Fixing a McLaren MP4 – 12C Water Pump Leak

While the McLaren name is unfamiliar to the general public, aficionados know it as the upstart British manufacturer challenging Ferrari and Lamborghini in the supercar marketplace. Low and compact, McLarens are packed with technology and great to drive. Inevitably though, that makes them tricky to work on. At EurAuto we have some experience with McLaren service and repair work and here we’ll share how to deal with one of the more common problems, a leaking water pump.

Know the Car

Although McLaren has built road cars since the late 1990’s their first “volume” production model was the McLaren MP4 – 12C. Sold between 2011 and 2014, this was a RWD, mid-engined two-seater powered by a turbocharged 3.8 liter V8, and it’s the model we’ll be discussing here.

Mid-engined” means the engine is located between the seats and the rear axle. While that’s great for balance it’s not so good for cooling. Two radiators take heat away from the engine, and coolant circulation is provided by a large and powerful water pump.

A second result of the mid-engine layout is restricted access to some of the main components. The MP4 – 12C isn’t as difficult to work on as some European exotica, but it’s not like run-of-the-mill sedans and SUVs. To prove that point, the water pump is reached from underneath.

Spotting a Water Leak in Your McLaren MP4 – 12C

The water pump in this car is prone to leaking from the weep hole. When you get a water pump leak like this it’s best to replace the unit as soon as you can. However, as it’s hidden by one of the underbody covers it’s only visible when the car is in the air being serviced.

For many McLaren MP4 – 12C owners the first indication of a water pump leak is a low coolant warning. Ignore this at your peril because there’s a very real risk of “cooking” the engine, especially if you enjoy driving it hard.

Before the warning light comes on you may notice the sweet smell of coolant in your garage when the car has stood a while. You may also see coolant on the garage floor, which means it’s been leaking long enough to find its way past the underbody covers. Alternatively, just have someone who understands McLaren service and repair perform the occasional inspection.

Water Pump Replacement

This is a long job because you have to drain the whole cooling system and then refill it afterwards. Given the time and work involved it’s a good idea to replace hose clamps at the same time to avoid any problems from those in the future.

With the car in the air the covers are removed to get access to the pump. Hoses are disconnected and the pump unbolted from the engine and lowered down. Installation of the new pump is the reverse procedure, but be aware it’s harder than it sounds here because there’s limited space to work in.

After refilling and bleeding the cooling system it’s important to get the engine up to temperature and verify there are no leaks. Then the covers can go back on and the car is ready to be enjoyed once more.

Trust Your McLaren to EurAuto.

The McLaren MP4 – 12C is a beautiful car, and compared to some exotics, relatively robust and reliable. It still needs TLC though, and that’s where we come in. We specialize in service and repair of European vehicles and we have experience with the 12C. Call us on (214) 255-3867 to discuss how we can help care for yours.