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

Brake issues can be frustrating to troubleshoot in some cases. One way to narrow it down to the master cylinder, if you press the pedal fully with the truck off, and it bleeds off pressure, then the boot is likely torn and pressure is bleeding past. I've also seen those little tiny holes get clogged, even had a brand new one from a manufacturer I will refrain from naming, with a tiny broken off drill bit in it. Also bench bleeding the assembly is mandatory but I'm sure they covered that, although the loose lug nuts is.....troubling.

Good luck!

 

Brake master replaced, bled system multiple times.. sounds like an internal leak at the ABS/VSC modulator

 

Next time you take it to the dealer, drive one of the brand new trucks and yours back to back and see if they're different. If they are, have them keep it until they're identical.

 

Yeah I actually did that already after the abs actuator was replaced. Completely different. Other truck was super solid and responsive, mine was mushy and limp... Dropping off again this evening, will try to drive another again if time allows.

 

Thanks for that, have read that can cause the same symptoms as well. Will keep in mind and mention to the dealer this time around.
Appreciate all the replies and ideas from everyone

 

Happy to see someone holding on there. Sub'd for outcome. would like to know if there are issues in the future with my Sport.

FYI, I have 78k miles on mine and I had my front pads replaced at 75k miles.

No other brake changes. Planning to do the rears at 100k most likely at the end of the year.

I went with the sport vs the OR because the brake system was simple old school vs the ORs complicated system.

 

Had the exact same happen on a previous vehicle. Could not figure why I couldn't get them bled. Gave up and started shotgunning new parts at it. Finally got them bled and I ended up blaming seals on calipers after looking at them when I replaced them.

OP, good luck. I have experienced vehicles with spongier brakes (probably contributed to me running dot 5), but I would never drive or fly one (except to limp home) where the pedal continued to leak down while standing on it.

BTW, does anybody else think the hydraulic brakes on the pro/or feel more position controlled than force controlled. It's a weird feeling for me...

 

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.

 

this and also try the OR model for acomparison

 

the OR 4x4 and Pro have a completely different brake system.

 

I don't know why this happens but ive been thru with 2 Toyotas 2004 TRD Vacuum assist,and 2014 SR models vacuum assist, youll only be able to get them so good, the brake will always sink low to the floor at a stop but the truck will stop on a dime go figure. eventually youll/dealer will run out of ideas and what to replace but the issue will always exist. I too wasn't satisfied with the softness of the pedal and double pumping the brakes, but I got it as good as it will ever be with a power bleed and rear brake adjustment to where I can live with it.

 

really?

 

I believe you, so not arguing - but why then was it perfect for the first 35k miles and suddenly went soft and wouldn't engage at all until 1/2 way through the pedal travel? Now after all the replacement parts it engages where it should, but the pedal is mush. I'm truly stumped, other than perhaps the caliper seals, rear drums still not adjusted, modulator, or maybe a vacuum leak somewhere.
I think that toyota should be able to get it back to how it came from the factory and was for 2 years before the trouble started. And I can't think of any way the suspension would have affected the brake system (no leaks, overextended lines, new kinks, banged hard lines, etc. etc.)

 

Yes. for the Crawl Control they have a different brake system.

 

IF the rear drums are gummed up with brake dust, dirt, salt, road crap, etc. and haven't been cleaned properly would that potentially cause the pedal/pressure issue? If the pistons/shoes/springs are somehow stuck?
I'm thinking of anything here guys...

 

whatever one has a mechanical assist

 

Sounds Plausabe... opening up the drums doesn't take long with the right tools. 35k miles might give you a good amount of brake dust and mud.

 

if you go search and research this phenomenon in the 2nd gen forum, search >>Soft brakes or spongey brakes you can read a million threads on this exact problem you have sometimes it gets ironed out sometimes not, after all the replacement parts you have on your truck there is almost nothing left to replace except new calipers, cleaning and adjusting the rear brakes does help with the feel a lot and will raise the pedal up.

 

I dont think so. My 1980 mini has rear drums and my old '68 mini had drums all around. never caused that issue.

 

i don't have a 3rd gen but my 2nd gen had long pedal travel due to a bad drum adjuster. The rear drums need periodic adjustment. You should be sure to use the e brake regularly to keep them working correctly.