Need help with brake flush

Messages
681
Location
New Jersey
Earlier today, I attempted to do a brake fluid flush on my `08 Saturn Aura (mechanically, think Chevrolet Malabu). I was using a manual pumped pressure flush tank with the GM fitting for the "tank" mounted on the master cylinder. I pumped the brake flush tank up to a max of ~12 PSI (no more than 20 PSI max is recommended) and bled the back two calipers and then noticed a good bit of leakage under the car below the master cylinder area. My question is why was it leaking where the tank is fitted/mounted to the top of the master cylinder? It was not leaking at the fitting to the top of the tank. Is a hold down strap or something similar required to prevent leaks where the tank and the master cylinder attach to each other? I must be missing a procedure somewhere!?
 
Messages
19,528
Location
Lake Forest, CA
I had a leak at the contact of the tank and the master cylinder on the E430 too when I used the Motive power-bleeder. I sold it and use a fluid extractor(mine is Mityvac), no more leaky problem and bleeding the brake is now less than 10 minutes. The time I spend to raise the car to remove and re-install the wheels is much longer than bleeding the brake with Mityvac. The advantages of a fluid extractor is, it can do many jobs such as changing oil, ATF, PSF, coolant in reservoir and brake fluid. But it could not do coffee or wash the car !
 
Messages
4,021
Location
New England
It's funny - I just finished bleeding brakes with a vaccuum pump and lamented that I didn't have the correct adapter to pressure bleed.
 

SaturnIonVue

Thread starter
Messages
681
Location
New Jersey
Thanks HTSS. Motive is the brand device I used. I would sure like to hear more about your Mityvac too. Model number or your recommendation if models have changed would be very welcome.
 
Messages
977
Location
Fernandina Beach FL
Last edited:
Messages
19,528
Location
Lake Forest, CA
I had Mityvac 7201 for 8 years now. I used it to change oil in the MB E430, then do ATF, PSF, brake fluid ... It was less than $60 8 years ago, it's $82 at Amazon now. It's both extractor and dispenser in one package. I can do oil change in the E430 and transfer old oil into a large container for recycle without a drop of oil on the floor. Of all the tools I have, it's one the best useful tool and it paid for itself after a couple years of uses. Think about it for a while, if you do maintaining your car(s) by yourself most of the times, then $8x is money well spend. If you only acasionally do the maintenance then it may be too costly.
 
Messages
19,528
Location
Lake Forest, CA
<span style="font-size: 14pt">WARNING</span>: Don't waste money buying "Mityvac 7205 Fluid Evacuator Brake Bleeding Accessory Kit". You don't need it to bleed your brakes, just use standard bleeder hose that you can buy from auto parts stores or hardware stores for around $0.50 a foot, all you need is a foot to connect one end to the bleeder screw and the other end to the Mityvac main tube via the black connector.
 
Messages
19,479
Location
Chicago Area
the leak probably was the reservoir to the master cylinder seals. Brake fluid and paint don't get along well! Flush with plenty of water on surfaces that you want to retain paint! I like a vacuum bleeder - less complication.
 
Messages
503
Location
McLean, Va.
I do alot of flushes at work some times they leak at M/cyl cap if not scuare and tight no big deal at all. Glad to see you care enough to do a brake fluid change. The vacume type bleeders are fine BUT all brake companies tell to take it easy on the level of vacume. slight vacume is used to avoid pulling air or dirt in the system because the seals in this system are made for pressure not vacume
 
Messages
503
Location
McLean, Va.
I have been told by brake companies stroking master cylinders is frowned apon because you stroke the seals in to an area where they may have dirt and such resting in the bore and may damage seals that normally don't touch that stuff. They even tell you when pumping pads back out to use short strokes for the same reason. You can also gravity bleed the system if you are working alone. just turn up a bottle on the master cylinder and open bleeders and watch it run. quart bottles work faster than pint bottles due to head pressure.
 
Messages
77
Location
Nevada City, CA
Originally Posted By: vssjim
I have been told by brake companies stroking master cylinders is frowned apon because you stroke the seals in to an area where they may have dirt and such resting in the bore and may damage seals that normally don't touch that stuff. They even tell you when pumping pads back out to use short strokes for the same reason. ........
That's some really good advice you will never hear from someone who later wants to sell you a new master cylinder or rebuild kit. ....Never push the pedal down farther than the normal travel when using your brakes.
 
Messages
11,656
Location
NorthEast
Quote:
just turn up a bottle on the master cylinder and open bleeders and watch it run. quart bottles work faster than pint bottles due to head pressure.
Explain this please. How do you prevent the brake fluid from getting straight to the ground? - Vikas
 
Messages
77
Location
Nevada City, CA
Originally Posted By: Vikas
Explain this please. How do you prevent the brake fluid from getting straight to the ground?
I've never done this, but it would be the same principle that keeps the water in the upside-down 5 gallon jug on the water cooler. ...Until the fluid level drops lower than the neck of the bottle and allows air to enter the bottle.
 
Messages
16,005
Location
NE,Ohio
Originally Posted By: vssjim
I have been told by brake companies stroking master cylinders is frowned apon because you stroke the seals in to an area where they may have dirt and such resting in the bore and may damage seals that normally don't touch that stuff. They even tell you when pumping pads back out to use short strokes for the same reason. You can also gravity bleed the system if you are working alone. just turn up a bottle on the master cylinder and open bleeders and watch it run. quart bottles work faster than pint bottles due to head pressure.
how would a quart bottle work faster.. as fluid comes out.. there is a partial vacuum that would keep the fluid in the bottle until the level is low enough for more fluid to come out(after air goes into bottle)..not seeing where you are getting any head pressure from...
 
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