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:
» 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.
To effectively diagnose a coolant leak in your 2012 BMW 740Li, begin by identifying common symptoms that may indicate a problem, such as a low coolant level or warning lights on your dashboard. Regularly monitoring the coolant level in both the reservoir and radiator is crucial; if you find yourself frequently needing to add coolant, this could signal a leak in the system. Next, conduct a thorough inspection of your vehicle for any visible signs of coolant, such as puddles or stains on the ground, which can help you locate the source of the leak. Additionally, remain alert for other concerning symptoms like engine overheating, white smoke from the exhaust, or a milky appearance in the engine oil, as these may point to more severe issues, including a blown head gasket. Addressing any suspected leaks promptly is essential to prevent costly repairs and potential engine damage. By following this structured diagnostic approach, you can systematically evaluate the situation and take the necessary steps to resolve the coolant leak effectively.
When tackling a coolant leak in a 2012 BMW 740Li, it's important to understand the common culprits that could be at play. One frequent issue is radiator leaks, which can occur due to wear and tear or physical damage, leading to coolant escaping from the front of the vehicle. Another potential source is the water pump; if it fails, you may notice coolant pooling beneath the car, indicating a significant leak. Additionally, worn or damaged hoses can compromise the coolant system, allowing fluid to leak out. Don't overlook the thermostat gaskets, as faulty seals here can also contribute to leaks. Lastly, severe head gasket problems can be a more serious concern, often requiring immediate attention to prevent extensive engine damage. By identifying these common causes, DIYers can take the necessary steps to diagnose and repair coolant leaks, ensuring their BMW remains in optimal condition.
Addressing a coolant leak in your 2012 BMW 740Li is not just a matter of convenience; it is a critical maintenance task that demands immediate attention. Ignoring a coolant leak can lead to severe engine overheating, which may result in catastrophic damage and costly repairs. The cooling system relies on a sufficient level of coolant to function effectively, and a leak can create air pockets that disrupt this process, further exacerbating the risk of overheating. Common culprits behind these leaks include brittle plastic pipes, worn-out hoses, and failing components like the water pump and radiator, which can deteriorate even before the vehicle reaches 100,000 miles. By identifying and repairing the leak early, you can avoid the financial burden of extensive engine repairs and ensure the longevity of your vehicle. Therefore, if you notice any signs of a coolant leak, it is imperative to act swiftly to safeguard your engine and maintain the performance of your BMW.
See what others are asking about their BMW 740Li. Get answers from RepairPal's community of auto experts and enthusiasts.
Read about related problems experienced by other BMW 740Li drivers like you.
