Frozen Brake Lines?

[concretejungle]

Out here in Colorado it's been below 0 for a week straight and every time I start the engine, I'm very happy to find that it starts right away...it's the stopping that needs attention.

Symptoms: brake pedal won't depress, vehicle won't slow down

Other Notes: only happens in freezing temperatures, only happens when not sheltered from the weather for more than an hour, consistent problem (happens every time I start the engine), symptoms stop after a minute of engine running

Possible Diagnosis: frozen brake lines (didn't think it was common, or possible, or maybe I've just never heard of it happening)

Any input would be nice. This isn't an emergency, just need to know that if something isn't going to work exactly right, that it's not going to cost me too much time/money/effort.

Thanks

 

[GarageBuilt]

When was the last time you did a brake fluid flush? Brake fluid is hydroscopic meaning it is able to absorb water to prevent rust inside the brake lines. Old brake fluid will have a higher water content allowing it to freeze (solid state). A solid does not compress.

 

[t4r4life]

brake fluid absorbs water and the line can be clogged with ice. i would just warm up the truck then bleed the whole system.

 

[LittleCaesar]

If the check valve has not been replaced, start there. Don't forget the grommet. Usually this only occurs at start up, until the engine gets warm enough to feed warm air through the check valve into the booster. I did see it once in MN where the valve failed even on a hot engine (ball was somehow stuck).

If your brake fluid is a nice brown/black color, then possibly the brake lines are gone. Bleed the brakes and if the fluid is just nasty looking (I have even see green brake fluid), then spend $65 at Wheelers for some SS brake lines then bleed the system again.

Also see if the booster is failing. Any hissing? Turn off the 4runner, pump the pedal 5 times, and see if pressure is held. If so, then good to go.

 

[blonde1boarder]

Here is a link to a previous thread discussing the issue. Same thing happens to mine.

http://www.toyota-4runner.org/3rd-gen-t4rs/102376-vacuum-check-valve-brake-booster.html

 

[TheArkMaster]

Happened to me the other day. I went to back up and barely missed my mailbox trying to avoid a car cuz my brakes didn't activate. hasn't happened since.

 

[slapdappy]

exact same thing. caught me off guard the first morning. next morning i let it warm up longer, they unfroze within 30 seconds and a couple of gentle stops. same thing yesterday morning. I'm confident it is not a water-in-the-fluid issue because I flushed my system recently. I figure it is a 0 degree morning issue, not an indicator of a part failure. Same thing happened to my outback.

 

[concretejungle]

Well I guess I'll start with bleeding because I don't think it's ever been done to the 4R once. If it still happens it might be a broken/malfuntioning part. But I'll just hope it's a temperature problem that I just have to deal with. Thanks for the input everyone.

 

[mn_swede]

I had the same problem here in MN- followed the advice below and have had no problems since.

Quoted from Yotatech:

"Its a common problem in these trucks. It is the brake booster vacuum check valve. It builds condensation and the valve freezes closed when it gets old on a cold morning after sitting. You cant buy this from a parts store and the oem part is $40. What I did with mine last year was to remove the check valve and soak it in WD40 from both ends. The lube is hydrophilic so it will displace the water/ice inside as well as lubricate the valve. "

 

[Gerdo]

Brake check valve.

Simple to replace.
Been there, done that, fixed the problem for me.

 

[white_n_slow]

Haha, just posted this on Saturday.

http://www.toyota-4runner.org/3rd-gen-t4rs/156743-brake-failure-help-me-diagnose.html

 

[concretejungle]

I had the same problem here in MN- followed the advice below and have had no problems since.

Quoted from Yotatech:

"Its a common problem in these trucks. It is the brake booster vacuum check valve. It builds condensation and the valve freezes closed when it gets old on a cold morning after sitting. You cant buy this from a parts store and the oem part is $40. What I did with mine last year was to remove the check valve and soak it in WD40 from both ends. The lube is hydrophilic so it will displace the water/ice inside as well as lubricate the valve. "

Oh awesome. I'll try that for sure. Thanks.

 

[concretejungle]

Haha, just posted this on Saturday.

http://www.toyota-4runner.org/3rd-gen-t4rs/156743-brake-failure-help-me-diagnose.html

Haha sorry. I searched for something similar but didn't see anything. Glad I'm not the only one experiencing this though.