Brake Pedal Hiss...stuck caliper

My son's 03 Sequoia's brake pedal is "hissing" on occasion. It seems random and occurs while holding the pedal pushed in and then continues for a second or few after taking foot off the pedal. Fluid level is good, braking seems fine, and I don't feel anything different about the pedal when this occurs.
Any pointers would be greatly appreciated.

 

Sounds like a bad booster. How many miles are on it?

There is a test in the service manual for the booster. I'll see if I can find it but the gist is that with the truck off, the brake pedal is pushed a few times. It should build pressure then get so firm you can't press it any more.

 

Also, at the 10 o'clock position (IIRC) on the booster should be a one-way check valve with a vacuum hose over to the manifold. Inspect the valve is fully installed and its grommet isn't toast. Inspect the hose, that it's plugged in on both ends AND it's not cracked.

 

Brake booster test

 

Thanks @FirstGenVol and @shifty`
It has 175k and I'll check both of those things this evening.

 

Ok, I’m confusing myself, what exactly are my results saying?
Test 1- When off, and I depress 3 times, the 1st goes down the usual pedal travel and then the next is less, and the 3 doesn’t go in at all. Feels like it’s building holding pressure.
After the 3rd press, while holding in then starting the pedal gives/moves away from the foot.
The second test seems to build and release the pedal pressure the same.

 

If I'm understanding you correctly, that sounds like what should happen. Do you hear any hissing in the process?

I'm trying to think what would make a hissing sound, but drawing a blank. And you're sure it's not something stuck in the caliper, none of the 4 pads are worn, none of the 4 shoes are worn?

 

Yeah that’s what I thought, it’s doing what it’s supposed to, but definitely hearing hissing when pushing the pedal in and on occasion the hissing continues while holding/then releasing the pedal.

Not sure if, but don’t think they are, if any of the pads/calipers are sticking but will jack it up and give the wheels a spin to check tomorrow.

 

I vote brake booster as well despite the tests being okay. My wife's van had hers go out recently. Started out as a low level hiss then slowly got worse over time to the point that the brake pedal actually would push back a little when you pressed on it. Not a nice feeling. Swapped out the booster, bled the brakes (since I had to remove the master cylinder to remove the booster) and good to go.

 

I mean, if you heard hissing while doing this, I suspect the booster is bad, you have a leak (booster seal, internal), or that check valve (and/or its hose I mentioned) is cracked/leaking.

I guess the check valve is what I'd be checking next. I presume he has one? Here's a pic from an '05 DC which should be close. Check valve is circled.

The check valve has a rubber grommet that holds it in. Spray soapy water all over it and its vacuum hose, then have the kid repeat the test while you watch around the valve. Do you see any soapy bubbles? If not, the problem is probably inside the booster. You may be able to audibly confirm while there, if the sound is coming from the booster. That would be some really good info to have.

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The check valve is there and hose looks good. The value does wiggle a bit, but I like the soapy water test and will try tomorrow.

Just a bit freaked out by the issue since he’s a new driver, so he’ll be driving the Gen 2 Tundra until we get it figured out.

I did check on boosters and it seems like there aren’t any OEM’s available and rebuilt might be the only option. If anyone has a preferred option let me know.

Thanks again to all for the help. I’ll report back once I test a bit more.

 

No air leaks around the check valve per the soapy water test.
I drove it a good bit yesterday and it did not hiss, and the more I read the test procedures it seems to be testing normally. Obviously, something is going on and my son says it mainly occurs while sitting at a light or in traffic, so during elongated pedal holds.
Normally I'd just replace the booster but they aren't easy to find and Autozone may be the only option, so not thrilled about that since I prefer oem.

 

Is OEM not available for the truck? I'm just remembering the problems the last couple of guys had buying from the LAPS.

 

All of the oem places say out of stock
Even RockAuto, Napa and Advanced say out of stock.

 

I think the OEM booster was discontinued a while ago for our trucks. Same with master cylinder. I'm still not happy with Toyota.

 

Damn, I guess I should probably buy one for my truck, before they discontinue mine too?

Looks like they sell a lot of peripheral parts for my '06, or the whole booster assembly with new check valve etc. for around $400 MSRP if I purchase from Japan, but if I buy domestically the damn thing is just shy of $1,000.

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https://parts.lakelandtoyota.com/p/...er/3968279/446100C041.html?partner=googlebase

If this is it, that's an insane price

 

How much is shipping though from Japan?

 

It's actually really cheap. I recently tried ordering a part from the same website and shipping was around $12. They let me place the order and then later came back and said the part was no longer available.

 

What website are you using that’s translated to English? Sounds like a nightmare if you get a defective part.

Some kid is going to email you that his Dad committed hara-kiri if he’s responsible.

 

@shifty` is the one that recommended it.

https://www.amayama.com

 

I thought all our parts were made here. Is that not the case? Weird.

 

That’s it, I’ll check to see if it’s in stock, but I doubt it is.
And yeah the price sucks! Even the remans from auto parts stores are $500+

 

Amayama sources a significant amount of parts from Japan, and ships from Japan. All genuine OEM. You'll pay far less, but shipping isn't friendly, nor communicative. But it's one of those "hidden secret" ways for genuine OEM parts sourcing if there's nothing here and shipping isn't horrible.

 

It’s gotta be a shared part to something other than the Tundra since only the Tundra is made here.

 

Plenty of the parts for our trucks are made in Japan and four other countries. There are two-letter country codes for each on the little red'white Toyota sticker when you buy parts.

Plenty of parts are also shared across models, and we have at least 1 member here in JP with a 1st Gen Tundra.

 

I drove it all last week and couldn't get the pedal to "hiss" again, so this morning I took it to my trusted Toyota specialist and he said to wait. The testing I had done was basically what they do and I be wasting money if its not showing any symptoms. We did discuss the oem booster availability and he put in a call Toyota's southeastern distributor, and will let me know what he finds. To be continued....

 

I tried this today. The couple of parts I bought were HALF of the price at Ourisman (McGeorge), BUT, the shipping...was LESS than Ourisman (McGeorge)!! Somehow they can ship from Japan cheaper than Richmond VA. I'm curious to see how long it takes.

This could work out OK for many items. A lot of what I buy is "just in case", or "I'll get around to this eventually", so a longer wait for substantial savings may be a good trade off.

 

General consensus is 2-6 weeks is the normal range. And I did read a couple people say they failed to get a tracking notification, but it seemed to be a minority.

 

Just noticed the front passenger wheel is coated in brake dust and all the others are clean! Sticking caliper?

Edit- Son said he could feel it dragging