Brake pedal hard to push down

[19963.4lsr5]

Having brakes for 2-3 tries with the engine of doesn't really mean anything with regards to if the check valve is or isn't working. It just proves the check valve is sealing in the shut position. It can still be stuck shut on occasion and prevent vacuum from getting inside the brake booster and cause a hard pedal.


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[shoota]

Having brakes for 2-3 tries with the engine of doesn't really mean anything with regards to if the check valve is or isn't working. It just proves the check valve is sealing in the shut position. It can still be stuck shut on occasion and prevent vacuum from getting inside the brake booster and cause a hard pedal.


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That's kinda what I was thinking. And the odds of it working while the engine is off is pretty good because more often than not my brakes work fine.

 

[catrains]

your wording also confused the hell out of me.

so if he got all hard pedals with the engine off, thats a test confirming a bad check valve?

his brake pedal is normal most all the time that is what he said. then he said sometimes it is hard to push down on brake pedal and hard to stop .

so if he shuts down vehicle no engine vacuum and the check valve is open the pedal will be high and hard in a second because its leaking... that is why there is a check valve to hold vacuum in the booster .

if the booster had a leak it would depend on how big of a leak , the bigger the leak with engine running the brake pedal will get harder as the leak gets bigger over time.

using a vacuum gauge to test/check , this is not complicated but who here has one LOL... DRIVE AROUND WITH VAC GAUGE CONNECTED TO BOOSTER SEE IF THE VACUUM IS GOOD ALL THE TIME . then he will know no leaks or the check valve is open when he shuts the engine off.

most likely with what he said last time it is a mechanical type caliper binding issue when the brakes heat up..

 

[shoota]

most likely with what he said last time it is a mechanical type caliper binding issue when the brakes heat up..

Can you elaborate on this for a noob please?

 

[19963.4lsr5]

If the check valve would be stuck open he would have brakes with engine running and no reserve vacuum in the booster with engine off. He has a hard pedal with engine running. It could be the booster but doubt it because it holds a vacuum when he tested brakes with engine off.


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[catrains]

Can you elaborate on this for a noob please?

if the caliper pistons stick or the hose to them is blocked the brake pedal will be harder to push down and less braking. this usually happens after the brakes get hot.

 

[shoota]

if the caliper pistons stick or the hose to them is blocked the brake pedal will be harder to push down and less braking. this usually happens after the brakes get hot.

The last couple times this happened it was pretty much right after I got moving and the truck had been sitting. It doesn't seem like that would be enough time to heat up the brakes?

So I guess I should just start with the check valve? Is that the general consensus?

(sorta off topic: I need someone to tell me what gear oil to get for the rear please. There's too many options.)

 

[catrains]

The last couple times this happened it was pretty much right after I got moving and the truck had been sitting. It doesn't seem like that would be enough time to heat up the brakes?

So I guess I should just start with the check valve? Is that the general consensus?

(sorta off topic: I need someone to tell me what gear oil to get for the rear please. There's too many options.)

you should start with the vacuum gauge testing to see if there is a booster vacuum issue. this will check both check valve/booster/hoses/seals .

 

[6ER17]

After learning to drive in an old FJ-40, I still have an old habit of pumping my break pedal two times when I need to stop. This winter, pumping the pedal started to give me a stiff pedal, but poor braking. I replaced the check valve and grommet, and the problem is gone.

 

[shoota]

so your booster and the check valve is good.
since it can occur intermittently then possible it is a brake caliper/hose /pad as the brakes heat up.. check that all the brakes are evenly at the same temp.

hoses do collapse internally at this age . fluid gets blocked hard to stop .. binding calipers/pads also. the hottest one is most likely the bad one. if all are the same temp when it messes up possible the master cylinder is binding but never seen that.

his brake pedal is normal most all the time that is what he said. then he said sometimes it is hard to push down on brake pedal and hard to stop .

so if he shuts down vehicle no engine vacuum and the check valve is open the pedal will be high and hard in a second because its leaking... that is why there is a check valve to hold vacuum in the booster .

if the booster had a leak it would depend on how big of a leak , the bigger the leak with engine running the brake pedal will get harder as the leak gets bigger over time.

using a vacuum gauge to test/check , this is not complicated but who here has one LOL... DRIVE AROUND WITH VAC GAUGE CONNECTED TO BOOSTER SEE IF THE VACUUM IS GOOD ALL THE TIME . then he will know no leaks or the check valve is open when he shuts the engine off.

most likely with what he said last time it is a mechanical type caliper binding issue when the brakes heat up..

If the check valve would be stuck open he would have brakes with engine running and no reserve vacuum in the booster with engine off. He has a hard pedal with engine running. It could be the booster but doubt it because it holds a vacuum when he tested brakes with engine off.

Ok so this morning I installed the new check valve and grommet on a cold vehicle, pulled out of the driveway and....hard pedal. So it's not the check valve.
A spent a couple trips going around the neighborhood to try to reproduce it and I figured it out. If I feather the brake pedal ever so slowly about 1/4 of the way through the pedal stroke I can hear what sounds like a leak. When I got home I parked and with the engine running I pushed on the pedal with my hand so I could look under the dash and try to pinpoint where the leak sound was coming from. Best I can tell (sound changes a little when I push on it) is that it's coming from here:

https://postimage.org/

So gurus what's the next move? Thanks!

 

[catrains]

on old vehicles high miles lots of traffic driving the booster does wear out with your location of the leak it is the booster.

have it replaced soon.

 

[shoota]

on old vehicles high miles lots of traffic driving the booster does wear out with your location of the leak it is the booster.

have it replaced soon.

Thanks gonna do that today hopefully.

 

[shoota]

on old vehicles high miles lots of traffic driving the booster does wear out with your location of the leak it is the booster.

have it replaced soon.

I think the $25 booster from the Pick N Pull fixed it. Thanks for your help.

 

[Tbishop9]

Can someone please tell me where this check valve is on the booster?? I have looked for it, and I at least like to think of myself as mechanically inclined. I know I'm just missing it, but a picture would be sooooooo helpful!!

2002 4runner limited
Thanks!

 

[4Runnermex]

Can someone please tell me where this check valve is on the booster?? I have looked for it, and I at least like to think of myself as mechanically inclined. I know I'm just missing it, but a picture would be sooooooo helpful!!



2002 4runner limited

Thanks!

2002 has an all in one ABS, master cylinder in one unit. Don't think it has vacuum line running thru

96-00 same booster
01-02 all in one unit


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[Wakko]

I think i have the same issue, hard pedal.

Is it better to buy from a pick and pull place or get a new one from an auto parts store?

 

[SpidermanGeek]

I think i have the same issue, hard pedal.

Is it better to buy from a pick and pull place or get a new one from an auto parts store?

Do you get Brick Pedal only on cold mornings?

Could just be the Check Valve

 

[Wakko]

No, it was about 50 outside when this happen. Odd though because i don't recall any warning signs and it braked fine the day before. Started it up in the morning and it just went hard after 2/3 brakes and didn't feel like the brakes stopped.

To provide an update, ended up with a re-manufactured brake booster and it solved the issue. In retrospect, i think the signs were there slightly squishy brake pedal but it would stop. I guess it finally gave out because the brakes feel completely different now (non-squishy).

 

[Kananz808]

So this week this problem started and it's intermittent. It feels exactly like when you pump your brakes 4 or 5 times and it gets harder and harder to push the pedal down. Needless to say this a serious safety concern. Everyone I've talked to seems to think it's the master cylinder but from what I've read the mc just goes bad once and for all, not just kinda every once in while like mine. What do you guys think?

I’m having the same problems. Changed the break pads, bleed the breaks, was about to change the master cylinder but instead I went to a “break specialist” to diagnose the problem. He said it was the break booster. Changed the break booster (myself with help from my dad) and it worked great for about a week then went back to being stiff. Waisted $100 since the “specialist” was wrong! Had a friend, who is a certified mechanic, hear about what was happening and that changing the booster didn’t help. Now he is saying that it’s the hard lines from the master cylinder,they’re clogged and I need to change all of them . Another person told me the same thing but told me to “vacuum the lines don’t change them”. My 4Runner is 2000 v6. Just reached 200 thousand miles just changed all the belts. It’s a great car and I refuse to get rid of it! How do I fix this? How did you fix yours?

 

[3bears]

clogged lines and use a vacuum...….that's a new one for me
never heard of that but anything is possible I guess