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Discussion Starter · #1 ·
I have a 2002 VW Passat wagon. We have had an extremely cold winter here in New England (coldest January since 1898!). Anytime the temperature goes under 10 degrees overnight, my brakes do not work in the morning. When I put my foot on the brake pedal, it does not move and the car will not stop. It takes quite a while before I have full breaking capacity restored. Eventually, it gets back to normal (sometimes takes 45 minutes of driving). In addition, the last time this happened, before I got full braking back, my front brakes locked up and smoked like crazy. When I put my foot on the gas, they disengaged. I've taken the car in for service, left it with the dealer the night before so that it would be there, cold, in the morning, but the problem didn't occur because the temp didn't get cold enough. They couldn't find anything wrong. That's because the brakes work fine when the temp is above 10 degrees. Also, under the same temperature conditions, my automatic transmission will not shift beyond 2nd gear until the car is warmed up.
Anyone else out there have this problem? Thoughts, solutions? Thanks!
 

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Re: Brakes fail in very cold weather (pmarhi)

I would flush the brake fluid out.
If moisture gets into the fluid, it could freeze and cause problems.
Brake fluid is hydroscopic, that is, it attracts moisture.
The trans is set to shift at higher rpms in the cold, to help
the cats warm up faster, but it should shift, just higher.
I would guess the fluid is a bit low, and when it gets cold,
it contracts, maybe lowering the level enough to cause problems.
VW says the fluid has to be at 98F when checking the level...
That, or you have a lot of moisture in things, maybe from lots of short
trips where things dont get hot enough to get rid of it.
odd problems...
Brett
2003 GLX
 

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Re: Brakes fail in very cold weather (pmarhi)

It's been colder than that here at various times through January and I have had neither problem. My car is not garaged.
I haven't heard of either problem, but I'd go with Brett's recommendation on that brake flush. No ideas about the tip tranny issue. Sorry.
Wait - I just re-read your thread...if they don't work, how are you able to drive for 45 minutes?


Modified by Altair 4 at 1:39 PM 2-17-2004
 

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Discussion Starter · #4 ·
Re: Brakes fail in very cold weather (Altair 4)

Very carefully!!! Initially, they do not work at all and the brake pedal does not move. But with each touch on the pedal, they get better, although, as I say, certainly not enough to stop the car under normal conditions. I make sure I drive very slowly and give myself enough room to stop.
I actually posted this problem on another forum (Car Talk) and got the same suggestion: Flush the brake fluid.
"VW requires the brake fluid be changed every 2 years as it can absorb moisture. This is probably the problem here."
My understanding from the Car Talk forum is that the brake fluid in a Passat is DOT 4 and is silcone based and therefore dose not absorb water, as normal (DOT 3) brake fluid does. I have called the dealer and asked him to flush the system. I'll let you know how I make out (May take awhile....must wait until it gets down to 5 degrees again).
Thanks for the help and suggestions.
 

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Re: Brakes fail in very cold weather (pmarhi)

Dot 5 brake fluid is silicone, dot 4 is regular brake fluid.
You cant use dot 5 in cars with abs, its too thick.
They used to use dot 5 on motorcycles, as brake fluid eats paint,
and the holly davis guys liked paint on their gas tanks.
I used dot 5 in a car without abs, and it worked great for many years.
They need to make a good silicone brake fluid for abs cars!
To get the crap out, you can suck most out with a turkey baster
type thing (watch the paint!), top up with new fluid, then bleed the brakes starting with the right rear wheel, then left rear, right front,
and left front.
manual cars use brake fluid for the clutch also, comes out of the same
place...i think...
Brett
2003 GLX
 

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Discussion Starter · #6 ·
Re: Brakes fail in very cold weather (pmarhi)

Another suggestion from the Car Talk forum. Make any sense?

"Another is the brake booster, moisture freezing in the booster preventing it from assisting on brake applications or preventing the brakes from releasing."
 

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Re: Brakes fail in very cold weather (pmarhi)

Its possible, but if the brake booster was the problem, you would
have brakes, but no pwer assist i think.
I think the VW uses engine vacuum to boost the brakes, some
cars use a hydrolic pump, but vacuum allows air and moisture
into things, so its possible.
Its quite unusual to have such problems unless things are very
moist and very cold.
Sure you just dont have brake boost?
The brake pedal will move, but it would be real hard to stop
the car...
Brett
2003 GLX
 

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Discussion Starter · #8 ·
Re: Brakes fail in very cold weather (Brett1)

Initially, the brake pedal does not move at all. And it takes quite a while for the pedal to move the normal distance. So it doesn't sound like the brake booster.
I am quite perplexed with the dealer on this one. Telling me that he couldn't find anything is one thing, but being ready to let me go out the door with a safety problem like this without recommending at least a flush seems unacceptable. I'm not big on dealers, but I've continued to take it there because it is still under warranty. I also have a 2000 Passat and would prefer to bring it to an independent.
Anyone know a good VW mechanic in the Lexington, Mass. area?
 

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Discussion Starter · #9 ·
Re: Brakes fail in very cold weather (Brett1)

I asked the dealer about changing the automatic transmission fluid. He tells me that it's a sealed system. Can you check the transmission fluid level? If you can, can it then be considered a "sealed" system? And if it is low, can you add more fluid? ( I think I can answer that one).
 

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Re: Brakes fail in very cold weather (pmarhi)

Quote, originally posted by pmarhi »
I am quite perplexed with the dealer on this one.

It is perplexing indeed. One other wild guess: perhaps there is a lot of morning dew in your area, enough that ice is forming around the pads and ofther parts of the braking system. Perhaps water from nearby sprinklers (I guess not n the winter
) are wetting your brakes. I would just look for a possible source of water that turns into solid ice overnight.
 

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Discussion Starter · #11 ·
Re: Brakes fail in very cold weather (av_audi)

No to the moisture, dew or water. If anything, It has been quite dry here. And wouldn't all this water freeze if it were only, say, 20 degrees? Water in the brake line seems to be the most likely candidate. The fact that it is mixed in with the brake fluid would mean that it would freeze at a much lower temp, don't you think? Almost like anti-freeze. Adding water to the brake fluid would raise the temperature at which it would freeze.
 

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Re: Brakes fail in very cold weather (pmarhi)

Quote, originally posted by pmarhi »
I asked the dealer about changing the automatic transmission fluid. He tells me that it's a sealed system. Can you check the transmission fluid level? If you can, can it then be considered a "sealed" system? And if it is low, can you add more fluid? ( I think I can answer that one).

There is no dipstick on the tiptronic to check the fluid. So, yes, it's a sealed system. But fluid can be added - just ask the members who mistakenly removed the transmission drain plug when they wanted to remove the engine oil drain!

The transmission has to be in a certain temperature range in order to fill it. The dealer uses their diagnostic tools to measure the temp and then add the fluid. I think you need a special tool to add the fluid, too.
 

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Re: Brakes fail in very cold weather (pmarhi)

The trans has a drain and fill plug, you unscrew it to check the level
and add fluid, and yes, the trans is supposed to be at about 98F.
I dont wonder about the dealer, they are clueless.
perhaps mention legal action if anything bad happens, the lemmon law, or maybe you might loose the brakes on his lot, smashing into
all those nice patheons...
Seems quite crazy to ignore complaints like you have, with all
the poor lawyers around...
Brett
2003 GLX
 

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Re: Brakes fail in very cold weather (pmarhi)

Quote, originally posted by pmarhi »
Water in the brake line seems to be the most likely candidate.

Yes, that's what I thought too at first along with everyone else. But what you describe seems very extreme. It implies that the fluid is frozen solid in the lines. How can that much water get into the system in the first place?
There is one thing you can try as a test. If the brake pedal feels frozen again in the morning, just keep pumping it (with engine on). That should heat up the brake fluid fairly quickly to melt any frozen water. See if that helps. It would also give you a clue about whether it is a frozen fluid problem.
 

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Re: Brakes fail in very cold weather (av_audi)

On brake systems, all you need is a small piece of ice to plug
a port up someplace.
The abs system has valves that need to operate, and they have
screens and small ports, as well as very close fit valves.
Many a Jaguar got a ruined ABS valve body from people pushing
dirty fluid back into the system when fitting new brake pads.
(dont ask me how I know this)
The Jaguar list was full of problems, all from very small amounts
of dirt/rust in the system, so ice could be a problem.
Brake fluid is hydroscopic, it absorbs moisture out of the air,
and its possible it could settle someplace and form ice.
In the summer, water boils and turns to steam, and you can loose
the brakes then.
All brake fluid says to only use it out of a new sealed container, and not save left over brake fluid.
That is on every bottle you buy, for a good reason...
Brett
2003 GLX
 

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You may want to check your vacuum hose for the brake booster. I just had mine replaced under warranty. The dealer said the cold led to its collapse!
Regarding the tranny shifting issue - my Passat is manual, but our other car is auto, and I've noticed the cold weather upshift behaviour you did. It is part of the engine warm up cycle. If you took the car out on route 128 cold, I'm sure you'd see an upshift, but probably not all the way to 5th until it warms up.
 

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Re: Brakes fail in very cold weather (pmarhi)

Hi. I have a 2002 Mercury Villager that is having identical braking problems during extreme cold temperatures. I'm curious what kind of repairs were necessary to resolve your frozen brake problems during cold weather.
 

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Re: (klevin)

Quote, originally posted by klevin »
You may want to check your vacuum hose for the brake booster. I just had mine replaced under warranty. The dealer said the cold led to its collapse!


Bingo... Got on this thread a little late. As for the suggestion of "lemon law" on a 6 year old car, it would never happen.
 

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Re: Brakes fail in very cold weather (vickib4108)

whoa someone looked in the graveyard for this.. 04.....
 
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