The Falling Brake Pedal Mystery

OK, so this post has nothing to do with MY 4Runner, but this is a 4Runner Family so everyone in my family has one or they get tied to the rack and flogged for eight days…just kidding…maybe.  My wife also owns a 4Runner.  She has a ’99 Limited Gold Edition (Still trying to figure out the difference between the Silver and Gold Editions)

A few weeks ago she noticed that her brake pedal was squishy and dropping to the floor after she came to a stop and then the truck would start to roll again.  I went online to all the sources about this issue and played the “information dance”.  Again, it is this reason I have this blog so you can find the info without 10,000 different opinions on the topic.  Some said it was the master cylinder going south, others argued it was the brake booster.  All of these were valid points, but I wanted to run a series of tests and make my own determination since the online sources were not fixing the issue.

A few months back I had changed out the rear brakes on her 4Runner.  While I was back there, I noticed that one of her wheel cylinders had blown on the driver rear.  I promptly replaced it and attempted to bleed the system with my 74 year old neighbor.  Upon hearing that she was having this issue I thought maybe my friend didn’t understand the procedure for bleeding the brake line as I thought I had explained it rather explicitly.  So the first test we did was to re-bleed the rear driver side brake cylinder with my wife at the helm.  I saw no air or any irregularity in the fluid coming from the line after about 5 times.

Not it.  Moving on.

we next checked for air leaks in hoses with the car on and off.  Nothing.  I checked all of the tubing and hoses for cracks, leaks and so on, nothing.  Back tracking for just a moment, on my old ’99 that I flipped, I had recently replaced the brake booster on mine and had also purchased a replacement check valve.  Well the new unit came with a check valve so I had an extra one lying around.

I went ahead and changed out her old one for the new one I had and we tested the system and that seems to have been the problem.  Now in Texas we dont’ get snow or ice, or if we do it lasts about an hour and its back to summer again, but this truck is approaching 18 years old and we have no maintenance records on it either.  Chances are good it had never been replaced and therefore went bad.  I was right.  A simple $6.00 part from Autozone repaired the issue.  I took it for a test drive and tried to cause teh brakes to fail or repeat the issue and then I had my wife do the same.  We both came to the conclusion that the issue had been resolved.

No moral to the story except to say before you think the worst and buy a $350 part (in this case a brake booster) or $85 on a master cylinder, check the little stuff and see if it works.  I will have her test out the repair throughout the week and see if it comes back, if not, then I just saved a bunch of money by not listening to everyone on the internet!