Brake Issue

A couple of months ago, the brake light in my 290K 2001 came on. Firm pedal, stopped well and straight. Only issue I've had is the rears seem to lock up easy. I checked the fluid level and it was at the low mark, so I topped it off. The light went out and I hoped it was due to pad wear.

A couple of weeks ago it came on again, and the fluid was low again, so I dug deeper for leaks. I crawled underneath to look a the lines and found the backing plate on the LR was wet. Assuming a bad wheel cylinder, I ordered a rear brake kit - new shoes, drums, hardware ad cylinders.

This weekend I put it all on. (Well, almost all. The LR cylinder was definitely leaking, everything was wet inside. The RR was fine, so I left it alone.) I bled the LR the old fashioned way, by having my daughter work the brake pedal while I opened and closed the bleeder. Once I got two clean shots with no bubbles I called it good.

During the test drive the brakes that had felt good, despite the leaky cylinder, were now terrible. Lots of travel before any resistance or actual braking and standing on them will stop the truck (eventually) but wouldn't lock any wheels. Pumping the pedal brought better feel, but not more stopping power. The pedal doesn't sink to the floor, but it's soft and low.

It seems I fixed the obvious problem, but either created or discovered another. Thankfully, this is my backup vehicle, so it can sit while I sort it out.

I double checked no visible fluid at the new wheel cylinder. There is no noticeable loss of fluid at the master cylinder.

My theory is that I've also got a bad master cylinder and that the bleed process ran the M/C though a greater stroke which further damaged the already deteriorating internal M/C seals.

I also have a sweet exhaust smell, particularly at startup, with a slight white smoke. I understand that can be indication of a bad M/C and brake fluid getting in the booster and sucked into the engine.

My plan is to bleed the LR one more time to be sure, but if that doesn't improve things order a new M/C, but I'm open to alternate suggestions.

 

My bet is the master cylinder went bad. I had some similar symptoms on my 03 Sequoia. The dealer told me the ABS may be bad or the booster. I decided to change the master cylinder and that did the trick. But the Sequoia is a little different than the first GEN Tundras. If I remember correctly, there’s been a few threads throughout the years and you may have one of the extra funky master cylinders. Let’s hope it didn’t get into your booster and ruin it.

 

@salguod you might still have air in the system. These trucks can be a real pain to bleed. It can take a long time. Did you remember to bleed your prob valve? It's near the spare tire.

Also, I experienced something similar and part of the issue was air in the ABS. I had to find a stretch of gravel and lock up the brakes to engage ABS which purged some of the air.

 

Yeah. Its recco’d to put a 2x4 under the pedal to keep pedal from bottoming out and blowing things in the MC. This may be the case with yours. It happened to another member here not too long ago.

You could also still have air in your system trapped up in the LSBPV near the spare tire. You could bleed that now (or again) that its been driven. I’d start all over again and bleed the entire truck.

Might be smart to replace the DR Cylinder since things fail in pairs to save you future aggravation seeing as you need to bleed again.


Hope you didn’t blow your MC.

 

Be sure that your rear shoes are adjusted correctly with the star-wheel adjusters too.

 

I find it very unlikely that I'd get air in the system beyond the left rear wheel cylinder. It's the only place the system was opened and only a couple of minutes. To get air up stream of that would require draining a lot of fluid to make room and that didn't happen.

No ABS on my truck, so that won't complicate bleeding.

Shoes were adjusted to create a slight drag. I also made a couple of hard stops in reverse after to try to activate the adjusters.

Didn't know about the 2x4 trick, I'm going to search for it but if anyone has links to more info, I'd appreciate it.

 

Air would make it to the load sensing proportioning valve (LSPV). It's on the left side of the frame above the differential.

 

Basically cut and install some 2x4 (or anything that will block) under the pedal to keep it from being pushed farther than it normally goes during operational driving/stopping.

Since you’ve adjusted and sound like you’ve covered most bases then its probably air or MC Mangles.

When I rebuilt my Drum Cylinders, I reused the old cylinder and just replaced the pistons. Lots of air was in the system, but unlike your scenario it was open for a while as it was lots of work. Basically bled a full 32oz sacrificial bottle of DOT3 through and then followed up with a full tin can El Supremo Fluido Bosch DOT5.1.

 

That may be the issue. Try adjusting the star wheels until you can’t turn the wheels, then back off until you’re left with a slight drag. Probably 3 to 5 knotches back. You’ll want to use a pick or something to hold the self-adjuster lever away from the star wheel when trying to back them off.

 

Well, here we are almost a month later and I'm finally getting around to replacing the MC. Decided that, assuming it's original, at 20 years and 290K, it's not a bad idea. Besides, in doing that I'd end up bleeding the system anyway, addressing both possible issues.

Bench bled the MC with no problem, installed it with no problem. Bleeding the system, however, was problematic. I'll spare you the details, but I had 3 wheels with what I assume were frozen speed bleeders. No fluid would come out, either by vacuum or pumping the pedal. Several bleeding sessions, a fair bit of time on Google, some angry words, 3 new bleeders and 32 oz of fluid later, I was done. Or so I thought. I now have a decently firm pedal, but a lot of travel before the brakes bite and barely enough stopping power to lock the wheels on my gravel driveway.

The fluid that came out of the old MC was very black, nearly opaque black. The fluid that came out of the rear bleeders looked fairly new - slightly dirty yellow, the fronts a very dirty yellow. That indicates to me that the MC rubber internally was deteriorating, or at least that's what I'm telling myself to justify that replacing the MC was the right thing to do.

I'm not sure what to do now. The next thing to consider is the booster, but I'm not sure if my symptoms fit with a bad booster. Time for some Googling.

Thankfully, this isn't my daily, but I did buy it to do work and I've got a bunch of truck work waiting on getting it back on the road.

 

May need to find a dirt or gravel road to activate the abs on and then re-bleed the system. Could still have air in the system.

Did you do all 4 corners and the lspv above the rear diff?

 

No ABS on my truck and yes, I bled all 4 corners plus the LSPV. I went RR, LSPV, LR, RF, LF.

Reading some more I think I need to recheck the adjustment of the rear brakes. I adjusted them to a "slight drag", but that's pretty subjective, maybe they're too loose. That makes sense as it would allow excessive travel before the shoes bite.

Also, I understand that it's not braking in reverse that activates the adjusters, it's the parking brake. I have not used the parking brake yet, I'm a bit concerned to try it given the mileage. However, the cables may have been replaced with the frame and may be newer. Anyway, I want to check the parking brake cables and activate it to properly adjust the drums.

 

It should go in this order: rr, lr, lspv, rf, lf.

Sometimes you need to step on the brakes to 'seat' the drums and then continue adjusting them.

 

OK, I'm getting there.

The rears were no where near adjusted properly. I'm not sure what I was thinking when I thought it was good before, it clearly was not. My parking brake cables have a lot of slack, so I wasn't able to use the parking brake pedal, but the bell cranks are free and I was able to pull them and actuate the adjusters. (Fixing the parking brake cables is a job for another day, preferably not a week night.) I pulled each a bunch of times, until I no longer seemed to hear the adjuster click (it was hard to tell) and when a single pull of the cable would stop the rotating wheel.

Took it on the road and it's much better, but not quite where it should be. Pedal travel still feels long and hard braking gets me chirping of the fronts, but no lockup. On my gravel driveway, the fronts lock, but the rears do not. I'm wondering if I've got more adjusting to do.

Bigger problem is the pulsing. Good grief, it's bad. Like shake the whole truck bad. There was none before I started this, and the only parts I changed were the rear. I bought an inexpensive Centric complete kit from Rock auto and I suspect I'm a victim of cheap parts. Everything but the RR wheel cylinder in the rear is new, nothing in the front is new. I'm going to pursue replacement rotors from Rock Auto, we'll see how that goes.

 

If you saved your old drums, maybe you could have them turned and then reinstall. They have the little weighted balancer on them that keeps the bad vibes away.

 

I wish I had, but they're long gone. I'm not quite convinced the drums are the problem, but I'm not sure what else could cause this pounding.

 

You’ll figure it out.

 

Read too many stories of pulsing with Centric drums on Tundras, so I decided to just order new ones. They arrive Wednesday along with a new parking brake cable. The old has a lot of slack in it, seems unlikely that I'll be able to adjust it out. Checked the frame replacement work order (from 9/2010 at 160K) and bell cranks were replaced, but the cable was not, so that cable is 20 years and 290K miles old, it's due.

Next weekend I'll install everything, hopefully that'll fix it.

 

Good call on this.

 

Replaced the Centric drums with AC Delco parts this weekend and replaced the parking brake cable and I'd say I'm at about 90% now. I still cannot lock up the brakes, but they do chirp so I'm at the friction threshold. The pulsing is gone, brakes straight and smooth.

I had determined that I probably could adjust the old one, and planned to to avoid what I knew would be a broken retaining bolt somewhere, but the adjuster was too rusted. Sure enough, I broke one and spend an hour drilling it out so I could put a new bolt in.

It probably took another 20-25 pumps of the parking brake to get the drums adjusted to this 90% level. At first, the parking brake pedal went to the floor and it wouldn't hold the truck while at idle in Drive, now it doesn't drop that far and it will hold it. I imagine a bunch more applications and I'll be all the way there.

Very surprising how much effort it takes to get these drums properly adjusted.

 

Some parts of this thread pertaining to the ‘Equalizer’ might be helpful for you.

https://www.tundras.com/threads/adjusting-rear-drums.62519/

 

I've read that thread and used it to do my cable adjustment. I put on a new cable which included the "equalizer" attached to the diff. The old one was frozen. It did not include new bushings or the screw, so I had to reuse them. They were in decent shape, I cleaned them all up and applied brake grease to all. I intend to use the parking brake often to keep it in good condition.