Brake Booster or Valve 2000 4runner

[ultimatt]

having an issue with an intermittent brick pedal. When it happens you can press and release the pedal 1 or 2 times and it will return to normal. Usually happens right after the truck is started and put into gear and will randomly happen during operation.

Going to check it this morning, look for any vacuum leaks and remove / check the valve.

What have other people experienced in this situation? Likely the valve or the booster?

I have no brake or abs lights on indicating errors.

Thanks.

 

[BamaDrewski]

having an issue with an intermittent brick pedal. When it happens you can press and release the pedal 1 or 2 times and it will return to normal. Usually happens right after the truck is started and put into gear and will randomly happen during operation.

Going to check it this morning, look for any vacuum leaks and remove / check the valve.

What have other people experienced in this situation? Likely the valve or the booster?

I have no brake or abs lights on indicating errors.

Thanks.

I just went through the same thing about two weeks ago. I went through everything (brake bleed, master cylinder, valve in booster) only to discover that the brake booster was shot. I pulled a booster off a rig at PullAPart and it was bad as well. Forked over the $$$ for a new Cardone brake booster and everything works like a champ. The brake booster set me back $225+$50 core charge from CarID.

 

[ultimatt]

Weird...I would have thought that a bad booster would go bad and stay bad...not be intermittent.

 

[thecole1098]

I would start with the cheapest option and try to replace the one way check valve first. Typically those will appear to be bad only in the morning when the engine bay/environment is the coldest.

 

[BamaDrewski]

Weird...I would have thought that a bad booster would go bad and stay bad...not be intermittent.

My brakes were behaving strangely on an intermittent basis before they finally died. I guess I was in denial about forking out the cash for a new brake booster so I went through everything before I determined it was the booster.

The vacuum valve can be easily checked. It is designed to let air through one way only (i.e. vacuum from the manifold) If you can blow air through the valve into the brake booster, the valve is bad. If it will not allow you to blow air in (in towards the booster) it is working.

 

[ultimatt]

New brake booster solved the issue. After the core return price was about $185 from Rockauto.com

 

[Pauleyman]

Looks like I'm having the same problems. I have narrowed it down the booster itself. I've tested the valve as I own a mityvac pump. Sometimes the booster will hold vacuum and sometimes it won't. The system is closed since I'm pulling with the tool and not the engine. No other place for vaccuum to escape except the booster itself.

 

[ambush]

Brakes

Looks like I'm having the same problems. I have narrowed it down the booster itself. I've tested the valve as I own a mityvac pump. Sometimes the booster will hold vacuum and sometimes it won't. The system is closed since I'm pulling with the tool and not the engine. No other place for vaccuum to escape except the booster itself.

I literally just went through a CRAZY time with this.
1st thing I would check first is the GASKET behind the master cylinder goes right in front the Booster. It is a PAPER gasket there. When you buy a new one, the manuals do not show that it needs one. I went to a few salvage yards to just get an idea what could be wrong, welp I saw a few paper gaskets that were very thin but had the shape of the MC. So I went to Oreillys and bought gasket maker kit and made my own. Guess what, I have brakes now (This is after also changing the booster 2xs and MC 2xs which did not solve the problems).

Take a look at that.

--Ambush