Last weekend I did an E46 M3 brake fluid change on my 2006 M3. Craftsman Auto Care, a long-time friend of the CCA National Chapter, invited us into their Ashburn location. It was the first DIY event in a while, mainly because the club organizers were traveling a lot in the summer.
Changing the brake fluid isn’t hard, but it requires a pressure pump and can be messy. Like most jobs it’s much easier with a lift. Brake fluid is hygroscopic, meaning it absorbs water through the air over time. This makes it a job to do based on time, rather than miles driven. Enthusiasts would say every two years, you can probably safely go three. Of course, millions of drivers never change the fluid, which eventually leads to longer stopping distances, damage to brake lines, and potentially failure of the master cylinder.
My car needed a change since the last one was in late 2021. Kind of embarrassing for an enthusiast owner. Maybe the pandemic messed with my perception of time passing. I’ll go with that excuse for now and keep better records of routine maintenance requirements.
As you can see from the main image, this job is made easier by the use of a vacuum pump. A popular choice is made by a company called Motive. Using the pump eliminates the need for another person in the car to pump the brake to build pressure, the even “older-school” way of doing a fluid change. The pump attaches to the brake fluid reservoir, and you pump between 15 and 20 pounds.
Once you remove the wheels, you can easily access a 9mm screw at the back of the brakes. The fluid catch bottle has a rubber nipple that fits over this screw and catches the old fluid. Doing this before you loosen the screw saves a lot of mess. You work your way around the car, farthest from the reservoir to closest – rear passenger, driver passenger, passenger front, and then driver front. Once you have roughly a liter of fluid, you’re done.
An added benefit of working on your car is that you notice things. When I removed the rear passenger tire, I got a nasty surprise – what looked like a razor blade stuck in the tread. I had no idea how long it had been there. The tires were not due for replacement, and I’d have to buy two rears since you don’t want one worn and one brand new.
Craftsman helped me spray water on the spot, and there was no air escaping. I was tempted to pull the metal out, but if I then had a flat, I was an hour from home driving on my donut spare. I made it home without incident and pulled the tire off in my driveway.
I got lucky. When I pulled the metal out there was very little beneath the surface. The tire was not punctured. No need for two new rear tires, which is a relief since my E39 M5 needs two rears due to wear. Maintaining M cars gets expensive, so I’m glad I dodged that bullet.
Some pictures below. Happy Halloween!
