2008 4runner Master Cylinder piston, I found the part # and fixed it!!!

[bwwwalker]

I have a 2008 4Runner and the brake pedal was sinking whenever I would come to a stop. Toyota wants you to change the entire Master Cylinder with a list price on the part being almost $3000!!! Plus the labor on top of that. Toyota does not list the part number for master cylinder piston sub assembly so I found a site that listed the master cylinder piston in a 2010 through 2017 and took a chance and ordered the part and rubber grease needed. This fix is a perfect match and the brakes feel like new again. You do NOT need to go to Toyota to bleed the brakes after. There is a really simple and quick way to bleed them which I will detail at the end.
Parts needed are:
Toyota part number: 47026-60090 Piston Sub-Assy

I also ordered the rubber grease for the seals:
Toyota part number: 08887-01206 RUBBER GREASE, 100G

The steps to change are as follows and wasn't as bad as I thought it would be for an average garage mechanic.

***NOTE The warning to disconnect the battery and wait 90 Seconds after disconnecting the battery or risk setting off the airbags.***

Once it's out you need to measure the linkage with a tape measure because you will need this when you put it back together. Pry off the rubber boot.

To get the piston out, you need to remove the C-clip retainer. The repair manual shows how to remove the c-clip holding piston seal

But I found a 3" piece of pipe worked like a charm in a big C-clamp. This removed the pressure off the seal needed to remove the C-Clip. Once the C-clip is out, simply give a good pull on the piston to remove it.

Apply the rubber grease to all the rubber seals and reassemble.

Be sure to set the length of the linkage correctly before you install it back in the vehicle in reverse order.

Before connecting the brake lines to the master cylinder, pump the brakes to move fluid to the brake line connector.

Once the middle two start to pushing fluid then follow the brake bleed process.

When I bleed brakes, I use a 3/8 clear hose run into a clear jar. Put the key in the on position causes the break booster to run, then break the bleeder on the front right and watch for air as you have your buddy touch the brake peddle. Then bleed the front left. Followed by the rear right and then left.

The process is listed in more detail here:

Message me if I've missed anything or anyone has any questions.

 

[Supersonic]

But I found a 3" piece of pipe worked like a charm in a big C-clamp. This removed the pressure off the seal needed to remove the C-Clip.

To clarify, the piston gets compressed in to removed the pressure off the seal, then the c-ring is easily removed using another screwdriver. Thanks for this write-up, it's hard to see the c-ring but if that's the most difficult part after removing the master cylinder, you've saved thousands for those who repair this themselves.

Couple of question, though if I ever take one apart it would become obvious, I haven't digested the problem completely, but if I understand it is the piston o-rings have worn down? What is the piston made of? Looks like an o-ring on each end? Is the first picture of 2 pistons a side by side comparison? The new one the lower one?

Here's the Lexus page for reference too;
https://www.lexuspartsnow.com/parts/lexus-piston-sub-assy-bra~47026-60090.html

 

[bwwwalker]

To be able to remove the C-clip, the plug on the end needs to be pushed back in a little bit. No matter how hard I pushed, the plug was not moving. I tried to push on the piston and the plug at the same time and it wasn't moving so I tried the piece of pipe 3/4" X 3" in a big C-clamp and this removed the pressure off of the plug and I could then easily remove the C-clip. After the C-clip was removed, a good solid pull was needed to remove the plug and piston all together. I had to put the nut back on the threaded end and grab the nut with vise grip pliers.

I also used the piece of pipe and big C-clamp when I was installing the piston and plug it to hold the plug in place while installing the C-clip.

The picture with the two pistons shows the original on the top and the replacement on the bottom. There was very little evidence of the external rubber and plastic seals being worn but there are also internal seals within the piston that were clearly worn when I would try and move the whole actuator within the piston assembly.

Here is good place to get the part:

https://www.toyotapartsdeal.com/oem/toyota~piston~sub~assy~bra~47026-60090.html

I hope this helps someone. I’m really glad I swapped out the piston for a couple of hundred bucks as opposed to paying Toyota $4000!!! Knowing what I know now, the whole job would only take a couple of hours. I think I was closer to 3 and a half hours because it took a while to figure out how to get the piston out and I didn’t measure the linkage distance originally so had to take the whole unit out a second time to adjust the linkage length to get the brake pedal set correctly.

 

[earthrealm]

@bwwwwalker, wow this is super super.
quite impressive.

the leaking piston is the chief culprit for most of the abs/mc failure, as the leakage makes the electric pump to overwork/actuate continously...and thus burn out.
my replacement abs unit is on its last legs now..as it actuates every time i depress the brake pedal..and i hear a slight whoosing sound when i depress the pedal , all which point to a vacuum leak in the mc assy, and the pump working overtime to maintain pressure.
[MENTION=66389]BlackWorksInc[/MENTION], i think you better add this thread to the brake assy sticky information pool

 

[Nolaninthebox]

Recently replaced my master cylinder contraption on my 05 4Runner. I have the old mc piston out and I was curious if anyone has purchased one for a cheaper price than the $100+ from Toyota? Thanks

 

[AuSeeker]

Recently replaced my master cylinder contraption on my 05 4Runner. I have the old mc piston out and I was curious if anyone has purchased one for a cheaper price than the $100+ from Toyota? Thanks

You can find the same piston sub-assembly the OP used for his 08 model a bit cheaper on eBay, if it will work in your 05 model is a risk you would have to take.

https://www.ebay.com/sch/i.html?_fr..._nkw=47026-60090+Piston+Sub-Assy&_sacat=33566

 

[rwmille]

You can find the same piston sub-assembly the OP used for his 08 model a bit cheaper on eBay, if it will work in your 05 model is a risk you would have to take.

https://www.ebay.com/sch/i.html?_fr..._nkw=47026-60090+Piston+Sub-Assy&_sacat=33566

Just curious if anyone ever confirmed whether this part is compatible with earlier 4th gen 4Runners. I own a 2006 with this issue, and am trying to find some alternative to a $4000 repair cost.

 

[UrbanRunner651]

I own a 2006 with this issue..

OP has an 08. 06-09 are all identical in the engine bay so you should be fine. I would assume as AU pointed out that the earlier 4th gens should be a direct swap as well.

 

[earthrealm]

[MENTION=127215]bwwwalker[/MENTION] so the part has come in from partsouq uae, gotta tackle this ops in a few days.
any final tips to make the job easier?

 

[AuSeeker]

[MENTION=127215]bwwwalker[/MENTION] so the part has come in from partsouq uae, gotta tackle this ops in a few days.
any final tips to make the job easier?

Just an FYI, but looking at [MENTION=127215]bwwwalker[/MENTION] profile he hasn't visited the forum since last June so not sure if he will respond.

 

[bwwwalker]

I tried to make the instructions as complete as I could think of. Be sure to have a the pipe and c-clamp needed before or some copper pipe with a pipe cutter so you can cut the pipe you will need to take the pressure off of the c-clip holding in the piston. Once the C-clip assembly is out then a solid pull on the piston is needed to pull it out.

** Measure the linkage distance as I tried to show or the brake lights won’t work correctly.

Have a clear bottle and clear tube for bleeding the brakes one at a time. The brake booster pushes fluid when the key is in the run (without the car started) and you press the brake pedal.

Message me if you need further instructions.

I hope this helps.

I thought it was crazy that Toyota wanted me to spend thousands for a simple fix so I wanted others to have the information they needed to fix it.

Cheers

Brent

 

[Silvr]

Its 2022 and this thread is still relevant. I had the infamous brake accumulator squeal and attempted to fix the issue with a new accumulator. I bought one from Dubai of all places on ebay for $760. I figured this was better than buying a new master assy.

It worked for a few months, and then returned. I stumbled upon this thread and bought the part from Japan. $65.

NOTE: The white gasket on the piston rod has a diagonal slit in it. This is per design. I asked the seller on Ebay to confirm if this slit matched their inventory. They accused me of mutilating the seal lol. Ebay awarded me the $65 for receiving a "damaged" part. I took out the old piston rod and it has the same slit lol.

Anyway,

I replaced this piston rod with the instructions here minus the clamp, I had my wife help me instead lol. Old unit had no visible damage. But fired her up and the squeal was gone! Bled the brakes and shes braking better than ever!

Thanks!

10/8/22 Well, here's an update. This repair didn't not solve the issue. Squeal came back after a month lol.

I ended up having to buy a whole new master cylinder system for $1100.

Everything is well and running like new. If only I changed the whole assembly in the beginning! ��

 

[stolarek]

I have 2006 V6. At first really didn't believe this would solve my issue with my brake pedal slowly going down either on stop lights or just when braking... I risked and bought Toyota part. Disassembled master cyllinder, replace the part and it worked! Thank you so much for saving thousands of dollars!

 

[Runnin on E]

I looked through the stickys from y=mt+b and I did not see this under brakes. Can this please be added?

 

[AuSeeker]

I looked through the stickys from y=mt+b and I did not see this under brakes. Can this please be added?

To get his attention [MENTION=429038]y=mx+b[/MENTION]

 

[Runnin on E]

Ya, I sent a PM.

 

[y=mx+b]

I looked through the stickys from y=mt+b and I did not see this under brakes. Can this please be added?

To get his attention [MENTION=429038]y=mx+b[/MENTION]

Appreciate the tag! I'm not on here as often as I used to be, but happy to keep everything maintained. Got it added under the brakes section!

 

[Runnin on E]

Appreciate the tag! I'm not on here as often as I used to be, but happy to keep everything maintained. Got it added under the brakes section!

This right here is why I keep coming back to the forum.