This is my first time bleeding brakes on my 1988 240.

The Bentley manual I'm following says to keep the fluid level in the reservoir above the min. line at all times, or you have to start again. The reservoir appears to have two chambers, front and rear. I started by filling the reservoir, and the fluid rose to the max. line in both chambers.

While I was doing the first caliper (left rear), however, the fluid level in the rear chamber dropped below the min. line, but the level in the front chamber is still at max. When I add more fluid, the level in the front chamber rises, but nothing happens to the level in the rear chamber.

What am I doing wrong?

 

My 1st question is why are you bleeding the brakes. If it is because of normal maint. then no problem. Also you start with the rear pass. side , then the rear driver side , then the front pass. side and finally the front driver side. I usually buy a different color brake fluid like blue or yellow or red. I use a turkey baster and suck out as much fluid in the MC reservoir and refill with the new stuff. Now you can either have someone pump the peddle while you crack the bleeder valves or you can use a vacuum bleeder or you can replace the bleeder nipples with a "speed bleeder" nipple which allows you to do a 1 man operation. The reservoir should share the fluid for part of the way and then hold different level front and back circuit. If you keep filling the tank it should fill both front and rear. As you might guess when you bleed the system and start to see the different color fluid you know the system is clean. Try it again and see how you do.

 

Bleeding the brakes because some air got in the lines, because I let the fluid level get too low--probably there is a leak somewhere. Mechanic says probably the master cylinder is bad. We shall see.

Using a different color fluid is a very good idea. Didn't know they were available.

One question, though: The Bentley manual says that you start on the "left rear." I assumed that that means "left when sitting in the car facing forward," which would be the driver not passenger side, no?

Thanks a lot for the information,
chasred

 

I'm thinking you might want to fix the problem before you bleed the brakes. Look on the inside of all your tires for oil stains. It should be fairly easy to see where your fluid is leaking.

Anyway, there are several ways to bleed brake lines. The easiest way is to have one person in the car, and one person under the car. Start with the rear passenger brake (farthest from master cylinder), then rear driver's brake, then front passenger, then front driver's brake (closest to mc).

Open the bleeder, have your helper depress the brake pedal & hold it, close the bleeder & have your helper let up on the pedal. Repeat until no more air bubbles come out of the bleeder.

Always keep your reservoir full.


Good luck!

 

X2 There is not point in bleeding your brakes if you suspect that you have a leak.