The topic of this text, brake fluid, isn’t as sorely uncared for as differential gear oil or energy steering fluid. Brakes will finally command the eye of even probably the most inattentive proprietor. However we ought to be listening to our brake system lengthy earlier than it screams at us.
Mercedes is among the few automobile producers to prescribe a service interval for brake fluid — two years. And there are excellent causes for this. First, brake fluid is extremely hygroscopic, readily absorbing water vapor from the environment. If you happen to depart a container of brake fluid open in a single day, it will likely be fatally compromised by the subsequent day. Water within the fluid can boil and vaporize when the brakes are utilized, stopping the transmission of strain from the grasp cylinder to the caliper. The seriousness of that security hazard needn’t be acknowledged. Water additionally causes corrosion inside the brake system. Lastly, the fluid inside the caliper is subjected to very excessive temperatures and degrades over time. The fluid within the reservoir would possibly look alright, however there isn’t a recirculation of fluid on this system to supply a visible cue to intervene.
If you happen to dwell in a damp local weather, Mercedes’ prescription may very well not be sturdy sufficient. It could be crucial to alter the fluid yearly. And it’s best to do that within the driest a part of the 12 months. For most individuals, the job is finest achieved within the spring, however in swampy Central Florida, for instance, one of the best time to work on brakes is the winter, which is the dry season. Regardless, common work on the brakes gives extra alternatives to examine the situation of the pads, rotors, and versatile brake traces. The opening and shutting of the bleeder screws prevents them from changing into frozen in place by rust. And your caliper seals with love you for it.
Whereas some nonetheless swear by the standard, two-man brake-bleeding process, energy bleeders are splendidly efficient and make brake bleeding a easy, one-man operation. Energy bleeders eradicate the necessity to continually monitor the fluid stage within the reservoir, thereby lowering the chance of air getting into the system and requiring us to start out yet again. They usually have been demonstrated to scale back the chance of harm to the grasp cylinder throughout conventional bleeding.
The usual recommendation to start out with the caliper furthest from the grasp cylinder holds true. Actually, that proper rear caliper appears to be by far the toughest to bleed fully. It’s crucial to maintain going till the fluid leaving the caliper is fully clear and freed from bubbles. A small quantity of Teflon tape wrapped across the threads of the bleeder screw can safeguard in opposition to any tendency for false air to be sucked in at that time. Whereas such air doesn’t stay within the caliper to trigger operational issues, it does make it tough to inform when the brakes have been bled efficiently.
DOT four fluid ought to be utilized in Mercedes brake techniques. If all you will get is DOT three, that’s not the tip of the world: it won’t hurt the system in any approach; it merely has a decrease boiling level. No matter you do, don’t use DOT 5 brake fluid; that is designed solely for racing functions and doesn’t belong in street autos.