505taco

97 runner. In the mornings when it's cold the brakes are having problems. The first stop out of the driveway is when I notice it. I hit the pedal and nothing. Truck barely slows. I push the pedal as hard as I can and it just barely stops. After about 5 little brake checks they are back in working order. What's the deal? My wife took it out the other day and freaked. She said it almost wouldn't stop at all. Front Pads are new and Drums are good in the rear. It's like the fluid is not getting there when it's cold. Then after a few pumps it comes back. Pedal doesn't go to the floor or anything. It feels good. Anyone have this problem or something similar? What should I do? Flush the system? Help...

98LimitedCustomized

I'm not a brake expert or anything, but it sounds like you need to have your brakes bled. This same type of problem comes up now and again on all vehicles.... do a test next chance you get, in a safe place of course: Slam them to the floor, let them up, and do it again. On the second time it should be better.
Possible culprits would be low fluid level, air in the lines, bad brake lines, or even bad fluid. Keep an eye on it though, brakes are pretty serious when you think about what they do. Hopefully we have somebody else who has dealt with the same problem chime in soon!

rimpainter.com

I would not advise testing the problem by letting the pedal go all the way to the floor (if it will let you). That is a sure-fire way to blow out the seals in the MC.

Sounds like the brake booster or something. Anybody have the FSM test procedure for the brake booster?

Who did the pads, and did the problem exist before the pads were installed?

User 051420

Mine does this too..Drive's me nuts. The pedal is REALLY hard, but won't stop.

dragon564

Don't play around with ?????brakes get them fixed right away you never know when so non driver behind the wheel of a shinny and new FORD EXP-DENT-ION will require you to stand on them brakes. I have had to hit my brakes so hard that it blew the seal in the MC...but i did get stopped, needed new brakes and shorts but I stopped, brakes are cheap compared to the cost of accidents......trouble shoot them and get them fixed.

MTL_4runner

That is almost assuredly the brake booster or a leak in the hose going to it.
Remember the brakes use engine vacuum to help you stop, otherwise you would get that condition.
I assume the truck does not pull to one side or another which might indicate a stuck caliper.

User 051420

You're probably right. I'm always catching myself doing a slow double pump when I come to a stoplight. No pull. Like Chrsitian asked...Does anybody have the FSM page for this?

Too bad the part is around $600.

payyourtoll

mine do this too, only the first stop I come to, and only when it's REALLY cold out. I just kind of expect it now

rimpainter.com

A brake booster is $600?!

User 051420

$552.23, actually. 1sttoyotaparts.com

rimpainter.com

Wowzers! That is definitely the kind of thing you want to be certain on! (defective)

MTL_4runner

It is just a giant diaphragm so it should be pretty easy to test:

From another source:

"If the booster is working correctly, it should have no noticable effect on the engine, but if it is leaking, it will cause big problems. Use the following procedure to check yours.

Things you need:

Vacuum guage
Cap for vacuum port on the intake manifold
Friend to work brake pedal
Pencil and paper
Procedure:

Hook up the vac guage. Start the engine. Note the reading. This is your "base" reading.

Stop the engine, disconnect the booster vacuum line and cap the port on the manifold. Start the engine, look at the guage. If this reading is substantally higher than the base, you have a leak in the system, probably in the lines leading to the booster.

Stop the engine, remove and test the one-way valve (should be able to blow into it one way but not the other). Air should only pass in the direction indicated by the arrow printed on the top of the valve (make sure to reinstall it in the correct direction).

Reconnect the one way valve and vacuum line to the manifold and start the engine. Watch the vac guage as a friend depresses the brake pedal. It should dip as the pedal is depressed and return to the base reading. If it drops slowly, but returns, you have a blockage/collapse in the vac line. If it falls and does not return, you have a torn diaphram in the booster. Especially indicative of a torn diaphram is a hissing when the pedal is depressed. "


Might also take a look at this:
http://www.tlca.org/trails/techxchg/.../brak9509.html

User 051420

Thanks Jamie. I've always assumed it was crappy pads that made the first stop not so quick. I'm running whatever pads and rotors the shady used car dealer put on after I bought the truck 40k miles ago. I'll change the pads first, then move on.

Ugh..Exhaust leak, possible bad brake booster..Yuck!

HaveBlue

My Camry had the same problem. The culprit is just old brake fluid and a little water in the lines. Flush your brake system and it'll be night and day difference.
You can pick up two 32oz bottles of Valvoline synthetic fluid from Checker/Pep Boys/Autozone etc for ~$8.50. Buy a 24" length of 1/8" ID hose and a clear container (mason jars work well). Attach the hose to one of the bleeder screws on the caliper, open the screw, and push the brake pedal 20 times. Top off the fluid and push the pedal 20 more times. Continue doing this until the fluid coming out of that caliper is clear. The close the screw and move the the next caliper, then the rear drums.

Did I leave anything out?

MTL_4runner

This was to fix a hard pedal?