cagotzmann

Has anyone tried this to get the last bit of air out of the master cylinder.

I bleed my brakes after each track day. So I always try to find better ways to remove all the fluid and air. I pressure bleed all the calipers which requires me to be careful not to let the reservoir go dry. But if it did what would I do. Of course I would be way to lazy to bench bleed the master cylinder so what would be the next best thing to do. After a search on the web this is the most common thing I found.

1. lift the back of the car until the rear of the master cylinder is higher than the front of the master cylinder. Using a level have the bubble towards the rear as shown below.




What does this do. It allows all the air in the cylinder to be trapped against the MC piston seal. When you press the brake pedal the air will be pushed out the bleed hole in the MC. Now it may take a few minutes of slowly pushing all the air out, but it seems to work well.

Here is what it looks like bleeding the MC while still in the car. You can see you need to lift the back very high to get the correct level at the MC.




Here is the video where I found this method. It may be worth a try for those people having a problem getting a firm brake pedal after trying everything.

Also once you lower the car again press the pedal slowly a few times and you will get some more air released if trapped by the MC piston.

Part 1
Part 2

Street Rat

I've used more than my share of brake fluid on my C3. The brake system always works good for a while and then my prop valve light will come on. I want to make sure that I get all of the air out the system next time that I bleed brakes. I appreciate the post. I'll be doing this next time around.

OMF

This should be a sticky......

croaker

I’ll be using this method many thanks.👍👍

mrvette

I live in a hillside, with a sloped driveway, so to block the front wheels and jack it less......

being lazy and all.....

grady white

would parking on a slight incline help

sci85

I've done this myself (lifting the rear) but then i take my larger rubber mallet and bang the MC on the side firmly over and over again until no more bubbles come out of the bleed hole. Then let the rear down and do it again. Drive it around the block then rinse and repeat until no more bubbles. Has worked well for me. Note that sometimes I have to bang on the MC quite a bit to get the last little bit or air out but eventually you'll jiggle the last bit out. Good luck!

cagotzmann

You still need to check the angle at the MC, Put a level at the MC and see if the incline is enough.

As you can see in my picture the amount I lift the rear is just enough to get the correct angle. Any less the air doesn't get moved in front of the bleed holes.

kodpkd

Tilting the MC will get the air out of the MC, BUT you still have the calipers at the wheels to do. The fronts are easy, just use a Motive pressure bleeder at the MC. The rears, not so easy, they also need to be tilted. These need to be tilted with the nose UP and use the Motive. It really works.
The rears are installed almost horizontal, they need to be tilted so the air gets to the bleeder screws.
You will save gallons of fluid.