Install new master cylinder without bleeding?

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Short answer is no, as soon as you remove the old one you will introduce Air into your lines.
 
eekvonzipper said:
Short answer is no, as soon as you remove the old one you will introduce Air into your lines.
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So I will need to bleed all four wheels?
Nice. My cylinder has had the look of being wet for a while. I was told that is normal, now I noticed paint bubbling up below it on the firewall.:mad: So I think it's time for a new one! Just thought I'd throw it out there, i literally just got done bleeding them a few months ago. I dont have a helper, no I have to bribe the wife to come out and help. I'm under the car "hows the pedal feel?" Her: "um, I dont know! You come see!"......... So yep. Fun fun. Well thanks for the bad news! :)
 
I have done it too many times to count. bench bleed master. The new method is to use plugs supplied with master.
crack lines on old master before anything else. Then remove nuts, then lines. Carefully swap the master cylinder,trying not to bump the lines too much. Snug it all up. The air, if any is at the very highest point, a couple slow gentle brake applications will displace air in lines,and when you release pedal fluid will push air upwards into master cyl.
 
I should add, if it doesent work, you have to bleed brakes.
 
Have fluid in the master cylinder, then a few gentle small brake compressions?
Also, what is the right fluid level in these? I think I've been filling it to about 1/4" from the top. Maybe I've been over filling?
 
As mentioned, you must bench bleed the M/C which gets fluid on both sides of the pistons. Plug the line openings while installing. Connect the lines carefully. If you have been careful, the only air in the lines will be at the line fittings. Depress the pedal and hold. Crack open both fittings, then release pedal. 90 percent of the time you will be good. If not, then you will need to bleed all four wheels.
 
Do you "really" want to take the chance of installing a new master cylinder WITHOUT bleeding the brakes? Come on folks, these older cars of ours are not being produced any longer. If you bang it up because of not taking the short amount of time to bleed the system, then you will spend untold amounts of time fixing the car, if it's repairable. I personally would never install a master cylinder without bleeding the system, better safe than sorry.
 
Demonracer said:
Do you "really" want to take the chance of installing a new master cylinder WITHOUT bleeding the brakes? Come on folks, these older cars of ours are not being produced any longer. If you bang it up because of not taking the short amount of time to bleed the system, then you will spend untold amounts of time fixing the car, if it's repairable. I personally would never install a master cylinder without bleeding the system, better safe than sorry.
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This is something i have done hundreds of times. That one little bubble will work itself out. You would know immediately if its not right.
 
But that "immediately" might be the very first time you have to panic brake the car because of someone else's stupidity. I'm just citing common sense that I take to heart. Each individual has the ability to make their own decisions, right or wrong. I've seen countless cars some repairable, some not that had been involved in accidents. I'm not saying it can't be done but I personally wouldn't do it. A safety director once told me "Accidents are just that, accidents but 90% of accidents can be avoided if one of the parties involved had done something different". This isn't a rant, & I mean no harm or slight to anyone, I'm just stating my thought & opinion.
 
If you really want to get into this, i do believe the average person should not be tampering with their brakes at all. Brakes should be left to professionals certified to repair them.
I am a red seal automotive technician,i have done this very thing repeatedly over 30 years. Never have i ever put any of my customers at risk due to a brake failure. Never. This particular procedure was taught to me by an even more experienced mechanic back when i was learning. Im sure if it isnt right the op wouldnt even back out of the driveway.

certified brake products had a disclaimer stating for warranty their products need to be installed by a qualified mechanic.
 
Tooljunkie said:
If you really want to get into this, i do believe the average person should not be tampering with their brakes at all. Brakes should be left to professionals certified to repair them.
I am a red seal automotive technician,i have done this very thing repeatedly over 30 years. Never have i ever put any of my customers at risk due to a brake failure. Never. This particular procedure was taught to me by an even more experienced mechanic back when i was learning. Im sure if it isnt right the op wouldnt even back out of the driveway.

certified brake products had a disclaimer stating for warranty their products need to be installed by a qualified mechanic.
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thank you for chiming in TJ,

Yes,what This man/member said, and I have done it many time with zero problems to this day.
 
^^^^^ I have done it this way for years. Most times it works great. Once in a while you'll have to bleed the whole system. You'll know right away if you pedal feels like a sponge. So yea, Tooljunkie is correct.
 
Kendog 170 said:
Here's your helper.
Brake Bleeders | Speedway Motors
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And - - more good info and tutorials out there. Bleeding brakes not 'rocket science' but, as implied, there are many wrong ways and very few right ways. Goofy You-Tube vids. not best idea. Decades ago, all we had were printed manuals (such as Haynes, Chilton, Petersen, Clymer etc.) - and the large Mopar books based on specific years. Some of us still have tons of those. If you understand the basic theories behind hydraulics and simple (non-ABS) braking systems, you should be able to bleed with confidence. Umm, brake lines that is - hopefully not the other kind :eek:. It takes one person to bleed, albeit longer, with plenty of 'foot-work'. And, as pointed out, brake fluid loves to eat paint, so put plenty of rags underneath the area you are working on and use only correct flair nut wrenches on the lines.
 
Bench bleed the MS first, install it and then bleed it right where the lines go into the MS. Done. Air goes UP, not down, so all the air will be right there at the ends of the lines going into the MS.
 
You guys might not believe this, but I have never heard of bench bleeding. That's why I didnt want to bleed the system again, TONS of air to get out. I wondered if something like that was possible just sitting here thinking, but now I'm happy to hear it is possible! Thanks everyone! I will give that a shot, and if it doesnt give me the pedal, I will go ahead and bleed the whole system. But, with bench bleeding first, the air will be very minimal!
 
Heres common practice for you all. Out of a current chrysler manual
BB513BD0-F9EE-45CB-B54D-ECA4E892509B.jpeg
”Drops Mic and walks out of building”...
 
used to chuck it up in the bench vise and use a screwdriver to push the piston in and out with brake line stubs looped up and into the soup. fill to full and start pumping slowly, it may percolate up so dont put your face down there. keep back filling and pumping until the flow runs bubble free. then you can carefully remove the fittings and attach your old ones. Gently push on pedal a few times and the top bubble should work its way out the MC. Youll know when you got the hard pedal. Todays MC's have plastic plugs supplied that somehow 'do' this.....? DOT-5 doesn't eat paint but may not be 100% compatible with OLD brake seals.
 
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