Live-n-learn......brake flush 101

[Toploader]

So today I made my way to my buds repair shop for a LOF and a brake flush..........well fortunately all the brake bleeders opened up with no trouble.......having not been open in at least 25 years.

Well, he sets up a 16 ft ladder and has one of the younger techs hover over the master cylinder with the car up on the lift.....meanwhile on the ground he hooks up a device that has a rubber front that attaches to the bleeder, and at the other end his air hose is coupled on. As he pulls the trigger I see the brake fluid start to enter the qt plastic holding device......all the while yelling to the tech on top to keep filling the master and not to let it run dry at the bottom. After two full fills in each master cyl chamber, we close the bleeders.

After letting the car down to the floor, I discover I have "no pedal"........ok this time I get into the car, and my bud is under the car yelling out........pump-em-up, then hold it down..........well we did this at all four wheels.......and presto I had a hard pedal......I bet the young kid let one of the parts of the master run dry before re-filling.

So now I have clean fluid that will most likely out live me..........as the old fluid had been in there for over 25 years.

[Mainemantom]

Not good to have old brake fluid. Collects water = corrosion from the inside. How are your rear brake cylinders ? if they are old, I would have them replaced, then re-bleed the brakes. Just my 2 cents.

[EaOutlaw1969]

The industry standard is if you have Dot 3 brake fluid is for it to be flushed out every two years as part of a preventive maintenance program.

Yet you can get anal and get some brake fluid test strips or a electronic tester and test the fluid .

I can count on one hand the number of people in my many years of working on cars the people that followed this strict program.

Even my own cars my brake fluid on new cars that I have owned have been negelected because I knew every 2-3 maybe 4 years I used to get that new car itch so i could care less as my maintenance program was to just get a new car.

When I could not afford a new car in the past and now that I am disabled I am forced to deal with deglected brake systems, I also had to deal with them daily when I worked as a commision mechanic.

As mentioned by Mainemantom brake fluid is hygroscopic meaning it can wick moisture from the air to me this has meant I try and never work on the hydraulic parts of any brake system when the relative humidity is very high or when it is raining. and I never ever use a previously opened brake fluid container.

This being said brakes are important and we cannot control mother nature so whenever I had to service brakes in a monsoon or a hot very humid day I would check and flush the fluid again on a day with lower humidity. ( getting customers to agree to this was not too hard when they just forked over a lot of money for a expensive brake system overhaul )

Like you my new to me MGM has a neglected brake system with very old pitch black Dot 3 brake fluid mine also has a seeping master cylinder.

I know from experiance and from completeing an inspection my brake pads on my 4 wheel disk brakes are in good shape and I have no other leaks, yet I plan on having to replace the master cylinder with brake booster, all the calipers will get overhauled or replaced along with all the rubber lines I will most likley also replace the pads and rotors plus parking brake shoes.

This will take a very long time for me to do with my bad neck and back. yet I know the master cylinder and each caliper will have a accumulation of corrisive sludge built up eating away at the pistons and cylinder bores in each caliper and is what caused the brake master cylinder to leak brake fluid.

I could flush the system like you had done and just replace the master cylinder because it is leaking yet I know for a fact a severly neglected brake system cannot be restored just by flushing the brake fluid because it will still have the old corriosive sludge in the system eating away at your brake parts.

While it was good that you flushed the brake system all you really did is raise the boiling point of the brake fluid to normal levels. ( provided your buddy used new brake fluid from a unopened can ) and did the job on a low humidity day.

I am not suggesting you run out and replace all your brake system parts but I am just letting you know that you are wrong so very wrong about the brake fluid out living you.

If it does I am sorry to hear you are not planning to be around that long.

One other point I may add when bleeding brakes on a neglected system I was taught to never pump up the brakes while bleeding them, I was shown how it is much better to gravity bleed all four wheels then go back and bleed the system with the procedure below to lessen the number of times the seals on the master cylinder piston has to drag across the acumulation of sludge that has built up in the bore.

With a full brake pedal your master cylinder piston only goes down so far so sludge will accumulate in the area not constantly being wiped by the seals, when your pumping up brakes doing a convential bleed the seals will go over this sludge and could damage the already taxed seals or fold the seal over causing the master cylinder to just not work any longer.

When bleeding a old system it is best to gravity bleed the system as I mentioned then starting at the right rear or furthest from the master cylinder open the bleeder then have the assitant slowly push down on the pedal but only 1/2 of the brake pedal stroke close the bleeder release the pedal then repeat until no air is seen coming from the bleeder. do this on all four wheels.

Once done make sure the fluid is topped off and have the helper test the brake pedal it should be rock hard. if it is not you may have to do the same procedure again but this time go all the way to the floor with the pedal, yet you will not have to continue to pump the pedal over and over draging the seals of the master cylinder piston over the sludge as much as you would by convential bleeding.

Pumping up the brakes will bleed brakes but it make the process take longer because the pumping action pushes some air back to the master cylinder each time you release the pedal.

Doing it the way I was taught keeps the air moving in one direction ( out of the system )

[Toploader]

Tom,
Pulled the rear drums to check how much meat the shoes have, plenty still there on the riveted lining, front pads are also good. As to the wheel cyls, all are dry with no weep or leak, and the master is dry as well...I appreciate your input!!

Not good to have old brake fluid. Collects water = corrosion from the inside. How are your rear brake cylinders ? if they are old, I would have them replaced, then re-bleed the brakes. Just my 2 cents.

[Toploader]

Greetings to you in Lake Worth.....used to live in Hollywood during my college days of the late 60's LOL!! I agree with all you said, problem is my bud has a VERY BUSY SHOP (NYC area) and there was just no time to gravity bleed the brakes!! I have brought my cars to him for almost 40 years, and we have many mutual friends in the repair trade......I have no place to work on my car as I live in a NYC apartment, and my spine is full of DDD:-(....He is down to two techs and one new kid as a helper......with a ton of late model car work, so the fact my '86 "boat" is given time (and many times not charged) is greatly appreciated when needed. I know he will just love me next month when I pull my old Studebaker out of storage and schedule a LOF (30 zerks on a Stude front end) and yes.....complete change of DOT 3....at least with the Stude I had all the wheel cyls SS sleeved years back, and have no leak or stop issues.

The industry standard is if you have Dot 3 brake fluid is for it to be flushed out every two years as part of a preventive maintenance program.

Yet you can get anal and get some brake fluid test strips or a electronic tester and test the fluid .

I can count on one hand the number of people in my many years of working on cars the people that followed this strict program.

Even my own cars my brake fluid on new cars that I have owned have been negelected because I knew every 2-3 maybe 4 years I used to get that new car itch so i could care less as my maintenance program was to just get a new car.

When I could not afford a new car in the past and now that I am disabled I am forced to deal with deglected brake systems, I also had to deal with them daily when I worked as a commision mechanic.

As mentioned by Mainemantom brake fluid is hygroscopic meaning it can wick moisture from the air to me this has meant I try and never work on the hydraulic parts of any brake system when the relative humidity is very high or when it is raining. and I never ever use a previously opened brake fluid container.

This being said brakes are important and we cannot control mother nature so whenever I had to service brakes in a monsoon or a hot very humid day I would check and flush the fluid again on a day with lower humidity. ( getting customers to agree to this was not too hard when they just forked over a lot of money for a expensive brake system overhaul )

Like you my new to me MGM has a neglected brake system with very old pitch black Dot 3 brake fluid mine also has a seeping master cylinder.

I know from experiance and from completeing an inspection my brake pads on my 4 wheel disk brakes are in good shape and I have no other leaks, yet I plan on having to replace the master cylinder with brake booster, all the calipers will get overhauled or replaced along with all the rubber lines I will most likley also replace the pads and rotors plus parking brake shoes.

This will take a very long time for me to do with my bad neck and back. yet I know the master cylinder and each caliper will have a accumulation of corrisive sludge built up eating away at the pistons and cylinder bores in each caliper and is what caused the brake master cylinder to leak brake fluid.

I could flush the system like you had done and just replace the master cylinder because it is leaking yet I know for a fact a severly neglected brake system cannot be restored just by flushing the brake fluid because it will still have the old corriosive sludge in the system eating away at your brake parts.

While it was good that you flushed the brake system all you really did is raise the boiling point of the brake fluid to normal levels. ( provided your buddy used new brake fluid from a unopened can ) and did the job on a low humidity day.

I am not suggesting you run out and replace all your brake system parts but I am just letting you know that you are wrong so very wrong about the brake fluid out living you.

If it does I am sorry to hear you are not planning to be around that long.

One other point I may add when bleeding brakes on a neglected system I was taught to never pump up the brakes while bleeding them, I was shown how it is much better to gravity bleed all four wheels then go back and bleed the system with the procedure below to lessen the number of times the seals on the master cylinder piston has to drag across the acumulation of sludge that has built up in the bore.

With a full brake pedal your master cylinder piston only goes down so far so sludge will accumulate in the area not constantly being wiped by the seals, when your pumping up brakes doing a convential bleed the seals will go over this sludge and could damage the already taxed seals or fold the seal over causing the master cylinder to just not work any longer.

When bleeding a old system it is best to gravity bleed the system as I mentioned then starting at the right rear or furthest from the master cylinder open the bleeder then have the assitant slowly push down on the pedal but only 1/2 of the brake pedal stroke close the bleeder release the pedal then repeat until no air is seen coming from the bleeder. do this on all four wheels.

Once done make sure the fluid is topped off and have the helper test the brake pedal it should be rock hard. if it is not you may have to do the same procedure again but this time go all the way to the floor with the pedal, yet you will not have to continue to pump the pedal over and over draging the seals of the master cylinder piston over the sludge as much as you would by convential bleeding.

Pumping up the brakes will bleed brakes but it make the process take longer because the pumping action pushes some air back to the master cylinder each time you release the pedal.

Doing it the way I was taught keeps the air moving in one direction ( out of the system )

[BoulevardRide]

All kind of ways to skin a cat. i use a turkey baster in the mc, swipe it clean with brake fluid, refill with fresh, take it the local shop to bleed from the wheels. for 30 bucks i'd rather let them deal with the dirty end. by cleaning out the master myself, at least i know they're pushing fresh juice thru the lines
On this car i needed some new brake lines anyway so they didn't charge to bleed the rears

[gadget73]

Basically the way I do it, but I bleed them myself. Any time I have to mess with the brakes I swap the juice out of the MC and bleed, even if I don't do all 4 wheels. You have to buy a quantity of fluid anyway every time, so why not flush at least that much old crap out.

[Salty Dog]

Mighty vac makes it pretty easy without a helper. I only had to do it one time on the mgm after I replaced the master cylinder and the booster.


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