odd brake problem (2 Viewers)

[missouriman]

It is very cold here. When first starting out the brake peddle is very firm, but brakes are at 10 percent at best. The other day I kind of forgot and ended up standing on the brake peddle with both feet at the stop sign that is about 1/8th mile from the house.

If you pump, or step on them many times all of a sudden the brake peddle (releases) and the brakes are normal for the rest of the day... 8 hours or so.

not sure what is going on, I was pulling on the steering wheel during the stop sign scare.

I have redone the brakes, flushed the fluid, bled the lines and the anti lock thing. Even if it were ice in the lines I sure think that standing on it and pulling on the steering wheel would have moved it. I also think that ice would just effect one wheel or the front or rear.

the rest of the time they work fine.
thanks for your time.

 

[BILT4ME]

Sounds to me like you have a caliper hanging up either due to debris or wear. Could also be loose wheel bearings causing a binding issue that goes away as you roll, but sitting still it binds.

Check your caliper retaining bolts and your wheel bearings. When you say brakes are 10%, does that mean there is only about 10% of braking ability happening or that there is only about 10% of the pads left?

 

[artech]

I get the same thing on mine when it's cold, the first step on the brakes on a frosty cold morning is very stiff. After one good very hard press it goes away and stays away until the truck sits overnight in the freezing cold. Next morning, same thing. Has to be below 15F for my truck to do it, about the same teperature where the power steering pump makes that startup racket. Never happens above freezing. Does not appear to be a stuck caliper because even on ice none of the wheels are locking up on that first brake application. It's like something in the brake booster is frozen up, then releases and after that she brakes normally until she sits in the cold for a while. No idea what causes it, hopefully somebody here knows? Oil in the vaccum line maybe?

 

[missouriman]

new pads, new calipers in the rear, fronts were still good... same problem as the last post, only when it is really cold out. And yes when the power steering pump is up set with the cold.

 

[Options20002001]

new pads, new calipers in the rear, fronts were still good... same problem as the last post, only when it is really cold out. And yes when the power steering pump is up set with the cold.

What year is your truck? Could be a defective or soon to be defective check valve on the booster.

 

[missouriman]

it is a 94. I forgot to post that I replaced the master cylinder last summer. front and rear pads, rear calipers. I wanted to replace the booster but to many $$ at the time.

 

[DARKNESS]

What year is your truck? Could be a defective or soon to be defective check valve on the booster.

Yeah that's almost certainly the booster check valve. Cheap and easy fix. Get the grommet too. Happened to me last year. I replaced it and haven't had any problems since even in extremely cold weather. Part numbers for 97:

44730-28010 (valve)

90480-24015 (grommet)

Not sure if these are applicable to all years.

 

[missouriman]

Yeah that's almost certainly the booster check valve. Cheap and easy fix. Get the grommet too. Happened to me last year. I replaced it and haven't had any problems since even in extremely cold weather. Part numbers for 97:

44730-28010 (valve)

90480-24015 (grommet)

Not sure if these are applicable to all years.

COOL, where is it? What's it look like? I WANT... Those part numbers didn't bring up anything at the napa site

 

[mnwolftrack]

I've had the stiff peddle on several vehicles (though not the Cruiser yet). In my experience, it has seemed to be the small push rod from the brake pedal going through the firewall into the booster/master cylinder that seems to seize up in extreme cold weather. A small shot of JB80 or Fluid film seems to do the trick. I haven't had to do this in the 80 yet, but I'v normally been able to see the push rod from laying upside down and looking up in the dash (meaning I didn't have to disassemble anything).

 

[DARKNESS]

The check valve is the metal thing in this picture that connects to the vacuum hose. The grommet is the rubber part that seals the valve to the booster.

I'd order one from Toyota. Use CDan or Beno or one of the many toyota parts websites. I usually use toyotapartszone.com. Replacement is simple. I think there's a metal tab to secure it that requires removal of one master cylinder nut, or you can just bend it up. Pull the valve out, pull the grommet out, then push the new ones into place. Requires a decent amount of wiggling and force, but it's not too bad.

What happens is the check valve gets stuck closed sometimes when it gets really cold and old and sits. That keeps the booster from developing vacuum which gives you a hard pedal. Eventually, it warms up or gets jarred loose and everything functions fine.

 

[missouriman]

The check valve is the metal thing in this picture that connects to the vacuum hose. The grommet is the rubber part that seals the valve to the booster.

I'd order one from Toyota. Use CDan or Beno or one of the many toyota parts websites. I usually use toyotapartszone.com. Replacement is simple. I think there's a metal tab to secure it that requires removal of one master cylinder nut, or you can just bend it up. Pull the valve out, pull the grommet out, then push the new ones into place. Requires a decent amount of wiggling and force, but it's not too bad.

What happens is the check valve gets stuck closed sometimes when it gets really cold and old and sits. That keeps the booster from developing vacuum which gives you a hard pedal. Eventually, it warms up or gets jarred loose and everything functions fine.

View attachment 1014756

Thank you very much for the info and the photo!!!

 

[missouriman]

ordered the parts today from toyotapartszone. after trying for a few days to find them local.

 

[Brentbba]

Looks like this is the location of the valve on my '94 and the nut holding the metal piece in front of the valve/grommet needs removal to take the old one out?

 

[Malleus]

Yes:

FWIW, 44610-60791 has been superseded by 44610-60792 (brake booster ass'y). Most people are using the Aisin booster.

44730-14060 (check valve) appears to be discontinued. 90480-24517 has been superseded by 90480-24015 (grommet).

(According to McGeorge's online store)

 

[Brentbba]

Interesting. OGBeno confirmed that the check valve part number he posted in this thread does fit the 1994 Landcruiser despite all the Toyota online sellers computers saying it doesn't. Joey at Wits End sells the valve, grommet and hose as a package for the 80 with the same part numbers as OGBeno too