Brake Pressure Loss, Many Parts Replaced, No FIX...

Well that was my next thought... unless something is way out of adjustment with the push rod or in the rears. They claimed to have machine-bled the system many times now, certainly after replacement of each part so I don't know how air could possibly be in the system anywhere at this point.

 

They're using Techstream to bleed the actuator?

 

Good question - they didn't mention it. I will ask next time I talk to them. Thanks

 

ask them if they used the BG bleeding machine its the best one, if they did use it , it should be listed on the invoice as brakes bled using BG machine, not all dealers have this machine, but it pressurizes the Master cylinder and sucks the fluid out of the bleeder screws leaving no air in the system

 

I would hope they are able to bleed the brakes and abs module correctly, that would absolutely amaze/dumbfound me if that was the problem. It is not rocket science by any means.

 

I emailed and asked the question. Hopefully the service manager calls me back tomorrow as promised.

Agreed... they are a reputable dealer, and I've not had bad experiences with their work, etc. yet. (It's Koons Tysons in northern VA by the way, in case anyone's local to the DC area.)

 

You would think...
Not rocket science, but...

 

Some vehicles with front disc and rear drum systems have a porportioning valve design to deliver the correct pressure to all wheels equally. I remember reading somewhere that it can become off center from improper bleeding. Disclaimer: I read it on the Internet, so I'm not responsible in any way.

 

there's

 

Another update - service manager called last night and said he and the master tech think it’s fixed and the pedal now has normal pressure. They replaced both front rotors and pads to see if that would help. He told me that the tech inspected the pads and found them to be worn (not to the point of needing replacement) and to have built up some rotor material causing brake fade. That’s all well and good, but partially worn pads don’t cause a loss of pressure in the pedal... so perhaps the last time it was bled (using a bg machine) did the trick along with all the other new components they replaced?
FYI they replaced the rotors under warranty exactly a year ago because they were warped (found to be defective) with only 19k miles or so. Now I’m at 35,700.
He requested I pick it up Monday when he is there again so he can personally drive it with me to make sure. I respect that. We’ll see what happens Monday.

 

Good luck, half worn pads do not sound like they are the solution to the problem

 

sounds good just do a good road test to make sure alls good

 

Oh, I will for sure. Thanks for the advice and all so far everyone. Kind of a crap issue for a 2-year old "new" truck. 95% of it has been wonderful for me, and our pup loves it.

 

most Toyota trucks I have owned(even new ones) had little issues that once ironed out the truck is the best most reliable on the road,

 

Got my truck back yesterday... Situation is the brakes now engage consistently where they should, BUT the pedal is still super spongy and can be pressed to the floor slowly with consistent pressure. This should not happen.

Short version of everything that's been done in the past 3 weeks:
abs actuator replaced
brake master cylinder replaced
brake booster replaced
front rotors and pads replaced (their idea, shouldn't have made any diffference)
system was machine bled before any parts were replaced, and after each part was replaced.

Decided to drive it for a day to see what my own thoughts were beyond a fairly short test drive (I did drive local roads and highway in the road test with the service manager). It is loads better, and I don't feel unsafe. But the spongy brake feel is not normal, and I believe should still be fixed.
Lastly, I checked a few things last night on my own. Found that they over filled the brake fluid, and that 2 of my lug nuts weren't tight (I always check them to be sure). They adjusted the e-brake as well, and I feel that it's now too tight...

I'm at a loss. Next I guess would be have them pull apart the rears? check for air in the rear pistons?

 

the soft spongey brake pedal IS normal in the 2nd gen,3rd gen trucks equipped with the vacuum assist system, the OFFROAD TRD models have an mechanical assist system where the soft brake doesn't exist. all you can do is get the brakes to function and feel adequate on the trucks with vacuum assist they will never be rock hard pedals. you have to get used to it or get an OR model, the dealer has done more than he can do for it.

 

True. I've seen pad rivets gouge into rotors before that never had a brake fade problem.

The fade to floor sounds like a problem.

 

When I have had issues similar I pay very close attention to the fluid coming out when bleeding. It needs to be determined IF air is coming out. IF there consistently is air coming out AFTER a successful bleed previously then you know there is an issue with air entering the system. IF there is no air coming out in the fluid your problem is elsewhere.

The reason for determining if air is the issue is you can have bad seals at the callipers (or anywhere else but usually callipers) they may not leak fluid BUT they will suck air back past the seals on retraction. It is an odd situation but I had one situation where I bled the brakes for 2 hours straight with no success. Left them overnight to allow the air to collect into larger bubbles and tried again. Still no luck. Put new seals in the callipers and they bled up in 30 seconds.

At this point they are either missing something in the diagnosis or are going by the remove and replace method of troubleshooting.

 

I have heard that, but I had never experienced it in my TRD Sport since purchasing new 2 years ago. I've had 35,000 miles of solid brake feel and pressure, until suddenly this issue occured. Strange...

 

My old 2000 and 2008 Off Road Tacoma's had traditional style Brakes with a Vacuum Booster and the brake pedals were always rock solid. If your pedal is still fading to the floor then there is a problem, sure sounds like an internal leak in the master cylinder.