Brake line freeze?

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MDarius

MDarius

I break stuff.
SILVER Star
10 Year 15 Year
Joined
Apr 10, 2006
Threads
177
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2,059
Location
Bountiful, UT
So on cold mornings...say 20 degrees or lower, when we start up the cruiser and back down the driveway the brakes are unresponsive. Pushing on the pedal with all my strength and weight (i'm 225 lbs and 6'4''.) the thing barely shows any signs of brake contact. Pump the pedal several times, still no reaction. Get rolling a little, pump the pedal, and finally they are normal.

Is this a symptom of water in the lines, frozen components, failing master or slave cylinder, I need to go to the gym....?

It would really suck to start backing out and discover there's a kid behind you or a car turns the corner right then. It's only happened a couple times, but that's too many.
 
I have the same issue when cold. I believe it is what's called the Brake Check Valve. It's a vacuum valve between the engine and the brake booster that holds vacuum in the booster after the engine stops (so you can still stop if your engine dies). The problem comes when it freezes shut and won't let vacuum get to the booster on cold days.

I had the same problem with my pickup. I replaced the valve and the problem went away. It was only around $20 IIRC and it's in the vacuum line on the firewall. I haven't looked for it yet on the LC so I'm not sure if its in the same spot.

HTH
 
It could also be frozen calipers. If the sliding bolts aren't lubed they can sieze.
 
I've noticed the same thing. It's done it 3 or 4 times, the first brake pedal push after its been parked for while when very cold out has no boost. The second pedal push is fine. I know my brake fluid is fresh. Is it worth cleaning the check valve?
 
I had the same issue a couple of years ago and it was the check valve, you can see it on the booster. The plastic valve inside freezes up, I assume it has something to do with age. Only happened at very cold temps.
check-valve.webp
 
I have the same problem at cold temps, I ASSumed it moisture in my fluid or brake lines. I may invest in a new check valve.
 
Thanks for the pic, that helps. Now we are going to have a bunch of guys changing their check valves as a PM item! Hmmm....may not be a bad idea.
 
CowboyUp said:
I will be the one tomorrow morning :D!
How I can check this valves:doh: :hillbilly: ?!

:cheers:
Click to expand...

I assume if your brakes work as usual even on a cold morning its working correctly.
 
lndcruz said:
I assume if your brakes work as usual even on a cold morning its working correctly.
Click to expand...

Knock in the wood, all is fine! But after all this problem with the brakes when is cold, I started to get paranoiac. I all ready I am not using anymore the hand break after I learned that rear brake can freeze if the hand brake is applied.
:cheers:
 
CowboyUp said:
I will be the one tomorrow morning :D!
How I can check this valves:doh: :hillbilly: ?!

:cheers:
Click to expand...

My understanding of how this valve works is that it allows vacuum to be applied to the booster, but doesn't allow it to excape. You could probably test it by putting it in the freezer and then applying vacuum with a pump to the engine side of the valve. If the air is pulled through the valve- it works; if not- it doesn't.

Maybe someone with more knowledge on vacuum valves will chime in.

The only time mine hasn't worked is when sitting overnight in <10*F
 
People shouldn't be getting paraniod about this. Most mornings at my house it is anywhere from 10F to -20F so I deal with this on a regular baisis. I just press on my brake pedal 3-4 times as my truck is warming up and the brakes start working OK. I still plan on changing my valve out sometime soon. I will post up the results when I change out the valve.
 
Old brake fluid can do this too - the water starts falling out of it and turning to ice in the lines. When was the last time the brake fluid was changed on this truck?
 
it's not an expensive part - if you're going to take the time to pull it and test it, you might as well put in a new one. It was $42.40 at the dealer in 2008.

part number is 44730-28010

IMHO there is no reason to swap it as PM unless you experience the symptoms the OP describes.
 
My brake fluid was totally replaced 2 years ago. I'll see if pumping makes a difference. In the past it has always surprised us and I pumped it while the rig was rolling. I'm not sure if the vacuum from the engine is what is setting it free or if it's the pressure building in the brake line. Should be able to tell if it's the vacuum by checking the brakes when I start the engine. If they are stiff I can pump the pedal several times and see if it changes. If it doesn't then driving down the street a little should get the vacuum going, causing the valve to release. Sound realistic and correct?
 
So, you know your thread is dead when you reply to yourself, but I figured I'd close it out. Happened again over the holidays. I pumped the brakes and nothing improved. After running for maybe 45 seconds to a minute the brakes just magically started working. I'm sure it's this valve. Sounds like the vacuum had to build up in the system sufficiently to make it kick in.

Thanks for helping me isolate the issue. :Cheers:
 
It is more than likely the moisture that freezes in the 'check valve', as mentioned the valve gets a little damp and freezes when it is very cold. I have seen this happen to new valves as well, most wrap the vacuum line with some sponge and zip ties and there is no more problems. FWIW it seems to be more of a problem on vehicles used on short journeys perhaps because the engine is not warm enough to evaporate the moisture.

regards

Dave
 
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