Mercedes-Benz ML63 AMG Has A Coolant Leak

Diagnosing Coolant Leak Issues in Your Mercedes-Benz ML63 AMG and Effective Repair Strategies

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Reviewed by
Aisha
Written by RepairPal Car Genius
Updated January 14, 2025
0%
50% chance it's the
Loose Hose Connections
0%
25% chance it's the
Radiator
0%
25% chance it's the
Water Pump
The most common reasons a Mercedes-Benz ML63 AMG has a coolant leak are loose hose connections, a broken radiator, or a failed water pump.
  • Loose Hose Connections: A loose hose connection can lead to vacuum leaks or fluid loss, resulting in poor engine performance or overheating.
  • Radiator: A damaged or clogged radiator can impede coolant flow, resulting in engine overheating and reduced cooling efficiency.
  • Water Pump: A failing water pump can lead to coolant leaks or overheating due to inadequate circulation of coolant in the engine.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a Mercedes-Benz ML63 AMG has a coolant leak?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

When the head gasket begins to fail, the engine may have no symptoms at all. They only begin to occur when the leak has reached an engine oil passage, engine coolant passage or the engine cylinder.

When that happens, the engine may be very difficult to start, and run roughly when idling. There may be oil or coolant leaking, and the engine may begin to overheat, or at least run hot. At this point, there may be coolant in the engine oil pan — this will look creamy and lighter in color than the oil. Also, the radiator or engine coolant reservoir may have a gurgling sound, the presence engine oil, or smell of combustion. And the check engine light will come on.

The coolant being burned in the engine will produce white exhaust that smells sweet, like engine coolant. When the head gasket fails completely, the engine will overheat within minutes of starting, will stall and then won't restart.

A failing heater core may cause the car's interior to smell like engine coolant. The smell will become worse when the heater is turned on. The engine may also begin to run hotter until the vehicle is repaired.

The worst-case scenario is the engine overheating, which can cause extensive engine damage.

If the heater core is clogged, the air that blows when the heater is turned on will not be very hot.

Problems with the intake manifold gasket can create the following symptoms:

  • Illuminated check engine light
  • Erratic engine performance
  • Oil and coolant leaks
  • Poor gas mileage
  • Stalling

» LEARN MORE: Intake manifold gasket symptoms

A failing radiator can cause the engine to run hot or overheat. Most radiators are made of metal and plastic. The plastic parts can become brittle and crack over time, causing a leak of coolant (typically green or pink in color). All manufacturers have a recommended service interval for coolant renewal. As the coolant ages, the additives breakdown and being to form solid deposits. These deposits will build up in the passages of the cooling system and will eventually clog components, including the radiator. A leaking or clogged radiator must be replaced. Some automatic transmission cars will also have a transmission cooler integrated into the radiator. Lines going to and from the transmission circulate transmission fluid to help cool the transmission in heavy duty applications such as towing or off-roading. If this integrated cooler fails, it can allow transmission fluid and coolant to mix. This will causing shifting issues in addition to overheating.

A coolant leak may be noted from the hoses. Coolant hoses can be damaged by oil leaks, or age. This will lead to swelling or cracking, it is suggested to replace the hoses before they begin leaking to avoid potential overheating.

The bad thermostat can cause two different sets of problems, depending on whether it's stuck open or stuck closed.

A thermostat that is stuck open can cause the engine to run colder than normal and turn on the check engine light. It may also cause poor fuel mileage and the heater to blow cool air.

A thermostat that is stuck closed will cause the vehicle to overheat. If a new thermostat doesn't resolve engine temperature problems, the cooling system needs to be checked for other issues.

» LEARN MORE: Signs of a bad thermostat, and how to fix it

The two most common signs of a bad pump are leaks and noises.

Leaking water pumps can result in damage to the drive and timing belts, and cause the engine to overheat. A failed water pump can be caused by other problems in the cooling system, such as a bad thermostat, radiator or head gasket.

Troubleshooting Coolant Leaks in a Mercedes-Benz ML63 AMG

When tackling coolant leaks in your Mercedes-Benz ML63 AMG, begin with a thorough visual inspection of the coolant reservoir and surrounding hoses for any visible cracks or signs of wear. This initial step is crucial as it often reveals the most straightforward issues that can be easily fixed, such as replacing a damaged hose. If you notice the coolant level warning light on your dashboard, it’s a clear indication that further investigation is necessary. In cases where leaks are not immediately apparent, consider adding UV dye to your coolant; this method allows you to identify leaks more effectively by illuminating them with a UV torch in low light conditions. Additionally, pay close attention to the turbocharger coolant lines, as these can often be overlooked yet are common sources of leaks. By following this diagnostic approach, you can systematically identify and address coolant leaks, ensuring your vehicle remains in optimal condition.

How to Diagnose and Fix Coolant Leaks in a Mercedes-Benz ML63 AMG?

When tackling coolant leaks in your Mercedes-Benz ML63 AMG, it's essential to understand the common problems that can arise within the cooling system. One of the most frequent culprits is the deterioration of hoses, which can develop cracks or become loose over time, leading to leaks. Additionally, the water pump is a critical component that can fail, causing coolant to escape and potentially leading to engine overheating. Another area to inspect is the turbocharger coolant line, as this line can also be a source of leaks if it becomes damaged or improperly connected. By being aware of these common issues, you can systematically check each component, ensuring that you address the root cause of the leak effectively. This proactive approach not only helps in diagnosing the problem but also aids in implementing the necessary repairs, ultimately maintaining the performance and longevity of your vehicle.

Why is it Critical to Address a Coolant Leak in a Mercedes-Benz ML63 AMG?

Addressing a coolant leak in your Mercedes-Benz ML63 AMG is not just a matter of routine maintenance; it is a critical step in safeguarding your vehicle's performance and longevity. Ignoring a coolant leak can lead to severe engine overheating, which poses a significant risk of damaging vital engine components and could ultimately result in catastrophic engine failure. Furthermore, a coolant leak disrupts the engine's ability to maintain optimal operating temperatures, leading to reduced performance and efficiency. This inefficiency can manifest as sluggish acceleration and decreased fuel economy, detracting from the driving experience that Mercedes-Benz is known for. Additionally, the longer you wait to address the leak, the more extensive and costly the repairs can become, as the damage may escalate beyond the initial issue. By taking immediate action to fix a coolant leak, you not only prevent further damage but also ensure that your vehicle remains in peak condition, preserving its value and reliability. Therefore, it is essential to prioritize the repair of any coolant leaks to maintain the integrity and performance of your Mercedes-Benz ML63 AMG.

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