How to - Bench Bleed a Brake Master Cylinder
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- Опубликовано: 27 июл 2024
- Since my pickup needed a brake master cylinder, I decided to show how to bench bleed one prior to installing it.
Bench bleeding is important when installing a new master cylinder to make sure all air is internally purged from the new master prior to installation. Many times it is nearly impossible to bleed the internal air pockets from a new master cylinder once it has already been installed on a vehicle. 
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Been working on cars since 13 years old, now 48, Your brake master cylinder bleeding tips/instructions was absolutely EXCELLENT as well as very correct in procedure, Thank you . You've shown those out there how it is properly done. Thanks again for your time and post. Take care.
No BS, straight and to the point! Excellent video.
Putting a new master and booster assembly on my 78 Trans Am. Figured id see if there was a video out there on it. Yours is real simple and explained very clearly. Thanks for making the video.
78 firebird getting a new master and booster assembly aswell
Good video. Getting ready to change the master cylinder on my old 74 plymouth duster.
this was a good how to, I've changed ABS accumulators without bench bleeding, bleeding on the truck took a while to say the least
Good job explaining it sir. 😎👍 No extra bs to figure out. Straight to the point and explained where it's easy to understand! Thanks!
Thankyou ive finally know what im doing wrong now
Last step to engineer my car here in australia now i can complete it
About to swap the master cylinder in my woman's truck. This was a great refresh. Thanks man
Thanks! I had no idea how to do this procedure.
I don't understand why you didn't rebuild the motor while you had the master cylinder out?!
Haha, good video, thanks!
excellent and thorough video,thanks for taking the time to post it!!!
His to bench bleed
Now that is an excellent explanation! Thank you!
The brake pedal on my 2001 Chevy Prizm is just starting to feel spongy. I'm thinking I should buy the parts before it fails. I'm also thinking I'll spray the bleeder valves with PB Blaster, wait a few hours then try to budge them loose. Just a tiny bit, so air doesn't get into the brake lines. Then I'll be ready when I replace the master cylinder.
Thanks for posting. Had heard description, but can't beat pictures.
Thanks for the help man, simple and effective
Very good video and explanation. Thank you for posting!
Great video man. That helped a lot. Thanks for posting this
Thanks for the video. Note that Cardone Select sells a "fancy" syringe style bleeder for $15. So there's no plug and tube kit included with their master cylinder.
Very easy video my friend... read the instructions in the Chilton manual and I thought I was reading Spanish lol
This method works really well, thank you ,no stress.
I put new master on and fill it up to the top. Then use mighty vac to bleed the lines. Hitting the pedal a few times half way through each brake bleed. Always wear gloves so your not soaking up all the automotive fluids, and brakes are serious repairs best left to someone knowledgeable and skilled.
good video did this in class the other day
Thanks for the explanation!
On a 409 casting with 2 bleeder valves like on my worn MC from my 70 Z28, the full travel is 1.5”. Those of you who have 2 bleeders on the MC, these need to be bled first while on the car one at a time before you start at the furthest wheel away from the MC. There is controversy over the sequence in some shop manuals where some will say to start at the closest wheel from the MC but I always start at the furthest.
excellent explanation
i think it depends on the angle the MC is located. if it points up then the front could have air trapped in it which will never bleed out in the vehicle. either bench bleed or try to raise the back of the vehicle to help release trapped air from the front of the MC.
Very thorough, thank you.
Well made video thank you so much
I seen a video of a guy using a syringe to bench bleed the master cylinder. Looks much easier than using hoses.
Hi great video, it's helped me thanks. One question, did you install the rubber boot? If so, which way does it install and is it better to have it or not?
Thanks for the video
The last two videos I watched on this topic said to finger tight the mounting bolts and THEN screw in the hose lines because you many need that slight wobble to get the threads on the brake lines to line up into the unit. When they're screwed in, then finish tightening the MC down to the brake booster. Sounds like a good tip to me....(just saying).
Well done.
Getting ready to change cylinder and booster In my 1975 mustang
good video bro thanks
Thanks still learning.
Some vehicles it's almost impossible to start the hard lines with the MC bolted on place. leave it loose and get the lines on, then tighten the MC mounting nuts.
halleffect1
Volume is very quiet, if you use a compression filter on the audio it will raise the levels and make it easier to hear
Good video. Thank u
When doing this is it normal for the MC to introduce new air if the Piston is pushed in too rapidly?
You should only go in between 3/4” to 1” max. This is what’s in my instructions when you buy from Napa.
Hey there,i have done this many times but Ive always wondered, how come it cant be done while in the car? like having it setup identical to this and have a friend slowly depress the brake pedal,usually when they are in the car they are nice and level,(at least in my car) just wondering..
good job
I just did a brake job yesterday and when pushing the pedal down I felt it suddenly give an get soft. I looked outside and there was fluid all over the place, coming from the master cylinder. It appears I'll need to do this. Thanks for the vid.
thanks...good video
Well done
Hi! Excelent video!
One question, the outputs which holds the master cylinder are direrente size? .... Greetings !!!
j charles Sometimes they are the same, sometimes they are different. Depends on the vehicle.
Thanks man
hello thank you for the tutorial you can find out where to buy the tools for serving. tank you
Is the pressure the same on both line outs?
cool video…no b.s and straight to the point--im having huge problems getting air out of my 69Mopar. The people who owned it before me put an after market Master Cylinder that had two mounting holes. they used an adapter plate to cover the original four hole factory setup. initially I thought it was the master cylinder, bought a new one, bench bled it. changed the offset booster and still had a spongy pedal. I then made an adjustable pushrod to compensate for the 1" adapter plate. Now the brakes lock on as soon as I apply them. Had to release hydraulic pressure from bleeder valve on the offset booster to roll car back into garage…not sure whats next.
To AE LEILUA
You don't know how to bleed breaks, that is funny;)))
Stfu and offer ADVICE, got enough know it alls already.
and you don't know how to spell BRAKES, that is funny ;))))
How many times did you have to pump before it there was no air?
Looks like it'd be just as easy to bleed it on the vehicle? I'll be doing a master cylinder this weekened.
I would fill those caps with brake fluid so when they go on they're not putting a small amount of air back into it.
Best to bleed it on the car just push the brake pedal i done tons this way works like a charm
Can you give me info on how to do it on the car
Can I bench bleed the master cylinder with the booster still attached? That's the way if came when I purchased it
Changed my tandem mc without doing this seems to work ok?
Couldn't you put it in the truck an bleed it that way an then hook up the lines . I need to replace my hoses an rear wheel cylinders anyways
When you connect that MC to completely empty brake lines, I would assume the brake fluid starts flowing into the lines, with the air in the lines going the other way, ending up in the MC, and you're back to square one?
No the brake fluid would force the air down into all the lines and out the bleeder
Thanks
Great vid, but, where did you get your bleed kit from please ???? thank you....
Usually comes with the master cylinder when you buy it.
Fuel Injection Sucks were do you order the master cylinder
How do you know if you blew the seal in the back is blown i bench blead mine at my job i forgot not to go all the way till it stops i didnt see anything
The master cylinder on my C10 has bleed screws built into it, is it possible to do this technique using the bleed screws while the master cylinder is still bolted on to the booster?
+andymcdo I've seen these, but never messed with one. In theory, you should be able to. I think it's more designed to bleed the air between the master and the lines when you put a new master on, so you don't have to bleed the whole system.
i did this and i didnt have to bleed my brakes, good pedal i think thats wierd i figured i would need to bleed them for sure
I just bench bled a master cylinder for my 76 jimmy and I noticed that the larger of the two things that hold break fluid was more responsive. As in-the break fluid would come out of that one first and more rapidly then the smaller one would follow after the cylinder being depressed about half way. Is that normal or do I need a new master?
Thats normal. Modern master cylinders have a 2-stage piston design.
To call it "painted" is to use the term loosely.
How to bench fluid brakes for motor
I am working on a friends 2003 Chevy Trailblazer with 4.2 vortec motor. I replaced the front rotors and pads. In doing that I realized the passenger side caliper was bad and leaking fluid all over. I replaced it and went to bleed all the brakes several times. The brake pedal never got better and there was no fluid going to the passenger side brake line and very little to the drivers side. I disconnected the brake hose from the line and no fluid coming out when pushing on the brakes. I traced problem to bad master cylinder with a used one from reliable used parts place. I went to bleed the brakes again and still no fluid going to the front. I did some research online and found that the abs system could have got air into it because the caliper was leaking before and the master cylinder fluid was gone when I first got the truck.
My main question is, the bad caliper was leaking out brake fluid and no fluid goes to that caliper. What would cause that? I am figuring now I have to replace brake lines, bleed the abs and maybe bench bleed the master cylinder. Just was curious.
The ABS pump will not bleed on many GM's unless it's put into a "bleed mode" using a scanner. I've tricked them a few times by bleeding with the key on, but it's not a guaranteed fix. Your ABS unit may also be acting as a proportioning valve, restricting fluid to a supposed "leak" in the system, not sure how they are set up.
+Fuel Injection Sucks can i mity vac calipers on my 07 escalade well enough to get to a dealership for an abs bleed? (10 miles away 3 miles of heavy stop and go)
Just curious why you can't just run the bleeding hoses and bleed while the MC is already installed? Why does it have to be out of the car?
Time - it only take a couple minutes to do it off the car. If you install it dry, it will bleed fine but you'll be pumping for a while (and waste more fluid $)
Question for ya, im installin BMC from Silverado 1500 '02, into '01 Mid size Blazer, how can i know which connection goes to rear\front brakes?
Usually the larger chamber goes to the front.
Its tricky- because the rear brakes pipe (coming from BMC) is 1\4 inch in diameter with bigger nut and front is even thinner with smaller nut, and i can see that thin pipe goes to front brakes thru the ABS, and on new BMC the thread on both channels are similar, i just installed it the same way as it was before- rear brakes to front part of BMC and front ones to the bigger part of the BMC.
And now it seems that the rear brakes much stronger then it was with the OEM Master, truck literally slows down without jumps\kicks on the tail ( bore is 1\2 inch more then OEM ) since im using 275\55\R17 from Corvette i cant really feel the tires in so called overbraking way, its just stops quicker with less pressure on pedal... so weird...
OEM calipers, vacuum booster, ABS.
Could be the difference in bore size and stroke of the master. The one from the Silverado surely displaces more fluid.
It was air, and probably the same amount in both parts of master, because the brake light never came...
right now is so nice with the new BMC, twice less travel so i can lover the brake pedal and make it even with throttle pedal.
1999 Dodge Durango. I put a new master cylinder on today Unsuccessful. It won't stop I am going to have to bleed with master cylinder on the vehicle. When I bled the rear nothing came out. Most the fluid came out of the left front. I guess I will start again but the master cylinder is on the car.
Wait, if the seal is brittle because it's been on a shelf for years, wouldn't I want to figure that out and not use it if it is?
That's why it's good to rebuild a master cylinder rather than get a new one. That's all a rebuild kit is. New O-rings, New seals.
So whats the difference between that and in the vehicle bleeding?
Bench bleeding it first will save you a lot of time trying to force that air all the way through the lines.
DardeeChar
Wrong.. bench bleeding is to save time and not waste it pumping air through the entire system. That's why the tubes he used are the best method there is, as it eliminates all air and it's visible.
You DO NOT want that piston to be pushed all the way to the end as you claim here. That's why they tell you when bench bleeding to only go in about an inch.
The rod doesn't push the piston all the way in while in the car for a reason... not to damage and or brake the seals/ o-rings etc. The fluid dynamics in the sustem of the master cylinder are designed to handle air being trapped as you think.
*****
"You DO NOT want that piston to be pushed all the way to the end"
Yeh thats true, I've read where guys floored the pedal only to find it blew the master cyl seals.
I managed to remove the master and bench bled it, very simple, no drama in the end.
***** Gotcha! :D
BEWARE. I could not press in cylinder myself so I sucked the line and drank the fluid. I spent 4 days in hospital because of the fluid.
as they say, spitters are quitters.
Anyone else find this channel by seeing the name of channel and just falling in love with it lol
If after installing master cylinder, have no brake pedal.
So I can do this without the two small hoses leading back into the cylinder?
Yes, you just have to plug both outlets.
Thanks, just got mine installed on a 64 c10 thanks for the video man
how do you call that Tools please reply? how much?
Bleeder Kit
Might be good to point out to folks watching that brake fluid is toxic, and you should wear chemical resistant gloves...
Oh Gawwwd yes, maybe even have OSHA come out and verify the procedure and a HAZMAT crew to do a clean up. Gimme a break.
Dump the old brake fluid on a stump
It will be fine because as you can see he had dookie on his fingers from fiddling with his ass before the brake job!
Hope that tailgate you're working on isn't painted. Else it isn't now.
They do not come with bleeder kits anymore!
Mine did 7/2018
I bought a bench bleed kit off Amazon and it came with black hoses WTF? chinese so I went to Ace bought some clear hoses
Master cylinder can you say that boys and girls.
No volume
Put it on vehicle first so you know it fits ( fittings, pushrods depth etc.) too many instructional videos on you tube skip this very important step. In fact if you have pressure bleeder available bench bleeding is a complete waste of time. 43 years.
Yeah. Pressure bleeding rules.
I think you want the hoses submerged in the fluid, don't you?
Yes.
en français plyz
Fix your audio.
yet another useless video and skipping the most important part bleeding the cylinder in car.
That's not bench bleeding. Look up videos on how to bleed brakes for that. "Bench bleeding" refers to bleeding it on a bench, IE, not on the car.