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Discussion Starter #1
It's been cold and windy here, less than 20* today. Since my fiance's ranger can't get out of the driveway, she is using my car. So I drove the truck to work today...pucker factor 9! Everytime I touched the brake pedal it sucked to the floor and took a LOT of effort to get it to pull it back up. When I disconnected the vacuum line from the booster, the problem stopped, but then off course, no power assist.

Does this sound like a master cylinder valve problem or a vacuum booster problem?
 

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It sounds like just a booster problem if the problem stopped when you removed the vacuum line. I just replaced the booster in mine this weekend due to a hiss whenever I pressed the brake pedal. It took me just over an hour to do by myself and I don't even qualify as a shade tree mechanic. I paid about $75.00 at O'Reilly's.

The end result, a noticeable but in my case not a major improvement in my brakes and no more hiss.:thumbup
 

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what did it do when the pedal sank did it stop or did it continue to go like you had no brakes when the booster was hooked up

and when you had it un hooked even without the assist did the brakes stop you or just go to the floor
 

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Discussion Starter #4
Definitely stopped. Booster isn't that old, but was a reman. I think that was my problem. Possibly getting some moisture in it and freezing?
 

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Discussion Starter #5
I thought I had it half working in the parking lot at work. Turns out our had just froze in the up position, not sticking to the floor ant longer. On my careful way home I tried to avoid hitting an owl and when I stood on the brake pedal I heard a pop and it seemed like the rod slipped through whatever plunger or seal was suppose to move with it. It started sticking to the floor so bad that when I was trying to slow down to turn into my driveway, I overshot it, missed the trash can and drifted through the yard. If I didn't have my steel tire under the pedal, I would've gotten rearended by jack-off behind me that couldn't get the idea that something was wrong with the hazards and slow speed.

Apparently I did the booster swap so long ago that I bought it from advance auto parts, and they don't keep warrenty records that far back...

Picking one up from the zone later. I suspect that this reman unit was bad from the start. I've had occasional problems with it like this every winter, but only ever the first time I hit the pedal and it was a lot easier to get it to return.
 

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I would see about that warranty for sure. But, when was the last time you changed your Brake fluid? Brake fluid is highly hygroscopic. It absorbs moisture. Every time the cap is off, moisture is let in. Last winter, my clutch line froze and popped. The freezing point of brake fluid is -50F, but that is without contamination.
 

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Unfortunately it sounds like you might have ruined your master cylinder as well. I'm pretty sure that there was moisture in the booster, causing it to not function properly. Now, with what it sounds like, you probably broke the master cylinder as well.
 

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Discussion Starter #8
MC works fine without vacuum boost. I think the snow melting on the hood and leaking down the firewall manned to make it into the back side of the booster and refreeze. Should know by this weekend when I swap in the new reman booster.
 

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Discussion Starter #9
The one I had was from advance auto and they don't share records between stores or even keep records from a few years back on their lifetime warrenty parts. Problem was indeed the booster. The Advance auto reman just had some felt and plastic cover on the rod that allowed moisture in. The reman from AutoZone actually had a sealed rubber boot like an OE booster (used to work for AutoZone as well). Pedal still feels a little spongey, but I suspect that's from having 1 ton rear cylinders and 1/2 ton calipers. Brakes engage a lot smoother than they ever did with the booster from advance auto.
 

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Discussion Starter #10
Used to use then when they moved into town, but since I've moved back to my hometown they have gone way downhill with their service. I only go to then off I have to anymore street they cancelled my installers account and keep giving me pre-used parts.
 

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similar problem

I have a similar problem with my 86. I hear a hissing sound when I hit my breaks and the pedal goes almost to the floor. No real grabbing at all. When I have the vehicle off and pump the brakes to bleed them they stiffened up but once I turn it on I can pump them to no avail. How would I disconnect the booster to check it, just pull the vacuum line off?
 

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Discussion Starter #12
Pull the vacuum line off with the small plastic check valve.
 
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