The following article gives detailed instructions on performing a brake flush on a BMW E36 3 series car. Even though we have used a 1996 BMW M3 to perform this procedure, this article can be applied to any 1990-1998 BMW E36 vehicle with minor modifications.
A BMW E36 brake flush is recommended every 24 months to keep your lines and calipers free from corrosion and your brakes operating properly.
A brake fluid flush is pretty important maintenance.
We thought about that statement for quite a while before writing it and yes, we have grossly understated the obvious; a brake fluid flush is not pretty important, it’s extremely important. But we think it is a good general representation of how many of us perceive our BMW brake systems…that they are well engineered, low maintenance mechanisms that only need attention every few years. Nothing could be further from the truth.
Brake fluid is hygroscopic. Like the cellulose fibers of a cotton ball a car’s brake fluid will absorb water, wreaking havoc to metal brake lines, fittings, and caliper parts. Water in a car’s brake system will also lower the boiling point of the brake fluid, causing a substantial decrease in braking power when the calipers heat up. And you don’t have to be doing laps on the track to become a victim of a “spongy” brake pedal…daily city driving can cause significant heat to build up in the brake fluid as well.
If never maintained, a car’s brake system will eventually fail with potentially catastrophic consequences. Brake lines and calipers become corroded with age and neglect. The Repair Guide recommends conducting a BMW E36 brake fluid flush every 24 months whether the car is driven or not. It is cheap insurance against having to replace expensive parts as your car gets older.
There are several ways to do a brake fluid flush on your BMW E36, but we highly recommend using a brake bleeder pump. It is extremely simple to use, and you can do the job by yourself (no brake pedal pumper needed). If you do not want to purchase a brake power bleeder kit, there are many other articles on the web that give instructions on alternative methods, such as vacuum bleeding and the “two person” method.
A brake power bleeder is a plastic bottle that you pressurize with a pump handle, just like an ordinary poly spray bottle you would have out in the garage to spray your yard for bugs. The only difference is the power bleeder has a pressure gauge and a special fitting that screws onto the top of your brake fluid reservoir. When you fill the power bleeder with brake fluid and pressurize the bottle (we recommend 20lbs), you have a continuous supply of fresh brake fluid being forced through your lines and out of the caliper bleed screw. The catch bottle that is also included in the kit is attached to the bleed screw with a slip on rubber fitting and retains the fluid being forced out of the system. It has convenient lines embossed on it so you know the quantity that has been flushed out of your calipers.
**Brake fluid is extremely caustic to automotive paint. Take extra precaution not to spill any fluid on painted parts of your car. Also make sure to dispose of any rags used to clean up brake fluid so they are not inadvertently used to wipe the finish of your car.
The BMW Repair Guide uses the Motive Power Bleeder Kit on all of their brake fluid flushes. It comes with a catch bottle with a rubber connector that fits snugly over the bleeder screw and eliminates any brake fluid from getting on the floor or the car.
1. Brake fluid (required) – Always use a high performance DOT 4 brake fluid in your BMW E36 3 series car. A typical flush uses about three bottles of fluid. We always suggest buying an extra one to keep in the garage for “topping off” during regular maintenance inspections on your car.
- Jack up car and put on jack stands. Remove all 4 wheels. Not sure how to jack and support your BMW? Read our article on the simple and safest way by clicking here.
- Remove cap from brake fluid reservoir.
- Vacuum out old fluid with a vacuum pump or syringe. Just vacuum out until bottom of plastic reservoir is dry. **DO NOT vacuum fluid out of any hoses leading from bottom of reservoir. This may introduce air into the system.
- Refill reservoir with fresh brake fluid. Do not overfill.
- Pour rest of can of brake fluid into power brake bleeder. Screw power brake bleeder fitting onto top of reservoir and pump tank to 20psi.
Use the following bleeding pattern to properly flush your brake system:
BMW E36 brake flush – bleeding pattern
- Check the power bleeder- it should have plenty of brake fluid in it and the pressure should be at 20psi.
- Starting with the right rear caliper, remove dust cover and place the 7mm open end wrench on the bleeder screw and turn counterclockwise until it breaks free. DO NOT open the screw so fluid comes out. The bleeder screws can sometimes freeze up over time, so the idea here is to just break it free before proceeding to step 3.
- Attach boxed end of 7mm open end wrench to bleeder screw, then attach rubber fitting of catch bottle to nipple of bleeder screw. Turn the screw counterclockwise until fluid begins to fill the bottle.
- While bottle is filling with fluid, continue to check power bleeder to make sure pressure is at 20psi and that there is plenty of fluid in the bottle.
- If at any time during the bleeding process the power bleeder runs low on fluid, STOP. Tighten bleeder screw immediately, add brake fluid to power bleeder, pump to 20 psi, then continue. This is very important so you do not introduce air into the brake system.
- You may have to make several trips back and forth between the power bleeder and the caliper to insure the bottle remains at 20psi and has plenty of fluid.
- When fluid in catch bottle reaches first measurement line (approximately 275ml), turn bleeder screw clockwise and tighten snugly (do not over-tighten).
- Remove catch bottle and replace dust cap on bleeder screw.
- Proceed to next caliper following above instructions.
- After all of the calipers have been bled, remove power bleeder from brake fluid reservoir. Top off fluid in reservoir if needed.
- Replace cap on brake fluid reservoir.
- Replace wheels on car.