Hey guys -

I've recently noticed a noise coming from under the hood and traced it back to the part in the attached video. Forgive the noob questoin but I'm not even sure what I'm looking at. Any help with what's going on would be much appreciated! Btw, this is on an '08 GX with ~145k miles.

Thanks!

 

That's the brake accumulator part #47950-60020

I don't know why it's buzzing. Buzzing is usually related to ABS. I am not sure if the accumulator goes bad if you get buzzing. I am not good in this area as I have not had any brake issues.

 

The brake booster on the GX is driven by an electric motor and that's what's causing the accumulator to buzz.
If it fails, you suddenly have no brakes. DO NOT DELAY getting this fixed, and you probably shouldn't drive it until it is.
New ones are expensive ($900 + labor) but there are rebuilt ones available in the $300-400 range. Check with a Toyota dealer - I believe this part was also used on the 4Runner.

Chip H.

 

Wow, thanks, Chip! I had no idea (obviously). I will get after the repair ASAP. I found a guy through one of the 4Runner forums who rebuilds these types of things. Will update this thread as I learn more. In the meantime, the GX is going to sit idle in the driveway.

 

I recently had a similar problem with my 2009 GX470, and it turned out to be an easy, inexpensive fix. Even though you (ebradford) may have already solved this, I'll share for others who might have a similar problem and stumble on this thread.

I bought my used GX about a year ago and noticed that every nine seconds or so the headlights would dim for just a second (while driving at night). If I was parked and at idle, the RPM needle would bump up in time with the lights dimming - something was clearly putting a load on the alternator. I traced it to that very part, making that very noise. It was "cycling" like clockwork over and over again whenever the car was running and the brake pedal wasn't depressed. I have since learned that the silver canister that shakes and buzzes is the accumulator that feeds the brake booster.

I went to my local Toyota dealer to have it checked (nearest Lexus shop is 90 minutes away). They said they inspected the system and found nothing wrong with it. I couldn't believe that they thought that was normal. When they gave it back it was now cycling every three seconds! It never affecting brake power or response so I kept driving it. After a few weeks I began to get a squeaking noise in the cabin every time it cycled; my kids joked that it sounded like a sick mouse. Although I hadn't found anything really helpful online previously I went back to Google and stumbled on a YouTube video that described the problem - common to the GX, the FJ Cruisers, and the 4Runners that share these parts. Inside that canister is a small plunger on a spring. It gets dirty, worn, or whatever, and it binds up, affecting the flow of brake fluid through the system. That extra labor to move that plunger is what causes it to shudder. I have not doubt that if it isn't repaired it can indeed damage the brake system.

The simple fix is to unscrew the accumulator canister (after pumping the brakes a bunch of times to let the pressure off the system) and then either clean or replace the little plunger. It sits down in the hole in the tubing that the accumulator screws onto. It sticks up into the bottom of the accumulator canister. I chose to replace the plunger, the spring, and the little O-ring that seals the accumulator canister. All in I think it was $11 in parts from one of the online shops. It took just a few minutes to do it. I had a few drops of fluid come out the bottom of the accumulator, and when I was done I didn't bleed the system or get any indicator lights. What has happened is that the accumulator isn't cycling very often now. It cycled every 30 seconds or so right after I made the repair, but after a drive, I watched it for over a minute and it didn't cycle once. Apparently the system restored itself;and the flow of brake fluid. That repair seems to have done the trick.

I had read on numerous sites that Lexus/Toyota's response has been to replace the very expensive brake system parts, but this quick and inexpensive repair has fixed the problem for me. Or so it seems. The YouTube video has been around a while with a number of comments from folks who confirmed it worked for them, and it worked for me, so I'm sharing it here. You can find the video here: There is a parts list in the comments for the plunger, spring, and o-ring. It's worth giving it a shot if you're having this same problem, at least before dropping thousands of dollars on new components.

Good luck!