BRAKES losing presure! any ideas

[Big Dad]

This is probably going to sound smartassy but it's not intended to be.

Have you ever used your e-brake?

Till you get this anomaly figured out I'd suggest that you actually use the e-brake a few times, you know, in case you ever really need to you'll know how it reacts.

A lot of people just take the e-brake for granted and never use it or never really know how to use it when the immediate need arises.

[sbsisco]

no offense at all...actually with my trip planned to colorado next month and a known break issue I can't figure out ..has got me motivated to experiment with that very thing - just incase. I'm pretty shure it would be a really low chance I'd completely loose front and rear parts of my master cyl in the same trip but it could happen. I'm taking it in to another dealer in the morning and hopefully with the explanations its going to the san juans they'll look a little closer than the others have...at the very least I'll keep my reciept to prove i tried to get it fixed incase those brakes force me to take the fast way down black bear pass..seriously, with it in 4 wheel low and the fact the pedal has yet to go all the way to the floor (ebrake as back up plan)...I'm pretty certain I can keep it on the trail but I'd feel a lot better if I can get that MS changed out. At least it won't take me by suprise, its been doing it long enough im getting used to it.

[Big Dad]

I hope you don't take this $hit the wrong way...I'd hate to hear that someone crashed while using the ebrake....

You do know that while you're driving it's best to pull the brake release handle/ lever (depending on the application) while you apply foot pressure to the ebrake, that way if you start to lock up the brakes you can ease up on the ebrake and it'll retract to it's normal position instead of locking up the brakes.

Again, sorry to imply the obvious but a lot of people don't know how to really brake using the ebrake.

As far as the problem goes, I haven't noticed anything like it with my 3. I have about 22k on it at this point. I'm sure you'll figure it out though.

[timgco]

Document every time it has failed. Since this a safety issue, and you local dealer cannot duplicate it, this is one of those times you may want to get the factory rep involved. I cannot tell from the avatar, but it looks like you might be lifted????? IF that's the case, check your added breaklines. I had a similar experience with a lifted truck last year. It turned out to be on the fitting was bad AND that same line had swelling also. It was ready to go but not obvious at first glance. ...just a thought.

[evldave]

This is exactly what happened to me at about 15-20k. It ended up being air in the brake lines - the dealer had to bleed them 3 times before they were fine. I'm still hyper-aware of the issue, and sometimes it feels like they are getting squishy. Most dealers have a fancy machine - it takes them all of 15 minutes! I'm taking mine in for some other warrantee work later this week and will ask they rebleed them.

Keep pushing your dealer. By the time I was able to get in the dealer (mine started in California and I live in Washington), I was on long grades and almost completely out of brakes...if your problem is the same as mine, it will get worse and you will likely end up out of brakes. Hope this helps

[Ryan Graham]

Brakes can't just all of the sudden "get air" in the lines. Sounds like a bad master cylinder, but older chev trucks had a problem with the abs "dump" valve doing the exact same thing. I'm with you though on not messing with the H3's system. With the traction control and abs and all the other stuff bolted to the master, you may never get it to bleed out properly if you did replace it. If a master cylinder is failing, you can get the pedal to the floor the same way you described and any shop should be able to check the same way you did. Sorry you have such lame mechanics out your way.

[pdsq99f4]

Sounds like your master cylinder. I've replaced a few and it is not fun due to the H3's electronic booster and ebcm being bolted to it. There is an bleed procedure that you need a Tech2 scan tool to perform.