[jzfish]

Hi, First post here although I've learned a lot searching the threads. I purchased a 2003 V6 escape and noticed a vacuum leak coming from behind the brake pedal. It gets louder when accelerating and stops when coasting. Brakes seem to work fine but I'm ready to take it in to be safe. Has anyone had this problem before? If it's an easy fix I would like to do it myself and save some $. Thanks for all the info.

 

[Squishy]

Might be an internal leak in the brake booster. My first thought is to disconnect the brake booster vacuum line and plug it up, then listen for the leak. If the hissing noise disappears, replace the booster.

 

[jas88]

What makes you think it is a vacuum leak? A vacuum leak should be loudest when coasting and quieter when accelerating. Every brake booster leak I have ever heard can only be heard when pressing the brake pedal.

 

[jzfish]

Thanks I'll check the power booster tonight. It sounds like a vacuum leak to me. It is a hissing sound or air leak coming from the rubber seal behind the pedal. It also lets out some air when I turn off the ignition.

 

[Squishy]

If you can't reproduce this in the driveway, do not test it out on a street with traffic. Disconnecting the booster will disable your power brakes (and your parking brake is NOT an emergency brake). To help you stop, downshift through the gears.

 

[jzfish]

Ok looks like it's the power booster. Disconnecting the vacuum line from the power booster stops the leak. I've changed a master cylinder before but never a power booster. I guess I'll give it a try. Thanks again for helping out.

 

[jas88]

It's gonna have 4 studs going thru the firewall so you need to remove those bolts first from under the dash, and disconnect the brake pedal. Then take off the 2 bolts under the hood that attach the master cylinder and just pull the MC away and let it hang by the brake lines. Then you just pull out the old booster and replace it with the new unit. Some new units I have seen come bare metal so if yours is like that you may want to paint it the day before you do the job.

 

[jzfish]

You make this sound easy. Does this mean since no lines are coming off the MC I won't need to bleed the brakes. There is no fluid in the booster? Just works off the engine vacuum? I'm tracking down the booster and it looks like a $125.00 part. I'm sure by me this would be a $500.00 repair at my mechanic. Sure would like to do this myself so my 3 kids could eat this month.

 

[Squishy]

It's not necessary to bleed the brakes. The booster works completely off of vacuum - when the brake pedal is not depressed, engine vacuum is present on both sides of a diaphram. Once the pedal is depressed, an air valve allows atmospheric air to enter the side of the diaphram closer to the firewall, which pushes the diaphram towards the master cylinder side. A check valve (plastic bit at the end of the hose) will trap vacuum inside the booster to give you one or two assisted brake presses when the engine is off or when vacuum is near non-existant (e.g., at WOT).

If you want to tackle this yourself, here are the instructions: viewtopic.php?f=28&t=3413

 

[jzfish]

This is great! Thank you for taking the time to post all of this info for me. If I can get the part in time I will be fixing this over the weekend. I'll let you know how I make out.
John

 

[dlindsay001]

I have a 2005 escape xls 4wd that is having this same hissing problem. Can anyone give me the steps to replace the power brake booster in a 2005?

 

[chriswalker80]

I have the same problem with my brake booster and after reading the step by step instructions I'm going to give it a try myself but, I'm just looking a buying a brake booster from the states so can anyone tell me if there is a difference from removing one from a Left Hand Drive and putting it on a Right Hand Drive vehicle? I'm guessing there might be but, just thought i'd ask. thanks.

oh BTW i live in OZ thats why i'm asking?