Booster Pump / Accumulator Noise diagnosis (2 Viewers)

[Scottb4857]

Hey All,

Trying to diagnose which component or if it is both making this awful racket whenever I hit the brakes. Brakes do not feel spongy and with the new pads/rotors on all 4 corners when you stomp down it really stops well and no pulling to one side. ABS also working just fine - tested on some dirt last night.

Quick synopsis - it sounds to me that the system is pressurizing and at the end of each pressure cycle (every time I hit the brake pedal) it makes this awful noise. What I don't know is if it is the accumulator making the noise under pressure or the booster pump as it hits the higher pressures.

The noise is on the files - one inside the cab and the other in the engine bay with the engine not running. The sound of the booster pump is not really that loud - the audio file is deceiving and makes it sound like some huge racket - more of a slight buzz than anything. But don't have the volume too loud if you play - sounds pretty obnoxious.

http://d.pr/a/1iGQs
http://d.pr/a/1kR4T

Hopefully someone else recognizes this and can point me in the right direction. I'm hoping it is just the accumulator as that looks pretty easy to swap out. If the booster pump I'll be pulling the whole MC assembly and will just do the MC rebuild while I'm in there anyway.

Thanks all!

 

[uHu]

And I thought mine was sqealing...
Pretty nasty sound there, at the end of each pumping sequence. Haven't heard it before. Could it be an over-pressure valve opening? Or is it just the motor squealing when the load goes up?
Sorry - not much help...
How many miles? The booster motor will wear out somewhere well after 200 k miles normally.

 

[Scottb4857]

Truck is just shy of 238k. That's my question and trying to figure out. Sometimes sounds like the pump is still going with the same level of noise when the squeal starts but hard to tell over that squeal.

 

[TXLX100]

I'd start with replacing the fluid and see if that helps. Sounds pretty bad.

 

[Scottb4857]

I'll give that a try over the weekend. Fluid doesn't look bad, but there could be some contamination in there and brake fluid is cheap.

 

[TXLX100]

I'll give that a try over the weekend. Fluid doesn't look bad, but there could be some contamination in there and brake fluid is cheap.

Sure seems like a great candidate for Toyota/Lexus to do a recall since it involves brakes. I'm getting ready to rebuild my master cylinder because of soft pedal on first pump (which is also a safety issue if you don't really get on the brakes). I guess these things break, the HECU went out in my ford, but found a brand new part for $250.

 

[Keowee]

My truck had the same squealing sound last winter. Cold weather made it worse for some reason. It has had the soft pedal on first pump for a long while but the brakes are fine for now. I pumped the brakes with the engine off to release the boost pressure several times and the squealing stopped. Not sure if that was just coincidence.

Seems to be a common problem for the '99 year model and it should be a recall. Not sure how to get results on that. The only sure fix I've heard of is to replace the complete mc with pump and accumulator.

Anybody got a contact number for Mr Toyota? If we can get enough folks here on this forum to back a claim who knows.

A $2200. master cylinder puts me in a bad mood. Just a little discount would help.

 

[TXLX100]

Cruiser parts has some used ones for sale. But of course you could be in the same situation later.

http://shop.cruiserparts.net/index.php?main_page=index&cPath=7_109

 

[Keowee]

^^^Yeah, thought about a used one and with my luck it would just double my labor.

 

[TTO5]

I got a similar noise with my 2000. It's done it since I've owned it. I got it at 163,000 and now have 245k on it. Works fine and noise hasn't changed at all in the 5 years I've owned it

 

[Scottb4857]

Replaced all the brake fluid, drove it around on some dirt to activate the abs a few times, took it home and flushed some more - the poor mans version of using the SST. Brakes are even more solid than they were before, but didn't do anything to help the noise. After careful listening a bit more it really sounds like the pump motor continues with the same sound when the squeal starts. Guess next step is to replace the accumulator. Also think I will go ahead and rebuild the master cylinder while I have it taken out.

 

[SupraTuRD]

My '02 did the same thing. We determined that the pump motor bearings were shot, and the only way to repair it was to fork out $2k for a new master/booster assy. I know it's expensive, but I wouldn't want to lose my brakes either.

 

[ranma21]

My truck had the same squealing sound last winter. Cold weather made it worse for some reason. It has had the soft pedal on first pump for a long while but the brakes are fine for now. I pumped the brakes with the engine off to release the boost pressure several times and the squealing stopped. Not sure if that was just coincidence.

Seems to be a common problem for the '99 year model and it should be a recall. Not sure how to get results on that. The only sure fix I've heard of is to replace the complete mc with pump and accumulator.

Anybody got a contact number for Mr Toyota? If we can get enough folks here on this forum to back a claim who knows.

A $2200. master cylinder puts me in a bad mood. Just a little discount would help.

Can hook you up for one with great discount,PM me if you like one.

 

[Scottb4857]

Noise is gone - was the booster pump. I really didn't want to drop $2k on a whole new assembly so rolled the dice and found a used pump/accumulator from a semi-local parts yard. What made the search much easier for this part is the 2000-2002 4Runner used the exact same pump/accumulator (only this part, MC and ABS unit is different). Finding this out opened up a whole bunch of new possibilities on parts and donor vehicle was an 02 4Runner with only 70k on the clock before it met an untimely end. Put it all backed together - followed the FSM directions for bleeding the pump and all four corners. Stops like a champ and is completely quiet - I'm definitely a much happier camper not having to hear that awful noise every time I hit the brakes.

 

[Octavious]

Old thread revival!!!

Mine sounds awful anyone have part numbers for the booster pump for a 02 100 series or the 4Runner cross over part?

 

[Rolocado]

47950-60010

 

[OverlandOutdoors]

Noise is gone - was the booster pump. I really didn't want to drop $2k on a whole new assembly so rolled the dice and found a used pump/accumulator from a semi-local parts yard. What made the search much easier for this part is the 2000-2002 4Runner used the exact same pump/accumulator (only this part, MC and ABS unit is different). Finding this out opened up a whole bunch of new possibilities on parts and donor vehicle was an 02 4Runner with only 70k on the clock before it met an untimely end. Put it all backed together - followed the FSM directions for bleeding the pump and all four corners. Stops like a champ and is completely quiet - I'm definitely a much happier camper not having to hear that awful noise every time I hit the brakes.

So I bought a rebuilt booster pump and had my local mechanic replace it. He did this without having to take everything else apart so it was a quick fix. I read though that you and some others bleed the brake system and follow some other instructions that maybe my mechanic didn't do? I ask only because I still have the same loud grinding noise. Usually only upon first starting my 00 LC after it has sat overnight. Any ideas?

 

[Rolocado]

So I bought a rebuilt booster pump and had my local mechanic replace it. He did this without having to take everything else apart so it was a quick fix. I read though that you and some others bleed the brake system and follow some other instructions that maybe my mechanic didn't do? I ask only because I still have the same loud grinding noise. Usually only upon first starting my 00 LC after it has sat overnight. Any ideas?

If you’re able to in addition, ask your mechanic how he did it with the MC still in

 

[OverlandOutdoors]

If you’re able to in addition, ask your mechanic how he did it with the MC still in

He had told me that no brake fluid flows through actual booster pump.

 

[uHu]

He had told me that no brake fluid flows through actual booster pump.

If that was supposed to read "through the actual booster pump MOTOR" - it would be right.
It is the motor that wears first, it looks like, and it is possible to change without taking everything apart. If that motor was fully serviced (bearings, commutator, brushes), then it must be something else making noise, like the pump itself.

Btw, you will hear the booster running whenever you turn on the ignition after leaving it for a few hrs. That's normal. The question is if you have an abnormal grinding noise.