Air in brakes, brakes failing and ABS?

[Krystal18]

Thanks @toc

I appreciate your thorough reply and advice Thank you.

I talked to my dad and my brother about your suggestion today (my husband works away from home and is, well, not as good with cars as my dad and brother ).

My dad got the brakes to fail and it seems that disengaging the ABS didn't stop the fault. My dad now doesn't think it's the ABS module but he's going to have a thorough look over the weekend.

My dad has swapped cars with me until we get the brakes sorted once and for all. My dad has the same car as me (only a few months younger) and hasn't had any issues like this.

I'll keep you posted

Thank you again!

[toc]

Thanks Krystal for that test.

I did hope the fuse would show an open solenoid in the ABS module bypassing brake fluid and had hoped removing power would result in a fix, but it is possible that the path is still open with the ABS module off..
As before, my suspicion is entirely on the basis that brake fluid has an easy path back from the caliper, and that's why the pedal goes to the floor.

That leads me to think of another idea to help prove or disprove the ABS module, which is of course to remove it from the brake lines, I haven't fully thought of how that would happen however as once you remove the ABS module, you'll likely be bleeding the system again (to remove air in the new tubing needed to bypass it..) - and we can see that bleeding it - fixes it. So the circumstances to reproduce the problem would have to be nailed down! - How do you reproduce it?? By hard braking which would force ABS on (to prevent skids)?

I'm curious because the ABS module is a concern, when you read how many members have had failed modules and no one seems to identify the actual root cause of the failure.

Hopefully your dad's input can reveal what it isn't, if not also what it is

Thanks again for the feedback to us.

[Krystal18]

Thanks @toc

I also ran your previous suggestion of putting the car up on a hoist and checking if the wheels still spin. My dad has a pit but no hoist so he can't try that. I'll definitely send him your most recent suggestions too and see what he finds

The Mitsubishi dealer and my dad both reproduced the brake fault by running the car stationary and pressing the brakes until it faulted. I think in both instances it took some time. I only drive about 80km a week and the brakes seem to fail every 2-3 months. It's happening in both winter and summer. There's nothing I can pinpoint I'm doing at the time that is consistent (like driving up a hill, or driving for hours, or braking suddenly).

I now recall an issue with my brakes when the car was less than 18 months old. I was driving on the highway (110km/hr) and gently braked for the upcoming 80km/hr zone like I did every day in that part of the road. The brakes didn't work and I pushed them harder which suddenly engaged the ABS (I think) because the car vibrated like never before. I lost control and ended up in the bushes on the side of the road. No idea if it's related to this current issue but it was scary!

I agree: I've heard from the Mitsubishi people about lots of customers with faulty ABS modules but presenting in ways different to my issue. Considering the ABS is such a major part of the car (cost wise and safety wise), they should've done a recall, but I guess they're thinking of $$$$ Replacing a $3,000 part in thousands of cars would be very pricey (lol, but it probably only costs them $100 to make!)

Dora_anne pointed out that there was a recall on the brake booster in some 2008 model Lancers too, but mine (nor my dad's 2008 Lancer) is eligible. Again, anything to do with brakes should be a recall. It's not like it's the volume control on the radio!

I'll keep you posted.

Again, I really appreciate your input and advice!

Have. A wonderful and safe Easter long weekend

[toc]

I now recall an issue with my brakes when the car was less than 18 months old. I was driving on the highway (110km/hr) and gently braked for the upcoming 80km/hr zone like I did every day in that part of the road. The brakes didnt work and I pushed them harder which suddenly engaged the ABS (I think) because the car vibrated like never before. I lost control and ended up in the bushes on the side of the road.

That's interesting, that vibration is indeed the abs working - it basically applies brakes and releases them real quick, and that's what the solenoids are for inside the module.

Now, the master cylinder and brake booster sit behind the brake fluid container, if you push REALLY hard on the brake pedal there's a part inside the master cylinder that can actually get damaged.
See http://forum.miata.net/vb/archive/index ... 96237.html.

The same can happen with abs engaging and a faulty solenoid in the abs module (because brake fluid has an easy path as if the bleeder was open).

If you had scored the seal in the master cylinder, this would have been found and resolved though ... here.. (from your original post)
'Again, even after the master cylinder was replaced, the brakes have failed again. '

Given the fault condition (pedal to the floor!) - I suspect you can also have the master cylinder fault occur, as I can imagine panicked braking (foot to the floor!)..

Has anyone tried to engage ABS when the fault is present? I suppose it's hard to lock the brakes up when you need to go to the floor to get 'standard braking effort' - but that'd be interesting.

[Krystal18]

Thanks @toc. I read the link you sent - thanks!

These events happened 5+ years apart, so they may not be related. But I just thought I'd mention it.

Yes, the master cylinder was replaced (brand new, genuine Mitsubishi, $800 ) I had no idea I could ask for my old parts back because I'm now sure the master cylinder they took out was probably totally fine! Oh well

This is all rather ironic because I bought the Lancer over other cars for its excellent safety. Never thought I'd have ongoing brake problems in a 7.5 year old car!

Thanks again for your input

[toc]

Hi Krystal,

Just curious how this ended up (or if it's still an issue)?

[Krystal18]

Hello toc,

Thanks for checking up on the issue. Nothing new at the moment

My dad has the car sitting in his garage and he's still trying to figure out what's going on. The problem only happens every 2-3 months but my dad can make the problem happen when stationary. He doesn't think it's the ABS but we're still deciding what to do because it's a lot of money for an experiment.

I'll keep everyone updated.

[Krystal18]

Hello toc,

Thanks for checking up on the issue. Nothing new at the moment

My dad has the car sitting in his garage and he's still trying to figure out what's going on. The problem only happens every 2-3 months but my dad can make the problem happen when stationary. He doesn't think it's the ABS but we're still deciding what to do because it's a lot of money for an experiment.

I'll keep everyone updated.

[yatza]

been following this for a bit. i recently had a truck at my work doing a similar thing (pedal would go straight to the floor, next to no brakes). had a new master cylinder, had the brakes bled multiple times, took it to mitsubishi (they bled the brakes again), swapped the abs unit with another working 2nd hand unit. nothing worked.

i got the shits with it and stripped all the wheels off and pulled the calipers. each rear caliper (two on each wheel) had a seized slide giving too much piston travel which is what was making the pedal go to the floor.

have they all been pulled off and inspected for wear and or proper lubrication? the fact it will do it when not even moving tells me that it isnt likely to be an ABS fault.

[Krystal18]

Thanks for your post Yatza

That must've been an expensive fix! The master cylinder and the ABS and it still didn't fix the issue Was the braking problem on your truck constant or intermittent?

If it's the callipers, is it likely that the problem would occur every 2-3 months or would it always be there?

It's a good point you make about the ABS and the brake problem occurring when stationary. Another indicator it's possibly not the ABS.

I'm going to call the mechanic tomorrow and see if he checked the callipers and if not, I'll check if Mitsubishi checked them too.

Thanks!

[yatza]

vehicle was already sold so we had to do it anyway to get a roadworthy.
it was an always there problem. but your problem may be something where with the right conditions it will happen. get jammed or whatever. its the last thing it could be other than a fault with the vacuum pump.

brakes are a closed system, so there is nowhere else for the fluid to go once it its pushed into the lines via the brake master. (no over pressure or return lines) it has to be in the master or a fault with the calipers.