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While I understand that your problem is likely fixed or the car may have been shuffled out of your inventory, I am curious if you noticed peculiar sights/sounds while idling the engine with the hood open, such as clicks, hisses, or whirring.
I have a sneaking suspicion (or wild guess) that the regular RPM drops were intelligently controlled and may have been related to the A/C pump clutch engaging (additional load), an error occurring, and it disengaging (return to normal).
A quick look at the OEM pad kit doesn’t indicate what they are made of.
I only replaced the driver’s side caliper because it had a stuck piston and the bleeder valve snapped off. The passenger side caliper was serviceable and the bleeder valve was functional, so I didn’t replace it. For what it’s worth, I used Eric’s “push the pistons in with the bleeder valve open” technique and also performed a bleeding procedure on both at the time of service since I had had the bleeder open on one and replaced the other and I wanted to push fresh fluid into them anyway. The service manual for this car instructs to just remove the lid on the reservoir and force the pistons in to accommodate new pads.
I’m not familiar with the different types of pads in use today. I recall back in the day that shops would offer “organic based, economy” pads or “higher performance, semi-metalic” pads at additional cost. The pads I put on, I scuffed with a couple passes of coarse sandpaper before installing and they seemed like they were made of quite soft material. They seem as if they polish the rotor like they were made of soft pencil lead or something. In this regard, they don’t seem similar to the ones that were on the car when I bought it. The high pedal travel was there when I bought the car though, and has steadily gotten worse. Could this really be caused by my gentle-braking habits, or could there be a slow-onset failure happening?
What was the manner in how it was last shut down? Did you turn it off as normal or did it quit on you?
I’ve had a problem like that and it was caused by the negative battery terminal being loose and corroded. It had enough of a connection to power the accessories, but when I turned the key to “start” all I got was dead battery symptoms.
Speaking of which, is your battery fully charged?
Thank you for your input. I suspect that the front/rear imbalance may self-correct as my new brakes wear in and I get some car wash wax and rainy day grime on the rotors. I am also looking into the “brakes have air in them” possible situation.
I just bought a “backup car” today for $500. This should be full of fun maintenance and repairs to practice on. Anyway, searching for an online owner’s manual for it helped me find a few service manuals for my Pathfinder (the subject of this thread) that were previously beyond my search engine skills. Most notably, I found a manual for the braking system.
The brake bleeding procedure is “…front left, rear left, front right bleed valve, in that order.” It doesn’t mention the rear right, but I suspect that to be a typo and that it should follow the front right.
Also found was a diagram of the brake system piping. It shows both lines from the master cylinder going to “actuator” and from that, all 4 lines to the wheels come out. The two rear lines go into one “connector” and both come out of it and proceed to the rear brakes.
Now, also in that manual are instructions for “burnishing” the brakes. This is a similar procedure to the video for slamming on brakes to restore a soft pedal, but the instructions given are to stop from about 30MPH in 3-5 seconds, drive for 1 minute at 30MPH to cool brakes and repeat, performing the sequence 10 times. The instructions for when to do this are described as “…after refinishing or replacing rotors, after replacing pads, or if a soft pedal occurs at very low mileage.”
Now 3-5 seconds from 30-0MPH doesn’t seem all that forceful, and I probably do that now and then anyway. So I’m back to possible air in the lines (if the system corrects for and keeps the brakes balanced so that it’s not as obvious as it was when I failed to bleed my brakes on an ’81 Citation), or perhaps some sort of failure in another component.
There were instructions on testing the brake booster, which I’ll perform as soon as I can. Can a vacuum leak or other problems with the brake booster cause long brake pedal travel? If it helps, I’ve found that pumping the brakes with the engine off gets the pedal to harden up, whereas that is not the case with the engine running. In comparison, the brakes in the 2001 Sunfire I just bought today are forceful and immediately felt with very little brake pedal travel. I estimate at least 10 but probably 20 or more times more travel is required to slow the Pathfinder the same amount. This is going by feel and not measurement, but the Sunfire feels like braking is controlled by force against the pedal while the Pathfinder seems to brake by pedal distance moved. In an incident involving a deer last year, the desired “panic stop” was not achieved, even though I can activate the ABS if I put my mind to it and push the pedal to the floor. Fortunately, I was able to dodge the deer enough that it ran into my front wheel, caused no damage, and walked away. So, come to think of it, the soft pedal is a serious problem, and I’ve succumbed to the “frog in heating water” effect.