Taos

If the outside temp gets below 10, my brakes are like a brick. As soon as the engine warms up some, the brakes work fine and the pedal softens back up. Sometimes this takes a minute, sometimes more. When the brakes are 'frozen' and the pedal hard (it will not go down), the truck will not stop when you press on the pedal.
I have had the brake fluid replaced.

DeathCougar

iTrader: (23)

Might have water in the booster. That can cause the same issue.

AP4CHE

I'm away for work right now and it got really cold down south where I live, my girlfriend tells me she's having the same problem this week.(I think, women are bad at explaining these things) I'd like to get some insight as to what it might be as well so I know what to look at when I go home.

AP4CHE

the truck stops but u have to press on the pedal so hard and so early to make sure ur going to stop
then it doesnt stop completely it still like inches forward
well it always works after a w hiel

there's her explanation, same thing as you im guessing.

SoCalPaul

Sounds like your booster is not working when it's cold. Probably a vacuum leak or a frozen valve.

http://auto.howstuffworks.com/auto-p...wer-brake1.htm

GSGALLANT

I had that same problem on my '93 4Runner. Replacing the check valve solved it for me (it was sticking closed when it was really cold out). As a test, you can remove the check valve for a few days (put in a straight coupling in its place.) If the problem goes away, a new check valve should solve it (might be able to clean the existing one instead. I didn't bother trying... a guy I new was parting out his second gen, and I just picked up his check valve.) Don't drive around too long without a check valve in place. It is there to provide a couple of power assisted brake applications in case your truck stalls out on the freeway.

That being said, it could also be a booster problem.

X-AWDriver

Mine does that for like the 20-30 seconds after it is started but before I actually go too far I drive slow and pump the brake til it acts normal and mine has always done this. The system just needs a few pumps to start operating properly when it's that cold out.

If it is taking longer then you might have another issue.

Squiddy

Same problem for me

mkgarrison5

is there a write up or pics to show where this item is??

GSGALLANT

No, but it's quite easy to find. This is how it was on my '93 4Runner V6, anyways. Start at your brake booster, follow the vacuum hose until you get to the next component (looks like a small metal cannister about an inch in diameter or so, mounted to the firewall. The vacuum hose from the brake booster will be connected to one end of it, and a vacuum hose from the engine will be connected to the other end of it). On a 3.4L, though, the check valve might be built into the booster itself, right where the vacuum hose connects on the booster... not sure. My 2002 4Runner has a hydraulic brake booster, so I can't check to confirm.

Yukon

Same problem here. Usually after the first good pump they came back, but yesterday it was like -8 And they didn't start working at all, though i was just moving it so it wasn't on more than 4 minutes. But I was in an icy parking lot so i tested, and the brakes will work, I got the ABS to kick in, and the car stopped fine, you just had to literally stand on it.

creeve4

Having the same problem with my 94 4runner. Do you have a picture of the "check valve" GSGALLANT? Is that the correct name for the part?

SoCalPaul

Here is some generic info about the booster & check valve.

http://auto.howstuffworks.com/auto-p...wer-brake1.htm

If the check valve freezes closed, the engine will not be able to pull a vacuum on the booster which means that you have fully manual brakes. You will be able to stop, but it will take some effort.

Paul

Taos

I called my dealer. Told the parts guy I needed a check valve for the brakes. He had it for me the next day. I replaced the gromit as well. Easy job. It was located on the firewall. It was minus 5 this morning and the problem was gone. Well worth the $50.

97ltd4x4

Thanks for the follow up on the Fix!
(wish we got more fix updates )

Didn't happen to get a part#?

Godzilla

Pretty sure these are the numbers. If Taos can confrim that would be great as i may need this as well

This is for the grommet
90480-24517
This for the check valve
44730-60060

GSGALLANT

Glad to hear that it worked for you.

GSGALLANT

I don't have a picture (and I don't have my '93 4Runner anymore to go take a picture). It's very easy to find on your '94 4Runner. Follow the vacuum hose that goes from your brake booster towards the passenger side along the firewall. The check valve is a small cylindrical component, bolted to the firewall, with a hose barb sticking out of each end. Like I mentioned above, the hose from the brake booster connects to it.

creeve4

Found it! Thanks for the help and information!

Gerdo

WOW. I thought I was the only one with this problem. I guess I need to get a check valve.