User Tag List

Reply
 
Thread Tools Rate Thread Display Modes
Old 07-24-2023, 03:07 PM #1
TeryT's Avatar
TeryT TeryT is offline
Senior Member
 
Join Date: Feb 2004
Location: Scottsdale AZ
Posts: 1,410
TeryT is on a distinguished road
TeryT TeryT is offline
Senior Member
TeryT's Avatar
 
Join Date: Feb 2004
Location: Scottsdale AZ
Posts: 1,410
TeryT is on a distinguished road
Curious Brake Fluid & Pad Situation

I had to add brake fluid twice in about a month to maybe six weeks time, after some mountain driving. The light would come on; I'd add fluid and drive a couple weeks, then light pops on again. I crawled around underneath, but couldn't see a leak anywhere. I also felt in back of the master, but nothing.

So I took it to the local dealer (the one in Scottsdale is renowned for great, honest service) and they said it was due to the rear pads being so far down, and that the fluid was going into the rear pistons. They said they found no leaks including at the master cylinder. They said the pads were down to needing replacement, so I had them do it and turn down the rear rotors (first time).

So I'm wondering about two things:
1. Why would I have to add fluid twice in about a month? I've certainly experienced where pads wearing causes the pistons to use more fluid, but why would it be down twice in a few weeks, to the point that the light came on both times?

2. I had the rear pads changed at 198k and now have just under 235k, so why would the pads need changing again? I was in the mountains when I had them changed last time (198k) - do you think that mountain shop perhaps used really cheap pads . . . or didn't turn the rotors?

I had always had rears last 2-3 times what the fronts would before needing changed. But the service writer told me the the electronic proportional braking system may actually have the rears engage a couple nano-seconds before the fronts, to keep nose dive at a minimum. And supposedly, because I tow a trailer occasionally, the system might apply more power to the rears. But to have them needing replacement after only 37k doesn't make much sense to me . . .

I'm puzzled!

What do y-all make of this?
__________________
2003 V8 4x4 Sport 4Runner TRUCK OF THE MONTH SEPT. 06 - still tows a 25' ultralite Rockwood 2502 travel trailer all over creation!
MODS: GlowShift tranny temp gauge; Hayden 526 tranny cooler/fan combo; Hopkins Insight brake controller; Bilstein 5100 shocks
Hensley Arrow hitching system - quite simply the best for zero sway towing!
TeryT is offline   Reply With QuoteReply With Quote
Old 07-24-2023, 06:34 PM #2
MikeinNH67's Avatar
MikeinNH67 MikeinNH67 is offline
Senior Member
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 1,186
Real Name: Mike
MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice
MikeinNH67 MikeinNH67 is offline
Senior Member
MikeinNH67's Avatar
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 1,186
Real Name: Mike
MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice
Interesting info. The fluid is entering and leaving the brake cylinders every time you touch the brakes. Having to refill in such a small time frame is odd to me unless there's a leak. If this was a different vehicle I would wonder if the brake booster is leaking fluid into the intake but these are run by motor not vacuum so not that. Cheap brake pads that wear quickly could account for it but they would need to wear extremely fast.

It does seem like these cars use the rear brakes just as much as the fronts which is unlike other cars I have had in the past. When I had a sticking caliper I monitored all of them with a laser thermometer and found the rear brakes seem to run as hot or hotter than the fronts. May be worth monitoring temps for a bit. Sticking (open) front calipers may force more braking to the rear. Sticking (closed) rear calipers may wear out the rears quicker. All things you can figure out by comparing rotor temps after braking or with little to no braking as in roll to a stop.
__________________
Mike

03 4runner Limited
1GR-FE V6 w/199k miles
MikeinNH67 is offline   Reply With QuoteReply With Quote
Old 07-25-2023, 11:52 AM #3
TeryT's Avatar
TeryT TeryT is offline
Senior Member
 
Join Date: Feb 2004
Location: Scottsdale AZ
Posts: 1,410
TeryT is on a distinguished road
TeryT TeryT is offline
Senior Member
TeryT's Avatar
 
Join Date: Feb 2004
Location: Scottsdale AZ
Posts: 1,410
TeryT is on a distinguished road
Quote:
Originally Posted by MikeinNH67 View Post
Interesting info. The fluid is entering and leaving the brake cylinders every time you touch the brakes. Having to refill in such a small time frame is odd to me unless there's a leak. If this was a different vehicle I would wonder if the brake booster is leaking fluid into the intake but these are run by motor not vacuum so not that. Cheap brake pads that wear quickly could account for it but they would need to wear extremely fast.

It does seem like these cars use the rear brakes just as much as the fronts which is unlike other cars I have had in the past. When I had a sticking caliper I monitored all of them with a laser thermometer and found the rear brakes seem to run as hot or hotter than the fronts. May be worth monitoring temps for a bit. Sticking (open) front calipers may force more braking to the rear. Sticking (closed) rear calipers may wear out the rears quicker. All things you can figure out by comparing rotor temps after braking or with little to no braking as in roll to a stop.
Yes, it is interesting and thanks for the info about the vacuum line not being a leak potential!

I just had the 4R back in so they could rework something (not brakes) they hadn't done right, and I had them check for leaks again. They doubled down on the leak, saying there wasn't one. But it is for sure an oddity (and also the pads wearing so quickly in the back). I will definitely be keeping a closer eye on those rear brakes!

BTW - someone else said they wondered why the rear disks weren't as large as the front ones on vehicles now, since they are being utilized more these days. It just occurred to me that even though the rears are being used more than they used to be, the front end gets more weight due to inertia (and also with the extra weight of a V8 on mine). Is that thinking correct?
__________________
2003 V8 4x4 Sport 4Runner TRUCK OF THE MONTH SEPT. 06 - still tows a 25' ultralite Rockwood 2502 travel trailer all over creation!
MODS: GlowShift tranny temp gauge; Hayden 526 tranny cooler/fan combo; Hopkins Insight brake controller; Bilstein 5100 shocks
Hensley Arrow hitching system - quite simply the best for zero sway towing!
TeryT is offline   Reply With QuoteReply With Quote
Old 07-26-2023, 08:46 AM #4
TTucker TTucker is offline
Junior Member
 
Join Date: Jul 2023
Location: Florida
Posts: 23
TTucker is on a distinguished road
TTucker TTucker is offline
Junior Member
 
Join Date: Jul 2023
Location: Florida
Posts: 23
TTucker is on a distinguished road
Very interesting.
TTucker is offline   Reply With QuoteReply With Quote
Old 07-26-2023, 09:49 AM #5
Drcoffee's Avatar
Drcoffee Drcoffee is offline
Senior Member
 
Join Date: Jan 2012
Location: Somewhere, yet nowhere
Posts: 1,739
Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice
Drcoffee Drcoffee is offline
Senior Member
Drcoffee's Avatar
 
Join Date: Jan 2012
Location: Somewhere, yet nowhere
Posts: 1,739
Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice
Quote:
Originally Posted by TeryT View Post
I had to add brake fluid twice in about a month to maybe six weeks time, after some mountain driving. The light would come on; I'd add fluid and drive a couple weeks, then light pops on again. I crawled around underneath, but couldn't see a leak anywhere. I also felt in back of the master, but nothing.

So I took it to the local dealer (the one in Scottsdale is renowned for great, honest service) and they said it was due to the rear pads being so far down, and that the fluid was going into the rear pistons. They said they found no leaks including at the master cylinder. They said the pads were down to needing replacement, so I had them do it and turn down the rear rotors (first time).

So I'm wondering about two things:
1. Why would I have to add fluid twice in about a month? I've certainly experienced where pads wearing causes the pistons to use more fluid, but why would it be down twice in a few weeks, to the point that the light came on both times?

2. I had the rear pads changed at 198k and now have just under 235k, so why would the pads need changing again? I was in the mountains when I had them changed last time (198k) - do you think that mountain shop perhaps used really cheap pads . . . or didn't turn the rotors?

I had always had rears last 2-3 times what the fronts would before needing changed. But the service writer told me the the electronic proportional braking system may actually have the rears engage a couple nano-seconds before the fronts, to keep nose dive at a minimum. And supposedly, because I tow a trailer occasionally, the system might apply more power to the rears. But to have them needing replacement after only 37k doesn't make much sense to me . . .

I'm puzzled!

What do y-all make of this?
The rear pads should last 100k miles. If they arent, most likely your calipers are sticking or corroded and need replacement.

The front brakes still operate on vacuum from the engine. Only the rears are run by a mechanical pump. It could be a leak from the master into the vacuum drum on the firewall. Id start with the rear calipers, check for uneven wear on all 4 pads. If they are original, change the calipers out. If the fluid still seems to vanish, look at the master cyl. That would be a service shop job.
__________________
2007 4Runner Sport 4WD 4.0L 228,000 miles
The real stats on gun murders in America compared to the world (link)
Good riddance to the Clinton Crime Family--> I Voted TRUMP…how’s it going for you now Trump is gone? Be careful what you ask for. You may just get it.
Drcoffee is offline   Reply With QuoteReply With Quote
Old 07-26-2023, 04:09 PM #6
MikeinNH67's Avatar
MikeinNH67 MikeinNH67 is offline
Senior Member
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 1,186
Real Name: Mike
MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice
MikeinNH67 MikeinNH67 is offline
Senior Member
MikeinNH67's Avatar
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 1,186
Real Name: Mike
MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice
Quote:
Originally Posted by Drcoffee View Post
The front brakes still operate on vacuum from the engine. Only the rears are run by a mechanical pump.
Ah, I never realized this.
__________________
Mike

03 4runner Limited
1GR-FE V6 w/199k miles
MikeinNH67 is offline   Reply With QuoteReply With Quote
Old 07-26-2023, 04:41 PM #7
AuSeeker AuSeeker is offline
Senior Member
 
Join Date: Nov 2016
Location: South Carolina
Posts: 4,639
Real Name: Skip
AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future
AuSeeker AuSeeker is offline
Senior Member
 
Join Date: Nov 2016
Location: South Carolina
Posts: 4,639
Real Name: Skip
AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future AuSeeker has a brilliant future
Quote:
Originally Posted by Drcoffee View Post
The rear pads should last 100k miles. If they arent, most likely your calipers are sticking or corroded and need replacement.

The front brakes still operate on vacuum from the engine. Only the rears are run by a mechanical pump. It could be a leak from the master into the vacuum drum on the firewall. Id start with the rear calipers, check for uneven wear on all 4 pads. If they are original, change the calipers out. If the fluid still seems to vanish, look at the master cyl. That would be a service shop job.
I don't believe that is correct, I don't have a "vacuum drum" on my 2004 That I have ever seen, or a vacuum line either, I will look closer when I get the time hopefully tomorrow or the next day.

Also a "vacuum drum" is called a vacuum booster and it also doesn't show up when looking at online dealer parts website in the diagram of the brake system.
__________________
2004 Limited V8
AuSeeker is offline   Reply With QuoteReply With Quote
Old 07-26-2023, 09:53 PM #8
TeryT's Avatar
TeryT TeryT is offline
Senior Member
 
Join Date: Feb 2004
Location: Scottsdale AZ
Posts: 1,410
TeryT is on a distinguished road
TeryT TeryT is offline
Senior Member
TeryT's Avatar
 
Join Date: Feb 2004
Location: Scottsdale AZ
Posts: 1,410
TeryT is on a distinguished road
Quote:
Originally Posted by AuSeeker View Post
I don't believe that is correct, I don't have a "vacuum drum" on my 2004 That I have ever seen, or a vacuum line either, I will look closer when I get the time hopefully tomorrow or the next day.

Also a "vacuum drum" is called a vacuum booster and it also doesn't show up when looking at online dealer parts website in the diagram of the brake system.
Yeah, I don't see any drum either, but maybe they're using vacuum in another way perhaps?
__________________
2003 V8 4x4 Sport 4Runner TRUCK OF THE MONTH SEPT. 06 - still tows a 25' ultralite Rockwood 2502 travel trailer all over creation!
MODS: GlowShift tranny temp gauge; Hayden 526 tranny cooler/fan combo; Hopkins Insight brake controller; Bilstein 5100 shocks
Hensley Arrow hitching system - quite simply the best for zero sway towing!
TeryT is offline   Reply With QuoteReply With Quote
Old 07-27-2023, 12:07 PM #9
MikeinNH67's Avatar
MikeinNH67 MikeinNH67 is offline
Senior Member
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 1,186
Real Name: Mike
MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice
MikeinNH67 MikeinNH67 is offline
Senior Member
MikeinNH67's Avatar
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 1,186
Real Name: Mike
MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice MikeinNH67 is just really nice
Quote:
Originally Posted by AuSeeker View Post
I don't believe that is correct, I don't have a "vacuum drum" on my 2004 That I have ever seen, or a vacuum line either, I will look closer when I get the time hopefully tomorrow or the next day.

Also a "vacuum drum" is called a vacuum booster and it also doesn't show up when looking at online dealer parts website in the diagram of the brake system.
I just looked at my truck and see no vacuum lines going to the brake area and certainly no bulbous booster. I figured I missed something but I guess not this time.
__________________
Mike

03 4runner Limited
1GR-FE V6 w/199k miles
MikeinNH67 is offline   Reply With QuoteReply With Quote
Old 07-27-2023, 08:03 PM #10
Drcoffee's Avatar
Drcoffee Drcoffee is offline
Senior Member
 
Join Date: Jan 2012
Location: Somewhere, yet nowhere
Posts: 1,739
Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice
Drcoffee Drcoffee is offline
Senior Member
Drcoffee's Avatar
 
Join Date: Jan 2012
Location: Somewhere, yet nowhere
Posts: 1,739
Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice Drcoffee is just really nice
Quote:
Originally Posted by AuSeeker View Post
I don't believe that is correct, I don't have a "vacuum drum" on my 2004 That I have ever seen, or a vacuum line either, I will look closer when I get the time hopefully tomorrow or the next day.

Also a "vacuum drum" is called a vacuum booster and it also doesn't show up when looking at online dealer parts website in the diagram of the brake system.
You are correct. My mistake.
__________________
2007 4Runner Sport 4WD 4.0L 228,000 miles
The real stats on gun murders in America compared to the world (link)
Good riddance to the Clinton Crime Family--> I Voted TRUMP…how’s it going for you now Trump is gone? Be careful what you ask for. You may just get it.
Drcoffee is offline   Reply With QuoteReply With Quote
Reply

Tags
fluid , light , needing , pads , rear

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
“BRAKE”! Warning in Odd Situation RichinRidgewood 5th gen T4Rs 4 07-24-2021 10:13 PM
Transmission Fluid (tricky situation) (muddy fluid) hairpin 3rd gen T4Rs 16 10-31-2020 09:25 PM
Unique Brake/Wobble Situation jbssfelix 4th Gen T4Rs 4 05-16-2016 11:42 PM
Brake fluid/dash light situation/ fluid level FlaskTL 5th gen T4Rs 19 06-03-2015 10:53 PM
Brake fluid, transmission fluid, and rear differential fluid NViejeP 4th Gen T4Rs 12 03-31-2007 03:43 PM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 11:28 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
Feedback Buttons provided by Advanced Post Thanks / Like (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
***This site is an unofficial Toyota site, and is not officially endorsed, supported, authorized by or affiliated with Toyota. All company, product, or service names references in this web site are used for identification purposes only and may be trademarks of their respective owners. The Toyota name, marks, designs and logos, as well as Toyota model names, are registered trademarks of Toyota Motor Corporation***Ad Management plugin by RedTyger
 
Copyright © 2020