Vacuum Switching Valve Question
07-26-2007, 04:54 AM
Post: #1
Vacuum Switching Valve Question
I am loosing brake pressure, and I am getting a CLicking sound when I press on the brakes. The sound is coming fromt he Vacuum Switching Valve located by the VAF Sensor.

Any Ideas why, and while I am at it, what does the Valve do exactly?
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07-27-2007, 01:30 AM
Post: #2
Vacuum Switching Valve Question
mzdafrk Wrote:I am loosing brake pressure, and I am getting a CLicking sound when I press on the brakes. The sound is coming fromt he Vacuum Switching Valve located by the VAF Sensor.

Any Ideas why, and while I am at it, what does the Valve do exactly?

That valve near the MAF sensor is the IDLE up VSV. When you activiate ANY electrical load (IE: brake lights) it will click on. This is completely normal. Ignore it.

The brake pressure loss is a problem.
Is it a soft/spongy pedal that is the problem?
Are you loosing fluid?
Does it drop towards to floor?

Andrew
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07-27-2007, 02:00 AM
Post: #3
Vacuum Switching Valve Question
thanks for the explanation.

It was just the master cylinder, replaced it this morning, and all is better, just took some time and bleed all the brakes really well, and I have better brakes than I ever had before.

It was weird, it didn't act like a blown master cylinder, but I was loosing brake fluid, so It had to be the master or a leak. But couldn't find fluid anywhere on or under the car. So went for the $25 shot in the dark and it worked, I was leaning more towards the Booster. At least it is fixed, and I can stop again.
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07-27-2007, 03:04 AM
Post: #4
Vacuum Switching Valve Question
mzdafrk Wrote:thanks for the explanation.

It was just the master cylinder, replaced it this morning, and all is better, just took some time and bleed all the brakes really well, and I have better brakes than I ever had before.

It was weird, it didn't act like a blown master cylinder, but I was loosing brake fluid, so It had to be the master or a leak. But couldn't find fluid anywhere on or under the car. So went for the $25 shot in the dark and it worked, I was leaning more towards the Booster. At least it is fixed, and I can stop again.

If it was loosing fluid you should have been able to find the leak. Or it was leaking out the rear of the M/C into the brake booster... was it wet there?

Andrew
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07-27-2007, 03:09 AM
Post: #5
Vacuum Switching Valve Question
I couldn't find the fluid anywhere., but I am assuming that it was leaking into the Booster, the floor board and firewall were not wet. That is why it had me so confused, but I think maybe I was over analyzing the situation...lol.
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07-27-2007, 07:46 AM
Post: #6
Vacuum Switching Valve Question
I had a simillar problem but with the clutch master cyldiner... replaced the master cylinder and it worked fine Thumbs up!
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07-27-2007, 07:49 PM
Post: #7
Vacuum Switching Valve Question
Yeah same here, when we replaced the Master, and did a very thorough Bleed job, I have brakes better than when I got the car. It is nice, And when I talked with my buddy he said that there was a little fluid in the master.
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