover pipes, supercharger coolant lines) that can become brittle and crack, leading to slow, hard-to-spot leaks.
  2. Water Pump Failure: The water pump can develop leaks or internal failures, reducing its efficiency and leading to overheating.
  3. Expansion Tank/Cap Issues: A faulty expansion tank cap can fail to hold pressure, leading to coolant evaporation or leaks, or the tank itself can crack.
  4. Radiator/Heater Core Leaks: Small pinhole leaks in the radiator or heater core might not leave a puddle but can still cause significant coolant loss.
  5. Head Gasket/Engine Internal Leaks: While you don't see typical symptoms like white smoke or milky oil, an internal head gasket leak can allow coolant to burn off in the combustion chamber or mix with oil without obvious external signs. A block test can confirm this.
  6. EGR Cooler Leak: Some engines have an EGR cooler that can leak coolant internally.

When to See a Shop:

Do not drive the vehicle if it's overheating. Get it to a Land Rover specialist immediately. They will:

  • Perform a Pressure Test: This is the most effective way to find external leaks, even small ones. The system is pressurized, and technicians look for drips or listen for hissing.
  • Inspect All Coolant Hoses and Components: Pay close attention to plastic parts, especially under the supercharger and around the thermostat housing.
  • Use a UV Dye Test: Adding a fluorescent dye to the coolant can help pinpoint elusive leaks under UV light.
  • Perform a Block Test (Combustion Leak Test): This test checks for exhaust gases in the coolant, indicating a head gasket or internal engine leak.
  • Check for OBD-II Codes: Even without a CEL, codes like P0116 (Engine Coolant Temperature Circuit Range/Performance) might be stored.

Addressing coolant loss promptly is critical to prevent severe and costly engine damage.

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