Brake booster noise??

About 2 weeks ago I noticed a strange humming and or ringing noise while braking. It seems to get louder when applying more pressure to the brakes.
I checked the new led light bar I installed about 3 weeks ago since I ran the wiring thru the firewall and under the dash near the pedals to see if it was an electrical issue. Wires are all good. Even unplugged the power for the led light from the battery and it still makes the noise.
Popped my hood and the noise got louder and seemed to be coming from around the firewall. Checked brake fluid which was full. Would air in the brake lines be the issue? I did bleed them about 4 wks ago. Pedals seem nice and responsive though.
I did notice the humming get REALLY loud when I got closer to the brake booster, put my ear against it and it seems like thats the issue. When I shut the truck off the humming remains for about 10 seconds then gets quieter and then stops. What would cause that? Time for a new booster??? Easy to install or should I have a shop do it? Could it be something else?

 

Time for a booster. The diaphragm has gone bad inside of it.

 

I have the same issue, i bought a new booster

 

Have you installed it yet?? Noise go away? Took it to a shop and they ran all the tests to see if the booster was bad and said it passed. But he did spray soap and water on the paper-like gasket between the master cylider and booster and the humming starting chirping if that makes sense. Almost like it has a leak and the water was kinda clogging the leak? They said start there first with the gasket.

 

It shouldn't leak there. No gasket is supposed to seal it. Booster has a bad seal around plunger rod.

 

Hi my friend, I just ordered the New Booster and just arrived today, and when I take it to the mechanic he tells me that he check it well and was just the Master Cylinder, so I go to the store and they had one on stock, so I bought it and the mechanic is now intalling, i will go tomorrow to see how is working, but It was better because i return the booster to the shop (200 dollars) and just take the cylinder (55 dollars)

Did you replace both Master Cylinder and Booster?

 

I've never known a master cylinder to seal a booster or make hissing noise. New one on me if it does.

 

I havent replaced neither yet. I think I'm going to start with the gasket since its the cheapest route. Turns out my brakes werent bled properly to get all the air out so I wonder if pressure built up and blew the gasket hence the humming noise??

 

nope

 

What is the diagram from? Haynes manual? I've tried looking for one like that online of a tacoma and had no luck. I need to invest in a Haynes manual sooner than later just to have one for the truck.

 

Nah man. It's the Factory Service Manual from Toyota in electronic form. I've never been very impressed with the Haynes/Chilton stuff. But the Toyota FSM is truly priceless.

 

Also, I echo Jon's comments about the gasket as well as that other guy's fix being the cylinder. Unless he had different symptoms. Humming and noise will be from the failing booster.

 

Ok so I went out to my truck and you can clearly see a "paper like" gasket. Its the paper-looking tan thing lol. Very thin. Is this not a gasket of some sort or is it something else? I know in the diagram it doesnt show it. Just very confused and want the issue fixed but dont want to spend a small fortune if I dont have too.

 

Huh, apparently there is one. Seeing your pic made me do a little 'researching'(online reading, lol) and some have fixed certain brake issues with other Yotas by replacing this gasket. Interesting, here's a link I found talking about a bit. I'm not sure how a faulty gasket there can cause brake issues. It's just an empty void between the master and the booster. Wait a sec, does that 'void' share vacuum with the vacuum created in the booster??? No way, right?

 

Not that I know of. That would put direct vacuum on the back of the master cylinder piston.

 

Did you go thru the test procedures in the pdf I uploaded?

 

My brakes work fine. I'll loosen my master cylinder and see what happens. I'm curious now.

 

I tried that test yesterday. A friend told me how to do it. The pedal is still squishy after the test. I'm guessing theres still air in the system after I bled the brakes? *1st time trying to bleed them. Thought I got all the air out since the fluid seemed to be running steadily. Should I have done the front too? I got an extended brake line to go along with my lift so thought the rear just needed bled.

 

Its the power brake assist that is of concern right now. Can't hurt to do both.

 

My truck is doing the exact same thing..