cold weather brake problem?

[kjoyes]

My problem is this i live in minnesota and i noticed when the weather drops below 0 or negive -10. I cold start my car it is like really hard to press in the break pedal. i have to use all my weight to get my car to stop. the best way to decribe this is it is like not having power steering but in the break pedal this is really dangerous because my car wants to go forward when i put it in drive.
But once my car warms up the problem goes away. also in cold weather my window tend to frost alot on the inside witch is annoying as well. runs fine in the summer!
resently changed radator fluid put redline antifreeze stuff in it.. changed the power stering fluid to amsoil sythetitic transmission fluid.
The troubleshooting would be either
1. break fluid freezing
2. break booster ? explan what a brake booster is please?
3. lines (my brake fluid is not leaking because level has not changed).
?

[Conn SVX]

A brake booster is what gives the power brakes power. In the old days there was a HUGE vacuum bell mounted on it hooked to the motor. Slight pressure on the pedal opened the valve and the Vacuum pulled on the master cylinder .
I believe you problem is thickening of the brake fluid or moisture on the caliper. Possibly using a better grease on the caliper slides might help too. IMHO of course

[Tapani]

This is strange issue, we have had the same problem with the (2007) Forester and the (2008) WRX. It starts usually when it goes below -18C....

Both cured by replacing the one way valve in the booster vacuum tube. The Subaru one is a sort of a "plug" pushed inside the tube..... I have just cut the tube, taken the "plug" out and replaced that with an inline valve from an auto parts store. Both cars have been problem free since. There's nothing obvious that's wrong with the original valves, though....

A few other people have reported the same thing on the Subaru forum over here.....

My (2006) Outback is ok, though the set up is identical. Haven't driven the SVX in cold weather (yet).

FOr the steamy windows - do not use recirc at all and you should be fine. Or maybe you have water on the floor?

Br,

Tapani
Finland

[92snowmachine]

subaru has technical service bulletins about this specific problem. they claim it's a bad master that allows water to enter the fluid in humid climates and freeze when very cold. have replaced a few masters for this problem and never had any come backs. they don't cover the older models but the symptom sounds the same.

[Huskymaniac]

Originally Posted by Tapani

This is strange issue, we have had the same problem with the (2007) Forester and the (2008) WRX. It starts usually when it goes below -18C....

Both cured by replacing the one way valve in the booster vacuum tube. The Subaru one is a sort of a "plug" pushed inside the tube..... I have just cut the tube, taken the "plug" out and replaced that with an inline valve from an auto parts store. Both cars have been problem free since. There's nothing obvious that's wrong with the original valves, though....

A few other people have reported the same thing on the Subaru forum over here.....

My (2006) Outback is ok, though the set up is identical. Haven't driven the SVX in cold weather (yet).

FOr the steamy windows - do not use recirc at all and you should be fine. Or maybe you have water on the floor?

Br,

Tapani
Finland

Do you have a picture of where this valve is and do you have a part number for the replacement?

Hopefully the valve is the problem and not the master cylinder.

[Tapani]

Sorry, no picture at hand...., but the valve is inside the rubber hose, which runs from the intake manifold to the brake booster. There's on spot where the hose feels a bit thicker - the valve is right there.

The replacements I used are just generic one way valves from an auto parts store. Nipple diameter 10mm, if I recall correctly. Most other cars have this valve attached to the booster itself - like a connector to which the hose is attached.

5 minute job to replace.

Please reply your experiences, this is a rather interesting problem ..... :-)

Tapani