I have a new brake booster and master cylinder to install (similar to picture). How do you bench bleed it? Do I need to remove the booster to bleed the master cylinder? Or can I bleed the master cylinder with the booster connected by moving the brake plunger in and out? thanks Nick
I’ve usually taken just the reservoir off and held it in a vise as I actuated the plunger. It also made it less cumbersome when installing everything into the car. Others may have a genius idea; since I’m no genius, I go caveman on virtually everything
It is very easy to remove the master cylinder from the booster, then install the new booster, bench bleed like Joe said, then carefully install the MC on the booster in the car. (MC being level helps make it easier). But if you have someone to assist, you can do it with everything mounted in the car and prior to connecting the lines. (remember to have all the ports except the those used for the "bench bleed" plugged on the MC) I always use a trash bag, cut and laid under booster/MC to protect the inner fender liner and other things from the stoppit juice.
Some master cylinders used to come with a kit. Plastic fittings with clear tubing that screwed into the front and rear ports. Then you just looped the tubes into the reservoirs and activated the master until there were no bubbles in the tubing. Something like this, https://www.amazon.com/Dorman-13911-Master-Cylinder-Bleeder/dp/B001SG8ZC0
Yes, I just bought that same exact kit. Came in yesterday. I just wasn’t sure if I could bench bleed with the booster attached or if I had to separate the booster and master cylinder. I don’t know what to expect if I separate the two.
If you have fluid in the MC, put the cover on and secure the bales, remove the two nuts, break the lines loose at the fittings, and wrap, bag and tape them. The MC will slip off, and you might have a spacer plug (drum vs disc MC have a different plunge so the rod into the piston dimple on the back of the MC is either shallow, or deep, and some have the deep piston and a "spacer" that makes it a shallow. The "spacer" looks like the one below and would go in the piston on the MC on the left to make it similar to the one on the right. So, if your's has that spacer, it might fall out of the MC, due to the tilt as you remove and install the MC. But other than the fluid issue, the removal and installation is only the brake lines, (possible pressure switch wire) and the two nuts securing the MC to the booster, so it's not complex. After the pressure bleed, securing the top cover on the cylinder and not pressing the piston during install, you should not loose more than a few drops of fluid, but make sure you have the fender and such covered with plastic. Just in case.
@TrunkMonkey Cool Thanks! It’s a disc/drum version and it’s not on the car yet. Brand new in box. Sounds like I can take apart (Easily). Mount booster to car. Then bench bleed with the kit. And mount MC to booster. before all the fluid drains out of it
Yes. You won't loose any appreciable amount of fluid. When you do the bench bleed, go slow, make sure the tubes stay submerged, as the fluid will go both ways on the press and return stroke. Just keep going slowly until all the bubbles are clear of the tubes.
I'm not a fan of Cardone but these syringe style fluid pushers make bench bleeding really quick and you don't aerate the fluid like with the little tubes. https://www.amazon.com/Cardone-10-5...=Brake+bleeding+syringe&qid=1595083652&sr=8-4 Had a Corvette style master cylinder that was not cooperating once and this made quick work of it.
