2003 4runner v8 brakes/MC issue

[saint123]

Ah damn, I missed that! Good catch, I was thinking he was talking about a twisted up o-ring not a contamination issue; but now it makes sense with his other issues.

[MENTION=98163]saint123[/MENTION] Well now you have a big problem on your hands. You need to replace all the calipers and rubber lines (You should be okay with the MC since you just replaced it) and you need to flush de-natured alcohol through all the lines after you put new calipers and hoses on (I would just get a gallon from the hardware store and run it all through.) Afterwards you'll need to flush it with brake fluid and have it bled properly with a scantool.

Excuse my naivety but is that a must? How about flushing with 3 bottles of brake fluid?
Also I did not notice any noticeable dilation in the caliper rubber orings - if that has any significance at all...

 

[BlackWorksInc]

Excuse my naivety but is that a must? How about flushing with 3 bottles of brake fluid?
Also I did not notice any noticeable dilation in the caliper rubber orings - if that has any significance at all...

The problem is that there's contaminant in the system, now theoretically if you flush a ton of brake fluid through the system it should be okay. But, we don't know what was put into the system and if it combines or repels brake fluid; which means there could be nasty gunk still in the system.

The correct procedure is to replace anything that has rubber in the system with new components and then flush it with denatured alcohol to clean the metal lines. We've had to do this a couple of times on vehicles because customers put something other than brake fluid in the vehicle, it could be why your old master cylinder failed.

Though since you already built the front calipers (and hopefully the rears are okay, though it sounds like one is leaking for a different reason) you may want to just run denatured alcohol through it and then bleed it with fresh brake fluid. Worst case is that you'll have to replace the rear calipers and the rubber lines anyways.

~

Is there any chance you may have used the wrong fluid at some point? When was the last time the vehicle had the brake fluid changed prior to this? Can you post a picture of the old master cylinder and the seals?

 

[nevada]

Ah damn, I missed that! Good catch, I was thinking he was talking about a twisted up o-ring not a contamination issue; but now it makes sense with his other issues.

[MENTION=98163]saint123[/MENTION] Well now you have a big problem on your hands. You need to replace all the calipers and rubber lines (You should be okay with the MC since you just replaced it) and you need to flush de-natured alcohol through all the lines after you put new calipers and hoses on (I would just get a gallon from the hardware store and run it all through.) Afterwards you'll need to flush it with brake fluid and have it bled properly with a scantool.

thanks.
we see that happen a LOT here at the shop. many people confuse power steering fluid/ATF compatibility with brake fluid/PSF, and end up topping their system off with steering fluid. oops.

The problem is that there's contaminant in the system, now theoretically if you flush a ton of brake fluid through the system it should be okay. But, we don't know what was put into the system and if it combines or repels brake fluid; which means there could be nasty gunk still in the system.

The correct procedure is to replace anything that has rubber in the system with new components and then flush it with denatured alcohol to clean the metal lines. We've had to do this a couple of times on vehicles because customers put something other than brake fluid in the vehicle, it could be why your old master cylinder failed.

Though since you already built the front calipers (and hopefully the rears are okay, though it sounds like one is leaking for a different reason) you may want to just run denatured alcohol through it and then bleed it with fresh brake fluid. Worst case is that you'll have to replace the rear calipers and the rubber lines anyways.

~

Is there any chance you may have used the wrong fluid at some point? When was the last time the vehicle had the brake fluid changed prior to this? Can you post a picture of the old master cylinder and the seals?

wouldn't it be a better idea to flush FIRST, then replace the rubber parts? that way the flush doesn't push the oil across the NEW rubber?
or does the alcohol break down the oil well enough that it doesn't matter?

 

[BlackWorksInc]

thanks.
we see that happen a LOT here at the shop. many people confuse power steering fluid/ATF compatibility with brake fluid/PSF, and end up topping their system off with steering fluid. oops.



wouldn't it be a better idea to flush FIRST, then replace the rubber parts? that way the flush doesn't push the oil across the NEW rubber?
or does the alcohol break down the oil well enough that it doesn't matter?

You know... I don't know if its better to flush first or not? I was always told to do it that way; I've only done it a couple times at the shop and that's how we ended up doing it? I would assume the denatured alcohol breaks it down, otherwise we'd just use brake fluid if we're just trying to push the fluid out.

 

[saint123]

Would be interested in the pictures, my old one failed at one of the o-rings in the master cylinder piston.

The TRAC/VSC lamps are one most likely because your ZPC (Zero Point Calibration) is incorrect from installing a completely new Master Cylinder Assembly (Also if the battery goes below about 12v on '03 & '04 models), they could also be on if you turned the vehicle on with it unplugged at any point and/or from trying to bleed the system too many times and pressure not improving (it would set a DTC for pressure loss).

I would try disconnecting the battery for about 10 minutes, relearning the idle (letting it idle for about 5-10 minutes with no loads on) and then performing the ZPC Re-Learn. You'll probably still need to have the system bled via scantool after you repair the leaking fitting as air has most lik ely gotten in due to the repair (the FSM says any time the MC is removed it needs to be bled via scantool driven methods.)

ZPC solved the lights issue. The reservoir pics for reference posted here