Hey all,

So I'm trying to correct a bad flush of my brake fluid. In short, the master cylinder was run dry. We've been bleeding the brakes (3 times now) to try and fix it. THey feel much better, but I do have a few questions:

1. Is it normal for the brake fluid level is the reservoir to RISE after driving? First thing in the morning it was at MAX, after driving for a while in the heat, it's about 3/4" above max.

2. At a stop sign or a light, I can depress the pedal pretty damn far. I cannot recall if I could do this before all this trouble. Does that sound normal? It seems that I have good stopping power.

3. How will we actually know if we get all the air out of the lines? Do I need to take it to Mitsubishi to do a pressure bleed? I have read that air can get trapped in areas that a regular bleed can't get out.

A mechanic up here says even if the master cylinder ran dry (it was gravity bled when it went dry - no pedal pressing), that just doing regular bleeds will be fine. ANy thoughts on this?

Sorry for all the questions lately, I basically didn't listen to the advice to DIY and now might be paying for it.

THanks,
Dave

 

1. I don't think it's normal for the fluid level to rise. You mentioned previously that after the pads were changed and the brakes bled shortly after, that the wheels got very hot -- as if the pads were constantly rubbing the rotors. Are they still hot after these most recent bleeds? If they are, the calipers are probably getting very got, and so is the fluid inside them, and the thermal expansion of the fluid within the caliper may be the cause of the rise in the master cylinder level.

2. The brake pedal going down "pretty damn far" is not normal. If someone you know has an Outlander, or there is a Mit dealer near by, hop in a different Outlander and depress the pedal to compare its operation to that of yours. If they're the same, good. If they're not, bad.

3. I, too, understand that after a brake system gets infiltrated with air that sometimes a pressure bleed is the one and only solution. Are you doing the two-person method of bleeding now, or are you still doing the just-let-it-drip routine. If the latter has not made things right, do the two-person method as a last-ditch. The two-person method is actually a type of DIY pressure bleed. Tell the person operating the pedal to first "pump it up" and then "now push down really hard and hold", as you open each bleed valve and the pedal plummets to the floor. If you hear air bubbles coming out with the fluid, you'll know what you're doing is effective. Bleed each wheel until you hear absolutely no air bubbles coming out. Even go around the circuit twice and make sure that you follow the sequence described in the Mit service manual. You'll know if the job has been done adequately when the pedal operates the brakes like that other vehicle you've compared yours to. If the two-person method does not work, just find the least expensive, but competent, place to do a pressure bleed ............and keep your fingers crossed that the pressure bleed brings pedal/brake operation back to normal. If it does not, it's time to go to the stealership. (Don't forget the lubricant.)

Good luck.

 

You never bled the system properly.

Gravity bleed the system again, this time close off the nipples starting from the furthest from the master cylinder to the closest. Then take the car for a drive, and STOMP on the brakes. Lock them up or engage the ABS at slow speeds. This should produce a good firm pedal.

If that fails, do a force bleed. Go to autozone and get some tubing that will fit over your bleed nipple. Get about 8 feet so that you can reach from the caliper to the engine. Now remove a vacuum line, attach the other end of the bleed hose, and start the engine. Watch for bubbles, keep the master cylinder full, and start with the furthest from the master cylinder.

If your pedal is still weak, then I'd say your master cylinder either needs to be rebuilt or replaced.

It is normal to rise after driving. Thermal expansion makes that happen.

 

Trust me, I already bought the lube after my experience I had - no need to buy more for the dealership . Actually, they only quoted me .5h labor for a bleed, so I might just get them to do a pressure bleed.

So I got one vote for normal and one vote for not normal for the fluid rising in the reservoir. I just never paid attention to it before so I really have no idea. I would expect it to expand a bit though.

I know there was air in the system at one point since the brake fluid level went down about an inch overnight 2 nights in a row. It has stopped going down so I am pretty sure it isn't a leak.

as for the brake pedal depressing far, the nearest dealership is an hour and a bit away, so I can't test one from there easily.

After the bleeds (it was a 2 person bleed but not in that special order..just started at FR and FL and then RL and RR)), the rears are still pretty damn hot (moreso the passenger rear). The rears are hotter than before we did any work on the car. Now, when we did the pad replacement, is there any adjustment you can make for the pad clearance to the rotors? He just pushed the pistons back in (he didn't need a special tool for the rears - they slid in just like the fronts did with the C clamp), put the new pads in and that was it out the sliders back in and that was it. Did he miss something?


Does bleeding in a certain order actually make a difference? Can you explain why? I'm just curious. Yeah, if that is the case, it was done wrong. So can a pressure bleed remove trapped air from a master cylinder?

At this point, I am willing to just pay the dealership an hours labor to do this to correct this mess

Thanks for your patience with all this.

 

The bleeding order does influence it a lot, as any mechanic will tell you. Mostly it's a pedal pressure/feel difference. I'm not quite sure why that is the case, but in my experience I've found it to be true.

You should also make sure you haven't mixed different kinds of brake fluid. You should not use a mineral type with a synthetic. You should bleed the lines enough to get all the old fluid out.

Personally, I haven't seen a master cylinder retain air bubbles before. If there's air, most of the time it'll just sink to the floor even with one tiny bubble. The issue is the fact that brake fluid is hygroscopic, meaning it pulls moisture. That's what causes the spongy pedal, because water does actually compress slightly, more so than hydraulic fluid.

 

It was new synthetic DOT 4 replacing stock DOT 3. But like I said, he let the MC run dry on the front gravity bleed, then did the two person bleed on all lines after refilling it, so I am thinking it is all new fluid now. Plus we did it three extra times. As for the air in the MC, people actually freak out if they let that thing go dry as they say it is BRUTAL to get all the air out of it and will have to remove it and bench bleed it. Again, I have no experience with this, but since he said he let it run dry, that may be what's happening. So I doubt a pressure bleed would remove that air in the MC or everyone would do that rather than remove the thing.

I went out and engaged the ABS a bit...not a lot but a bit. The pedal feels pretty good when actually stopping...My concern is when I am stopped at a light or just in the driveway not moving..I can depress it pretty far. Mayybe next time you get in your car, just turn it on and see if it feels like you can depress the pedal farther than you think so should.

I am not sure why the rear brakes are heating up as much as they are. My knowledge is the front ones do most of the stopping, hence they should be hotter right? But my passenger rear is definitely hotter than the others. I flicked a very tiny amount of water (a few drops) on each rotor after a 15 minute drive or so with normal braking..only the passenger rear rotor sizzled. It isn't at the point where I will get a burn touching the alloy rim, but it is hotter. Is thre anything special about the rear caliper piston I need to know? Just push it in and done right?

 

Was the Mit procedure followed (all the pieces removed, cleaned and re-lubricated) when the pads were changed? If not, remove the new pads and pieces from the hottest wheel, make sure that caliper's piston is fully pressed in, re-install the pads and pieces and lubricate those parts recommended in the procedure and see if that wheel still remains the hottest under operation.

 

Hmm, the wagner pads already had shims on them. According to the instructions with the pads, it said to put some grease on the back and install, so that's what was done. It sounded like it wanted the gear on the back of the shim, which he thought was weird. He did say the caliper was fully retracted and I watched this and it was. The sliders were cleaned andlubricated..I am assuming he knew what to lube them with. They were put back in the right spots and tightened back up.

Could the gear on the back of the inner pad cause this? That is the only thing that was a it odd according to him

 

Sorry..grease, not gear

 

slider pins get lubed with caliper grease. The grease on the back of the pads is supposed to help with vibrations that we hear as squealing.

I've never had much luck with 2-man bleeding. Vacuum is stupid easy and a 1man job.

Sebba, interesting idea with the vacuum line idea. you could effectively get by with just the canister setup of a hand pump setup, but using the engine's vacuum source. You'd need some long lines for the rears...but doable.