The specifics, 97 OBW 2.2 with 180K. Here is my problem and it happens when it is REALLY cold outside (32 and below). The brake pedal at startup is very stiff, and will not stop the car. That goes on for 3-4 seconds then goes away never to return. If I let the car warm up for a few minutes then drive I have no issues. What I did::: The fluid was bad off, looked like used motor oil. I flushed the system, I used the motive pump I just purchased what a great job. That helped somewhat, now it has to be 20 degrees for it to happen. Am I loosing boost? Could I have a leak in the booster? Seems like its not charging at startup?. Generally the pedal is somewhat stiff but at start up it does not budge. I did a engine swap recently and I do not know if I had the problem before as I never drove the car with the 2.5 in it. I have another sub I did the sam swap on with no issues. Any thoughts. There is a 99 Forester at the local bone yard so parts will be cheap if I need them.

I am almost positive there was a recall of the master cylinder for this very symptom. At least there was on my 98 GT.

 

Campaign Number: 99V040000 Date: 1999-Mar-03

Component: Service Brakes, Hydraulic: Foundation Components: Master Cylinder Defect Summary: VEHICLE DESCRIPTION: PASSENGER AND SPORT UTILITY VEHICLES EQUIPPED WITH ANTI-LOCK BRAKING SYSTEM (ABS). (THE 1999 2.2 LITER LEGACY VEHICLES ARE EXCLUDED). IN EXTREMELY COLD WEATHER, THE BRAKE PEDAL GOES TO THE FLOOR AND THE VEHICLE STOPPING DISTANCE IS INCREASED. Consequence Summary: THIS CONDITION CAUSES THE VEHICLE STOPPING DISTANCE TO BE INCREASED, POSSIBLY RESULTING IN A CRASH. Corrective Summary: DEALERS WILL REPLACE THE BRAKE MASTER CYLINDER.

Sorry. Close but no cigar...

I called the dealer, my car is not effected. There was only one open recall and that was for a front spring adjustment.

This problem has been covered recently and

is normaly attributed to moisture in the

vacuum booster line.

 

IIRC, there is a check valve that freezes, preventing vacuum from

reaching the booster.

 

You can remove the line and spray a moisture displaceant

into it.

 

I'll see if I can find the post on it.

The check valve in the vaccuum line to the brake booster gets frozen shut. Remove the valve, spray wd-40 inside to evaporate the moisture. That ussually helps.

 

Don't let anyone tell you you need a master cylinder, not even the dealer. It is the Check valve. a $5 dollar part, and all it needs is a bit of WD-40.

 

I lived in wisconsin for 5 year so I had this problem first hand

try this post/thread

 

Hope it helps

 

http://www.ultimatesubaru.org/forum/showthread.php?t=83038&highlight=booster+freeze

Thats my problem to a T. Lovely, easy fix.

You're welcome

 

Hope it's an easy/cheap fix.

Woke up this morning and had the same problem. I took off the hose and sprayed some wd40 in there. Blew some compressed air in the hose and replaced. We'll see what happens tomorrow morning. Thanks all.

OMG, I sprayed some WD40 in the pipe until it ran through and then blew some air in it. WOW, my brakes are 100% better.

Yup WD40 worked for me as well!

so far so good for me as well. gotta love a cheap fix.

How to tell its cold out, Blu has no brakes as i back out of the driveway (well i stand on the pedal and its fine).

 

Next thaw I have to spray too.

 

 

nipper

Our 2005 Forester has a similar problem--when it is less than 20 deg F, you have to use an ungodly amount of force  on the brake pedal to activate the brakes until it warms up or the brakes have been used a few times, then they are normal.   I have had the local Subaru dealer look at it several times and even suggested to them that it was a check valve.  They replaced other brake parts and the problem continues. 

 

Does this model have a check valve that can be WD40'd or replaced?  Seems like something I should be able to do myself but I could also use a diagram showing where this is (assuming we have one!)

 

Many thanks!

 

Bud

I've had this problem on my '94 Legacy many times. It's been especially bad this year, but then, it's been especially cold around here the last couple months. On mine, the first couple of brake presses work fine. But that third or fourth press - that's when it acts up. And that is the worst time for it to do so. I have trained myself to press the brake about a dozen times before shifting out of park. When I get to that 3rd or so press I feel the pedal get hard, then I keep nancying the pedal along until I feel it release. Then it's fine after that, until it cools overnight and repeats the issue the next day. I sprayed some lube in there a couple years ago, I think it's time for a refresh.

Our 2005 Forester has a similar problem--when it is less than 20 deg F, you have to use an ungodly amount of force on the brake pedal to activate the brakes until it warms up or the brakes have been used a few times, then they are normal. I have had the local Subaru dealer look at it several times and even suggested to them that it was a check valve. They replaced other brake parts and the problem continues.

 

Does this model have a check valve that can be WD40'd or replaced? Seems like something I should be able to do myself but I could also use a diagram showing where this is (assuming we have one!)

 

Many thanks!

 

Bud

Yes, every car has one. It is in the middle of the brake booster vacuum hose which leads from the engine to the brake booster servo.

 

Open the hood and look at the large round (probably painted black) cylinder behind the brake fluid reservoir. It will have a metal nipple sticking out towards the engine with a large hose attached. (Approx. 5/8" diameter)

 

Loosen the clamps with a pair of pliers, remove the hose from the booster and engine. Be sure to note which end goes where, since it will not hold vacuum in the booster if you reinstall the hose backwards.

Spray wd40 linerally into either end, until it runs out the other side. Blow it out with compressed air if available.

Thanks for your excellent answer!  I'm hoping that will resolve this issue for us!

 

Bud

Yes, every car has one. It is in the middle of the brake booster vacuum hose which leads from the engine to the brake booster servo.

 

Open the hood and look at the large round (probably painted black) cylinder behind the brake fluid reservoir. It will have a metal nipple sticking out towards the engine with a large hose attached. (Approx. 5/8" diameter)

 

Loosen the clamps with a pair of pliers, remove the hose from the booster and engine. Be sure to note which end goes where, since it will not hold vacuum in the booster if you reinstall the hose backwards.

Spray wd40 linerally into either end, until it runs out the other side. Blow it out with compressed air if available.

 

Thanks for your excellent answer.  I'm crossing my fingers that this will fix this stubborn problem for us!  Bud

I've had this problem on my '94 Legacy many times. It's been especially bad this year, but then, it's been especially cold around here the last couple months. On mine, the first couple of brake presses work fine. But that third or fourth press - that's when it acts up. And that is the worst time for it to do so. I have trained myself to press the brake about a dozen times before shifting out of park. When I get to that 3rd or so press I feel the pedal get hard, then I keep nancying the pedal along until I feel it release. Then it's fine after that, until it cools overnight and repeats the issue the next day. I sprayed some lube in there a couple years ago, I think it's time for a refresh.

 

Sounds just like our Forester.  I'm going to pass along your advice to my son who has the car at college.  It matches what I have suggested to him.  Thanks so much!