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Thermostat Replacement

BMW 740Li Thermostat Replacement Cost

The average cost for a BMW 740Li Thermostat Replacement is between $270 and $340. Labor costs are estimated between $167 and $211 while parts are priced between $103 and $129. Estimate does not include taxes and fees.

How Much Does a Thermostat Replacement Cost?

Thermostat Replacement Service and Cost

What is a thermostat?

The thermostat is a physical valve that controls engine temperature. It blocks coolant flow to the radiator until the engine reaches a predetermined temperature. This allows the engine to warm up quickly and efficiently.

How does the thermostat work?

The thermostat is controlled either mechanically or electronically. During engine warm up, it remains closed to allow the coolant in the engine to warm up. At a specific temperature the thermostat opens, allowing coolant to circulate through the entire cooling system. From there the radiator and radiator fan to take over temperature regulation.

What are the symptoms related to a bad thermostat?

A thermostat that is stuck open can cause the engine to run colder than normal and set 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 the new thermostat does not immediately resolve engine temperature problems, the cooling system needs to be checked for other issues.

Can I drive with a thermostat problem?

A thermostat that is stuck closed can cause the engine to overheat. An overheating engine should be shut off, and the vehicle towed. Overheating can cause coolant leaks, steam for the engine, a blown head gasket, and ultimately a failed engine if driven for too long. If the thermostat is stuck open it may not cause engine failure, but poor running, an ineffective heater, and increased fuel consumption may result.

How often do thermostats need to be replaced?

Replacement intervals vary greatly by vehicle and driving conditions. The thermostat does not wear like a tire or a ball joint, but will eventually fail and require replacement. Often times the replacement of the thermostat is recommended as preventative maintenance any time the cooling system is being serviced, such as during radiator hose replacement or a timing belt service.

Thermostat Replacement Repair Information

How are thermostat issues diagnosed?

A comprehensive inspection of the entire cooling system will be performed, including the water pump, heater hoses, cooling fans, and thermostat. With the engine off, the technician may perform a pressure test to ensure the cooling system is sealed. Radiator hoses will be inspected and should be replaced if old or leaking. Brittle or oil soaked hoses could fail soon after replacement, necessitating additional repairs. Where applicable, any trouble codes stored in the engine's computer will be pulled and the relevant diagnostic procedures will be followed. The engine temperature sensor may be tested, and the thermostat opening temperature checked. If the engine has overheated the shop will inspect for signs of engine damage. Modern engines commonly have composite (plastic) parts such as intake manifolds and thermostat housings that can warp from engine overheating. These parts, along with the head gasket, should be checked for leakage.

How is a thermostat replaced?

To replace the thermostat, the technician will drain the coolant from the system and remove the thermostat housing and thermostat from the engine. Many modern engines have thermostats that are integral to the thermostat housing and require complete replacement. In all cases, the sealing surface between the thermostat housing and the engine is cleaned, and the thermostat gasket is replaced. Once the new thermostat is installed, the cooling system is filled with fresh coolant and the system is bled of any air, then rechecked to ensure a proper repair.

RepairPal Recommendations for thermostat issues

Inspect the thermostat housing for corrosion, a corroded housing may prevent connected hoses from sealing properly, and could fail soon after replacement. Be sure to note the orientation of the thermostat. An incorrectly installed thermostat will make the cooling system more difficult to bleed of air and may not open, leading to cooling problems after replacement. When replacing the thermostat, consider replacing the relevant hoses as this would be a convenient time to do so.

What to look out for when dealing with thermostat issues

First and foremost, check that the Radiator or Coolant Reservoir are filled to the correct level of coolant! A low coolant level will continue to cause issues even after suspected parts are replaced. A proper diagnosis of any cooling system issues should be performed, including a pressure test to check for leaks. A stuck thermostat, leaking head gasket, or even a failed Radiator cap could cause an overheating issue. Depending on the age and condition of the cooling system, related or conveniently located parts should be replaced at the same time. Hoses, fan clutches, and any other component that requires draining the cooling system to service and are near their end-of-service life should be replaced. Also, refrain from using any “leak stopper” products in your cooling system. While they may appear to save money in the short term, their ability to stop leaks will also eventually clog and stop circulation in the cooling system. This could affect the radiator, heater core, and engine coolant passages.

Can I replace the thermostat myself?

Repairing your own car is an extremely rewarding process that can also save you money. But before you dive in, it’s important to be sure the issue has been properly diagnosed. Seemingly obvious symptoms can lead the inexperienced down a rabbit hole of replacing parts that don’t fix the problem. Proper diagnosis can save more money than guessing at what’s broken! If you're unsure you have the right tools or experience to diagnose a problem, consider reaching out to a RepairPal Certified Shop. The vast majority of thermostats only require simple tools to replace. However, the procedures vary wildly from car to car. Before ordering parts or attempting this repair yourself, look online for guides on how to replace the thermostat in your specific vehicle. Significant disassembly of the front of the motor, or hose specific tools may be needed. Special procedures may also be required to fill and bleed the air out of the Cooling System.

Most Common BMW 740Li Repairs

Parts
Labor
Average
Parts
Labor
Average