BMW 640i xDrive Coolant Leak Diagnosis Cost

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Coolant Leak Diagnosis
The average cost for a BMW 640i xDrive coolant leak diagnosis is between $44 and $56. Labor costs are estimated between $44 and $56. Estimate does not include taxes and fees.

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Coolant Leak Diagnosis

What is the cooling system?

The engine cooling system is made up of a set of components connected in a closed loop to circulate engine coolant through the engine, and maintain the coolant at a constant temperature.

How does the cooling system work?

As the engine runs, combustion events occur thousands of times per minute; heat is a byproduct of engine operation. To prevent that heat from destroying the engine, a liquid cooling system is used. Beginning with the engine, the cooling system uses coolant passages inside the engine block, cylinder head, and possibly the intake manifold. These passages allow coolant to flow through these components to absorb heat. The water pump pushes the coolant through the thermostat, and into the radiator, where it is cooled, then returned to the engine for another cycle. The thermostat regulates the temperature as engine coolant will not move past the thermostat unless the set temperature has been reached. This is a pressurized system, allowing the engine coolant to reach extreme temperatures without boiling off as steam.

What are the symptoms of a coolant leak?

When the cooling system is not working to its full potential, normally due to a leak, the engine will being to run increasingly warmer with time and vehicle use. This is because leaks tend to increase in size with time and use. Also, when a leak is present, the engine cooling system cannot maintain proper pressure, and this may result in boiling inside the engine cooling system. If boiling of engine coolant occurs, the engine will overheat immediately. These symptoms may cause the check engine light to illuminate, and the coolant temperature warning light will stay on unless the vehicle is cooled. Depending on the location of the leak, the smell of coolant may be evident inside the vehicle, outside the vehicle, or coming through the vents. Lastly liquid coolant may be noticed dripping onto other engine components, the ground, or even inside the vehicle.

Can I drive with a coolant leak?

Driving a vehicle with a faulty engine cooling system can result in overheating, cylinder head gasket failure, engine block failure, or cylinder head warping. It is never recommended to drive a vehicle with engine cooling issues, especially with modern engine casting materials.

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How often do coolant leaks happen?

Engine coolant leaks are typical for all vehicle's, old and new, without regard to mileage. Most vehicle's will leak coolant at some point in their useful service life. Factors that can lead to premature failure are driving conditions, driving style, age of components leading to brittleness and corrosion, and, most importantly, maintenance. Maintaining the cooling system will dramatically reduce the number of leaks the vehicle will have over time. The engine coolant can become corrosive over time, and if the manufacturer specified service interval for coolant flushing is not adhered to, the system will being destroying itself from the inside out due to corrosion.

How are coolant leaks diagnosed?

The first thing done when any cooling system issue enters a repair facility is to check the radiator cap. The radiator cap is often overlooked, but this vital component is responsible for maintaining proper pressure in the cooling system, and ensuring the system remains filled as the coolant grows and shrinks with temperature change. After the radiator cap, the vehicle will be inspected for obvious leaks, damage to cooling system components, and contamination in the coolant reservoir. If contamination from combustion exists in the cooling system, the leak is internal to the engine, and the engine cylinder block, cylinder head, and head gasket are suspected. If no leak is noticed, and no obvious sign of damage points to a diagnosis, the servicing technician will apply a pressure tester, and UV dye to the cooling system, causing the leak to become active, and visible with a UV flashlight. If no leak exists, the technician will being diagnosing individual component failure.

What will be the outcome of a coolant leak diagnosis?

Repairing a coolant leak typically requires draining the engine coolant from the entire system, removing the faulty part, and either cleaning or replacing that component before re-installation. If the leak is internal, the engine will typically receive a head gasket replacement, and the cylinder head must be sent to a machine shop to ensure it is free or warpage or cracking. Any evidence of cracking or warpage will result in replacement of the cylinder head with new. Once the vehicle is re-assembled, the coolant system will be refilled with coolant, bled of air, and tested to ensure the customer complaint does not return. Very often, repairing a leak involves a simple hose replacement, and coolant flush.

RepairPal Recommendations for coolant systems

Engine coolant flushes outside the manufacturer's maintenance schedule are one of the most common services repair facilities are known to needlessly recommend. However, there is a schedule for when these services should be performed. The factory scheduled maintenance section in the owner’s manual provides information for the customer concerning which maintenance items should be performed, and when they are needed. We always recommend following the factory scheduled maintenance intervals for preventive maintenance. If a leak is being repaired, and the coolant must be drained and replaced, flushing the coolant system should be performed if excessive corrosion is present, or if the factory scheduled service interval has passed.

What to look out for with coolant system leaks

It is a good practice turn the heater onto its highest setting if the engine begins to overheat. The heater core can act as a secondary radiator, but temperatures inside the vehicle may become unbearable. Some water pumps are fitted with a weep hole that allows a small amount of coolant to leak as a tale tell sign that the water pump has failed. To repair cooling system problems, significant deconstruction of vehicle may be necessary. This may include engine cooling fans, the radiator, body panels, the alternator, A/C compressor, mounting brackets, fuel lines, or any other component that interferes with access to cooling system components.

Can I diagnose a coolant leak myself?

The average DIYer can maintain the engine cooling system without much trouble. However, diagnosing the system can be a daunting task if the function of each individual component is not fully understood. If the cause of overheating is known, repairing the leak issue as a DIY may or may not be recommended. For instance, replacing a leaky hose is extremely low in difficulty. In contrast, since timing belt driven water pump replacement necessitates the removal of timing components, it is not recommended for the DIYer to attempt this task. A thorough knowledge of internal engine components, engine timing, additional systems, and several specialty tools are required to properly perform this repair. Likewise, if the heater core is leaking into the vehicle, the dashboard, and all dashboard mounted components may require removal to access the heater core. Since the airbag system, and much of the vehicle's electrical wires must be removed, a professional technician should be trusted with this repair to prevent damage.