Provided the brake calipers are all bled correctly and the brake job was done okay the next step for me would be to bleed the master cylinder. Many do not do this step but it can be crucial to getting a good pedal if any air was introduced into the system when doing the job. Here is a .pdf mentioning this it is detailed in step 4. This helped return a friends Sienna braking to a good pedal after he had unknowingly introduced air into the system when he let the fluid in the master cylinder get low when bleeding the wheel brake calipers.

View attachment Brake Bleeding.pdf

 

Holmes,
That van should not be driven like that for one day, let alone several years.
Get it fixed before you kill someone.
Seriously, Dude.

 

FYI- Just in case you've never heard of it, or checked for it:

It is rare, and I have only seen it before on other cars, but a failing rubber brake hose can display similar symptoms. If the hose has lost its structural rigidity, and thus allows expansion within itself (i.e "balloning"), hydraulic pressure that would otherwise be applied to the calipers is lost to the effort of expanding of the hose. In general, I agree with the sentiment that it is not safe to be driven until fixed.

$.02

 

When you did the brakes, did you verified that the slide pins allowed the calipers to slide in and out with respect to the caliper bracket? When I bought our 2004 Sienna XLE there was hardly any braking action when I stepped on the brakes. Took the calipers off to inspect the pads, and notice that all the pins were frozen. Free up the pins and now the brakes stop the minivan on the proverbial dime.

 

Consider replacing the master cylinder and then bleeding all 4 wheels.

As mentioned, you must bench bleed the master cylinder prior to installation.

 

In extreme cases bench bleeding can be the only option. On the early model Sienna's 2004-2006 ( i don't know about later models) Toyota has thoughtfully provided a bleeder nipple on the master cylinder assembly. There is a procedure to actually bleed the master cylinder on the vehicle. It is partially described in the .pdf provided in the 2nd post, step 4 in the .psf attachment provided details this

 

On the early model Sienna's 2004-2006 ( i don't know about later models) Toyota has thoughtfully provided a bleeder nipple on the master cylinder assembly.

Convenient :smile:

 

Rather than depend on someone else to help me do brake bleeding, I use a Mityvac vacuum bleeder. Easy to use, and seems very thorough. I also believe that it is necessary to activate the ABS system when doing a thorough bleed. If you have the right OBD tool, that is one way, the other is to go on a slippery road surface and brake hard.

I do agree with the suggestion that the master cylinder must be bench bled. If it has a bleeder nipple, the vacuum bleeder should work.

If you do decide to go with a vacuum bleeder, remember to start with the cylinder closest to the MC, ie the left front. Move then to right front, then left rear, and finish on the right rear. This is also a good way to flush the system, as it is very easy to see when the old fluid has been fully purged out of the system, and the clear new fluid starts to come into the hose.

 

...
If you do decide to go with a vacuum bleeder, remember to start with the cylinder closest to the MC, ie the left front. Move then to right front, then left rear, and finish on the right rear. This is also a good way to flush the system, as it is very easy to see when the old fluid has been fully purged out of the system, and the clear new fluid starts to come into the hose.

Rick, is there any particular reason why vacuum bleeding should require the complete opposite sequence from the normal recommendation?

 

Goodtogo: You know, I read that on another automotive forum a couple of years ago(GMT 400 Pickups), and it worked well for me. Never questioned the reason, just did it. I'm curious now as to the rationale. Hope someone else chimes in.

I had a Mityvac, and the brake-bleeding accessory group, and I was tired of trying to train my wife to push down, when I said down, and let the pedal up, when I said up.

I should have mentioned that vacuum bleeding requires that you remove the bleeding nipples, and wrap the threads in teflon tape, otherwise the vacuum pump can draw air down the threads and disrupt the process.

In a perfect world, I'd get a proper pressure bleeder, but I'm already overloaded with tools...

 

Goodtogo: You know, I read that on another automotive forum a couple of years ago(GMT 400 Pickups)

In my opinion, it's probably best to stick with Toyota's recommendations regarding wheel bleed sequence.

 

Just wondering what else Toyota recommends. Do they mention vacuum bleeding? Can you point me to the info from Toyota, as after all, doing brakes correctly is very important.

 

Tinkindling - Rick is right on target - the ABS system is where you have the air. You need to push the air out of the entire system - some people back feed the brake lines - bubbling up to the master cylinder - this in my opinion is the best way to get that unit purged of air. You will not only purge the ABS - but the master cylinder as well.

 

I solved my squishy brakes. I also have been fighting squishy brakes and have bled the system using Toyota's method and it doesn't last, maybe a few weeks. It was time to start changing out major parts. I was in the process of changing out the brake booster when I decided to back bleed the master cylinder using Phoenix System Reverse brake bleeder which I had used previously on all brakes but never the master cylinder. Since I had removed the cowl to remove the brake booster it was pretty straight forward. Connect the hand pump, crack the bleeder and pump away. Since I was there, I went ahead and changed out the brake booster valve since I had it, but I did not change the brake booster. Well, it's been 3 months and the brakes are still nice and firm!

 

Four year old post. Where did the original poster go?

 

OP last seen Jun 29, 2018

 

I often wonder how many people show up here with their new-to-them Sienna, ask a question or five, sell the Sienna after 1-2 years, with some lingering problems that they never fixed, then the new owner comes on here with their new-to-them Sienna (now 1-2 years older) and asks the same questions as the previous owner. There was a 2004 a few years ago that I'm almost certain popped up twice more with new owners with the same exact problems that had been posted originally (same State with the same conditions). One even found the old thread and revived it with something like, "I'm having the same issues. What was the fix?"