Despite the fact that BMWs are among the best engineered cars in the world and the company is a leader in many aspects of the automotive industry, many of the cars it produces can suffer from head gasket problems. This is caused by a few factors, namely the fact that BMWs often appear to have water pumps, thermostats and radiators that don't last long. There are some things that can be done to prevent a warped head gasket as well as signs to look for if you think you have a problem with the head gasket.
A failed head gasket is generally cause by an overheating engine that, in turn, causes the head to warp. If the head warps, the head gasket cannot properly seal the head to the block, allowing coolant to mix with the oil inside the motor. An engine will overheat for a variety of reasons. If the water pump fails on a BMW, it will stop circulating coolant from the radiator into the motor, causing potential overheating if the problem is not caught in time. If the thermostat fails, then the fan will not turn on and cause overheating. The least likely possibility is a failed radiator core, though this does happen as well.
There are several signs that a BMW has a blown head gasket, such as if the temperature gauge shows the car is routinely running hot. If the low coolant light comes on, even after topping up the coolant, it's leaking somewhere. Another way to tell is by opening up the engine's oil cap and inspecting the oil. If the head gasket is blown, the oil will mix with the coolant and the oil will have a brown, milky appearance. If white smoke comes out of the tailpipe even after the car is warmed, there is a good chance there is a problem.
There are several things you can to help ensure your BMW motor does not suffer from a blown head gasket. It is recommended you change the water pump every 60,000 miles or so and replace the thermostat if there is any sign of the motor running hot. Though radiators are expensive, it's a good idea to replace them every 100,000 miles or so. It is also possible to upgrade to an aluminium radiator on most cars as well as a better engineered aftermarket water pump. It's also a good idea to periodically have the coolant flushed and replaced.
What Happens if the Head Gasket Is bad?
If the head gasket blows on a BMW, fixing it is labour intensive. The head gasket itself is usually a £130 part, but removing the head takes many hours. Most shops charge around £975 to properly fix a head gasket.