I feel like this has happened in the past but more when it was -20F and colder.

Symptoms: overnight temps close to -10F/-25C
First several braking actions are extremely stiff, like there is no brake boost.
On the 3rd or 4th try the pedal sinks and all is normal after that.
Doesn't happen when it's warmer outside temps.

This Nissan Altima post (and Pathfinder and Xterra post after) has the same issue, and they mention that some Nissans might have had a faulty check valve hose (possibly deserving of a recall tbh), but no part number is mentioned.

Altima: http://www.nissanclub.com/forums/200...-new-post.html

http://www.nissanforums.com/pathfind...d-weather.html

http://www.clubxterra.org/forums/showthread.php?t=25677

Has anyone heard of this part being faulty for 4th gen Maximas?

 

Parts tend to shrink when they are cold, some more than others. This can create air leaks.

one of the hoses or fittings from the intake manifold to the power brake unit might be a bit loose. This might create an air leak.

you might want to test for this by spraying carb cleaner or some flameable substance at the connections. An unlit propane torch woukd work well too. If you hear engine speed increase, you have found your leak.

tighten any loose hose clamps .
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Great Tip! Thanks!

 

 

That's what she said ! LOL

 

 

I enjoy the humorous posts and comments on this forum.

 

The most probable cause is moisture in the brake fluid.

 

I agree with this more so than anything else. When's the last time you had a complete brake fluid power bleed where everything is pushed out and replaced? Most would say never! Added brake fluid after replacing _________, but a complete power bleed?

 

damn, some old heads chiming in this thread, thought you left us joe.

 

Yeah probably never, def have bled them each 'some' when changing pads/calipers. Sounds like a good idea anyway.

 

I've heard California is better

 

I'll replace the fluid. Odd that it never happens most of the time below freezing, until it's a LOT below freezing. -10f - 32f, no issues.

 

I respectfully disagree.

the original poster is talking about the lack of power brake function at sub zero temps.

No mention of the hydraulic portion of the brake not working. Sure, what you said about moisture in the fluid freezing makes sense, but that would disable the hydraulic portion, while the power brake portion would work fine.

So I will stick with my opinion that the hydraulic portion of the brakes are not the issue.

By all means, bleed the brakes. That' good maintenance anyway. Do not be surprised if the problem returns when sub zero temps return

 

Thankfully these very cold temps only occur about 25 nights a year on average (9 so far this winter). I've been finding that if I press the brake while in park about 5 times, then put it into drive, it tends to sink at that point and be fine, or requires a couple of more presses to be good. Over the weekend I'll check the hoses (I had many unhooked to replace a starter/knock sensor last weekend), and I will do basic tests of the brake boost.

 

You know, I'm not sure it would present too differently either way. Hard pedal whether from hydraulic fluid going real dense (ice crystals) or power brake booster leaking somewhere in the equation.

But what leaves me suspect is a vacuum leak or leaking power booster doesn't correct itself with a few pumps.

Whereas moisture out as far as the calipers just might.

I say we meet in Medicine Hat Canada (In the middle somewhere FREAKIN COLD), and do all kinds of scientific tests. Like drink Canadian Beer, Cuddle up (to stay warm of course) to beautiful Canadian women and so on!

We may never find the answer, but................

You know what I'm sayin?

 

KP, I'm sure that you remember the Rocky and Bullwinkle cartoons.

We could meet in Frostbite Falls, Minnesota.

Also known as International Falls, Minnesota.

Darn cold there too.

 

It's not the fluid ... It's the shrinkage of components, as has been suggested.

I don't experience any pedal feel or braking performance issues, but when temps (here in Florida) drop into the 50s, I get a hissing sound from the brake booster area (heard from inside the car) that disappears with the depressing of the brake pedal and upon the car warming up.

I'm not suggesting that regular brake fluid service isn't needed (it certainly is), but this symptom isn't fluid related.

... believe me ... if my brake fluid were a floor, you could eat off of it.

 

id bet one or more of the booster hoses is leaking. which brings me to .
since nissan has discontinued all the rubber booster hoses or for sure the one that goes to the valve cover has anyone found aftermarket hoses for these?. the OEM are molded. and would like to get similar if possible.

 

California taxes are wayyyyyyyyyyyyyyy too high!!!!! It is warm here though.

 

Haha, why Medicine Hat of all places...