hitreason Posted November 16, 2005 Share Posted November 16, 2005 Well, I'm finally tired of driving around with just my ebrake and decided to replace the master cylinder. After reading the rather vague Chilton manual, I have a few questions before proceeding. First off, the manual says that if the brake system is bled with the engine OFF then the vacuum booster can be damaged. Well, I am guilty as charged here. I replaced all the front brake components about a year ago, and bled the brakes without the engine running. So. . . Should I replaced the booster while I'm in there, or is the Chilton manual full of it? My original symptom is no pedal pressure. The loss of pedal pressure was gradual over about 5000 miles. The car does not lose fluid and the cylinder/booster area audibly sloshes and queeffs when the pedal is pushed. Second question: how do I properly bench bleed the master cylinder? Also, any other tips for working on the brake system of a 92 Loyale 5Spd 4wd would be appreciated. This site serves as a great reference tool. Thanks to those responsible. Link to comment Share on other sites More sharing options...
Snowman Posted November 16, 2005 Share Posted November 16, 2005 Chilton's is full of crap. You NEVER, EVER bleed the brakes with the engine running. Relatively gentle pedal pressure is all you need, and anything above that should not be used. Sounds like you need to bleed the system from the master cylinder back. You can bleed the master cylinder just like the calipers. Have your assistant pump up the pedal and hold it, then crack open a fitting on the master cylinder, wait a few seconds, then close it and repeat until no air bubbles come out. Do this for all the fittings on the master cylinder, then do the same thing on the hill holder valve if your car has one. Finally, bleed the calipers as per the sequence in the manual. If this doesn't cure your problem, something else is wrong. Hope this helps. Link to comment Share on other sites More sharing options...
WoodsWagon Posted November 17, 2005 Share Posted November 17, 2005 If you hear sloshing, I'd say that the rear seal on the master has blown and filled up the booster with brake fluid. Take off teh vacuum hose from the booster and see if it is wet inside with brake fluid. Link to comment Share on other sites More sharing options...
nipper Posted November 17, 2005 Share Posted November 17, 2005 TO test a brake booster... with the engine off, pump the brake pedal about 10 times to get all the vaccum out of the booster. With your foot on the brake pedal, start the car. The brake pedal should go down. If it doesnt you need a booster. A booster failure can mimic a master cylinder failure. Personally with the age of the car, i would replace the master cylinder and the booster if you have the funds, since you will have everything apart anyway. nipper Link to comment Share on other sites More sharing options...
hitreason Posted November 17, 2005 Author Share Posted November 17, 2005 Yeah, I'm pretty sure the booster is full of brake fluid. Ever once in a while when I drive my car down a certain hill and then turn I get a sputter and miss and then I smell foule exhaust. Behind me a cloud of noxious white gas blows out my tailpipe for a second. Once the car is level, the fluid sloshes back and driving returns to normal. Apparently the brake fluid level must be pretty full in the booster because its sloshing back into the upper manifold through the vacuum line. So. Should I call the thing shot too? Or is a long time bath in brake fluid a preservative for the booster's innards. Or does the fluid degrade seals and rubber? Guess I'll get a quote from the car parts store today for a booster. The reman. master cylinder was a flat 50. Thanks for the replys Link to comment Share on other sites More sharing options...
hitreason Posted November 18, 2005 Author Share Posted November 18, 2005 Ouch! 150.00 for a reman. booster. I need to shop around! I am tempted to just drain the booster and install the master cylinder. Suggestions anyone? Link to comment Share on other sites More sharing options...
TomRhere Posted November 18, 2005 Share Posted November 18, 2005 A Reman or new booster would be best. But I have swapped some in from a salvage yard just to get by. I wouldn't pull the one you have now, drain it, and put it back on, but that's just me. The brake fluid shouldn't hurt the rubber diaphram inside the booster any, but I myself, wouldn't trust it. Link to comment Share on other sites More sharing options...
MorganM Posted November 18, 2005 Share Posted November 18, 2005 I have an indepth article I wrote on properly bleeding your hydrolic brake system; to include how to bench bleed your master cylinder. It does not cover installation of a new master cylinder; only the bleeding procces. Send me a PM and I can email it to you. Link to comment Share on other sites More sharing options...
nipper Posted November 18, 2005 Share Posted November 18, 2005 Ouch! 150.00 for a reman. booster. I need to shop around! I am tempted to just drain the booster and install the master cylinder. Suggestions anyone? i did a quick search and assumed the car was 4wd and found this http://replacement.car-stuff.com/parts/carstuff/wizard.jsp?year=1992&make=SU&model=LOY-4WD-001&category=N&part=Brake%20Booster&returnurl=null&dp=true&showdc=true#top 108.00 Search the net ... you can get good prices. nipper Link to comment Share on other sites More sharing options...
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