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Discussion Starter · #1 ·
Hi All -- We have a 2008 AWD limited and have noticed the brakes are feeling a bit spongier than normal. Brake fluid is up to level and there are no lights on the dash. So we took it to our mechanic who said we needed a booster and master cylinder -- $2100. Wanting to be sure we took it another well-known Japanese shop (in Seattle) and THEY said it needed pads, calipers, etc. -- but nothing about a booster and master cylinder -- also to the tune of $2100. So to "break" the tie we took it ANOTHER Japanese shop who said everything was fine, pads were at 30% and we shouldn't worry.

So folks -- any suggestions? Do we take it to a FOURTH mechanic? Are Sienna brakes just generally spongy? We've had the car since the end of January but my wife even noticed a difference since we got it. I would appreciate any help. Thanks.
 

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2006 Sienna XLE with NAV 225k miles
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Do a brake fluid bleeding first before you go to another mechanic for second opinion. It’s a easy DIY.
 

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If the brake fluid doesn’t look like it’s fresh out of a new bottle, might as well flush the fluid while you’re bleeding. Without letting the reservoir go dry, keep bleeding until clean fluid flows out of the caliper/wheel cylinder. You can make quicker work of it by drawing old fluid from the reservoir then filling with fresh fluid before bleeding, but I don’t know if fluid can be drawn through the goose neck or if it’s worth pulling the cowl to get to the main reservoir section.

Any recent panic braking? There’s a school of thought that going easy on the brakes along with keeping brake fluid more than a couple of years can lead to corrosion in the far reaches of the master cylinder bore. One day you put all you have into the pedal and the piston goes into to corroded section tearing the seal. The brakes still work but firm resistance is gone, or at least occurs after more pedal travel.

Sixto
‘04 LE FWD 191K miles
 

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Discussion Starter · #5 ·
That sounds reasonable. Again my problem is that I’ve gotten three totally different diagnoses. The consensus here seems to be brake fluid/master cylinder issues. I’m not very DIY so would rather have a pro do it. Thanks!
 

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I have to say that I was never impressed with the stock brakes on my 2010 AWD van. Granted, I tend to push her harder than most, but I still felt the brakes were borderline adequate for the job even in perfect form. The solution was to upgrade the front brakes to the 3rd gen version. It is a fairly simple, straight forward, and inexpensive conversion to do, and the results are truly significant. There are threads here which cover the conversion if you are interested. After having done it myself, I would not own one of these 2nd gen vans without the swap. It's that good.
 

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Do 16” wheels fit over gen 3 brakes?

Sixto
‘04 LE FWD 198K miles
No, I don't believe any 16" OEM wheels do, but the OP should have 17" wheels which do fit, providing the wheel weights get moved away from where the barrel and caliper are closest.
 

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That sounds reasonable. Again my problem is that I’ve gotten three totally different diagnoses. The consensus here seems to be brake fluid/master cylinder issues. I’m not very DIY so would rather have a pro do it. Thanks!
My vote is for a 4th mechanic. Find a trustworthy place, preferably with an old mechanic that actually knows things rather than a young technician who can follow a diag-chart. This is NOT a Japanese-centric issue. This is a brand-agnostic issue with brakes. They all work the same. The only real differences is if they need a special tool to retract the caliper pistons or whatnot. Taking it to an actual Toyota dealer isn't a totally terrible idea either. Whoever you take it to, though, DON'T tell them the current diagnoses you have.

For more detail, your diagnoses:
1) we took it to our mechanic who said we needed a booster and master cylinder
2) THEY said it needed pads, calipers, etc.
3) ANOTHER Japanese shop who said everything was fine, pads were at 30%


Right off the bat, #3 is totally discredited. You have a problem (the brakes are soft and getting softer over the last 6 months). They said everything is fine. Everything is NOT fine, so their diagnosis is false. That said, I would say that #3 cancels #2 out and discredits them too. If pads are at 30% (mm of pad thickness would be a better value here), then the shop that said pads are bad is just quoting a brake overhaul assuming it will fix the problem. Additionally, a shop that says you need calipers is probably trying to scam you over-quoting work, unless they are obviously leaking. A brake inspection involves putting the van on a lift, pulling the wheel and looking at the brakes. There's never any disassembly done, unless you've authorized work. Some places don't even bother to pull the wheel. They just look through the spokes. Although, I will say, if the calipers ARE leaking, it's possible they are quoting pads because they believe them contaminated with fluid. A booster and master cylinder seems like the nuclear option here. Spongy brakes are almost always air in the line (from a leak) or moisture in the line (from age) and the first step is to check all calipers for leaks and, finding none, do a full fluid flush. You've only had the van for 6 months. A small leak might not be revealed in a dropping reservoir. It's also possible that the previous owner HAD a small leak and replaced something but didn't get the air all out. It's entirely possible that you may need calipers, pads, rotors, a master cylinder and a brake booster and other work done. However, a fluid flush will probably cost less than $100 and any mechanic could do it for you. Just make sure to ask for a proper inspection of the calipers to make sure they aren't seized and/or leaking. Asking them to clean, polish and lube the slide pins (@3Wheelerguy's suggestion) is an excellent idea too. If it DOES need anything new, you'll have fresh, clean fluid already in the system.
 

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Discussion Starter · #12 ·
Thanks for all that info! Of the 3 shops I have brought it, one was an established older guy, the other two reputable, established long time Japanese car-only mechanics. That's what's frustrating. I believe all of them took the wheels off. I think I'm going to start small and do the brake flush and see where that takes me. Thanks again.
 

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FWIW, having owned both for close to a decade now and having changed the brakes on both, I prefer the 2nd gen Ody brakes to those on the 2nd gen Sienna; the pedal depression is much greater on the Sienna, which is unnerving when moving from one vehicle to the other. Ours is an AWD too, and I've never bled the brakes; just pad changes.
 

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Discussion Starter · #14 ·
My daughter has a 2007 Odyssey, and I find it a far superior vehicle in terms of driving dynamics and overall fit and finish. But my wife wanted an AWD van so choices are limited.
 

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One additional suggestion - take a flashlight and examine the brake pads yourself, through the wheel Easy to do (once you figure out what you're looking at) and you can then (roughly) confirm how much pad is remaining. 30% pad remaining would be approx 5mm of pad material, which is roughly the thickness of the backing plate. That might help confirm the accuracy of some of your estimates.

I also second the comment about the stuck slider pin. After I had a panic stop to avoid a deer and the brakes didn't work to my satisfaction, I replaced pads and rotors and found that the slide pins on the front brakes were stuck - the lubrication had dried up over the few years since the brakes were last replaced. Re-lubricating everything (as well as replacing with upgraded performance pads and rotors) yielded outstanding braking.

Having said all that, spongy pedal feel is more likely to be fluid related - either air in the system, old fluid, seeping bleed nipples, or failing master cylinder seals. I agree with others to replace and bleed the fluid first to see if that resolves the issue.
 

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This may sound odd, but bear with me. I had a 2008 Dodge Avenger that had soft brakes since new. Not really bad, but enough that I often would double-pump them to get a firmer pedal. I took it to the local dealer, who said that the pedal feel was normal. I bled the brakes more than once with no real improvement, and drove the car like that for awhile. One day I was futzing around online, and found a thread about how a person had the same issue, and was told by a local mechanic to try this: drive into a gravelly area at moderate speed, then hit the brakes hard enough to activate the ABS. Do this a couple of times. The OP said it really firmed up his brake pedal feel, so I took my Avenger out and tried that technique, and it worked like a charm! Brake pedal feel was MUCH firmer. I mentioned this to a friend who has owned an auto repair shop in the past, and he said that he had done the same thing with another brand of car, and had the same good result. Now, in these cases, the brakes were disc all around, but if that is what your Sienna has, it might be worth a shot. I have a 2015, and so far, the brakes a re very firm and work very well, but if the pedal started getting a bit spongy, I'd try this technique before spending a lot on brake work. No guarantees, YMMV, legal yada yada, but it has worked for me and others.
 

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I'm in the camp that says change the brake fluid--if it is old. I ran my 2014 to 89,000 miles before the first brake fluid change. After that the brakes were noticeably firmer. By the way, $2100 for pads, rotors and calipers is outrageous. Whatever you do, throw out that opinion.
 
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