MistaMota

Hello.
i have a interesting problem with my 97 4runner. we have had a couple cold days now. -30c without windchill. and i start and let the runner warm up, but always within the first couple km or so when i step of the brake it will rock hard and you cannot push it down and the brakes will not engage. after it happens the problem doesn't happen until the next time i drive it.
what gives? i've already changed the brake fluid.
Thanks

Stetson_md

-30c that's like -20f right? Might have ice built up some where in the system or on the brakes themselves I'm not from a cold climate though so im just guessing

MistaMota

yea stetson i think -20f is fairly close to -30c. I'm not too sure where this ice buildup would come from as the brake system is entirely contained, so no water will get into it

DRCOFFEE

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. Knock on wood, hasnt happened again since then.

CJM

Picture of said valve?

Stetson_md

Condensation, deep snow, water crossings,all can get water into a old brake system or well anything for that matter. When you replaced the fluid did you bleed everything that touches fluid?

TheDurk

Here you go. It is part number 44730-60060 labeled as 44730 on second diagram. Applies to '96 to '00 only.

CJM

Thanks!

MistaMota

thanks, i'll change out the part this week thanks!!!!!

yes i did bleed out the entire system

MistaMota

awesome. i got a new valve. and now problems since!! thanks for the help!!!