Brakes failing help

Hello. Hoping someone can confirm what research so far makes me think. Been doing the work myself but not sure on this issue.

Just had my brakes start having issues and think it's the booster or cylinder. Symptoms are
1)when on it makes an air letting out noise when pressing brake peddle every time. Brakes normally till toward the end when u have to almost stand on it.
2) when turned off u get a few brake presses before it is completely hard and can't be pressed

Minor squeak from rear when pressing brake in drive or park.(think unrelated since its done that for awhile)
Guess I can't upload videos. I'll add to YouTube in a few.

Any advice is appreciated. Novice here.

 

Sounds like the brake booster is done for. Here is a simple test to see if it is holding vacuum:

http://www.roadkillcustoms.com/hot-rods-rat-rods/hot-rod-power-brake-booster-test.asp#axzz4xBsYwKg4

 

Thank you. I was looking for something like that. I'll test tonight and get back. I'm hoping it isn't too painful to do myself. Just did all my joints which wasn't fun.

 

Brake booster isn't too hard to swap out. 4 bolts inside the cab, brake pedal linkage, 2 bolts to the MC and a vacuum line.

 

seems like i'm going to have to do this. my brakes started acting really squishy lately

 

Squishy is not usually a problem with the booster, that is more indicative of air in the system. Try replacing the fluid in the reservoir and bleeding all four corners until new fluid comes out with no bubbles. Check that all bleeders and brake line connections are tight.

 

All of that sounds normal to me. You obviously will lose hydraulic pressure when you press the brake while the truck is off and the booster isn’t doing anything.

The “air” noise is also normal.

The only thing not normal is you say it brakes fine at first but then you have to stand on it. There’s more than likely air in your lines if that’s the case. You need to bleed your brakes. This happens because the air compresses so you lose brake pressure as a result. If you keep getting air in your lines then your cylinder seal could be toast. That can happen when you let the brake fluid get too low and not topping it off properly while you are bleeding the brakes. In that case you will probably need to swap the cylinder.

 

It seems to pass the booster tests. I noticed a clicking when i brake that I can feel in the shifter area if I hold the plastic. Only when car is on it clicks every brake press.

Its possible I got air in my line. I changed joints in the last 100 miles and the lines were pretty old.

Also I had heard a pop which I thought was CV coming out. https://www.tacomaworld.com/threads...questions-cv-popped-out.514717/#post-16267853

 

Took two videos to hopefully help. Does this seem like air in the lines? Its obviously making an air noise but i thought it was the booster bellow.

https://youtu.be/jtBfc16_6zM
https://youtu.be/63ZDUOoFaBo

 

That's a funky noise. Doesn't sound normal to me. At least no that loud.

I would still check the line for air, starting with the furthest wheel away from the res and working back.

 

I don't know what would make that air noise other than the booster. Sounds like it's sucking air in and out through the push rod. It shouldn't do that.

The clicking by the shifter is just the shift lock mechanism that prevents taking it out of park without the brake on (if you have an auto trans).

 

Bleed your brakes again and let us know if that helped

 

I will be doing so this afternoon when i have another pair of hands to pump the peddle. I'm wondering if that behavior could be explained by a line tearing or popping off when i was doing the ball joints a short while ago. Guess ill find out when i bleed them.

Thanks for everyones input so far.

I may actually try this gatorade bottle + tubing + fluid trick I'm seeing to bleed it myself sooner.

 

Two person method is best.

I'm not sure the set up of the trick. If you have the hose from the bleeder into a glass of brake fluid, open the bleeder and pump the brake pedal, then air can still get sucked back into the system between the bleeder valve threads when you let off the pedal with the bleeder open.

 

That’s what I do, it works fine. Just make sure to keep your resi topped up and make sure the hose stays submerged in fluid

 

Issue resolved. Brake booster was culprit as suspected. Brake lines had no air in them and tested good.

Was able to push master cylinder out of the way enough to wiggle booster out and in without disconnecting lines. Just had to move a few wires and vacuum lines out of way. Second set of hands is a must if trying to do this. I just pushed down and back slowly on master cylinder and payed attention to the lines while second person wiggled booster out.

Guide i followed: was spot on except my cylinder had 4 nuts attaching to booster instead of the 2 the 4runner had.

Note for others who read:
1) check if you need vacuum caps at store. the new ones seem to come with a spot for 3 vacuum lines. My 1999 only had 1 on its OEM booster. Had to go back to get caps to cap off the other 2. Seems the aftermarket are for a few different cars hence the multiple lines. At least it has a lifetime warranty.

2) Multiple 3/8 extension lengths are essential due to angles under dash and near master cylinder, ~8in and ~12in. Swivel would be helpful but i couldnt find mine and did without.

3) taking plastic panel under wheel off does not give you any more room as I found. dont bother.

 

Thanks for following up!

 

nice work