No brakes in the morning. It will definitely wake you up more than coffee.

[WyrTwister]

I think you are right . I also seem to remember such a part connected to the vacuum hose & plugging into a grommet built into the booster .

I did find this sensor on RockAuto.com , but have no idea if it is related to your problem ?

More Information for AIRTEX / WELLS 5S7870

Have you seen such a sensor ? If so , you might , VERY CAREFULLY , try unplugging the electrical connector & see what the results would be ? Be prepared to use the parking brake , if you try this .

Photos , please ?

God bless
Wyr

[jamesd]

Here are some pictures. Could the check valve be in the intake? Nahh couldn't be right..? This braking problem always appears after the car has sat there for a while. This time it was just 2 hours and happens as soon as you start the engine and roll and then try to brake. Never has it done that it while driving or normal operations thank God! From what I see the hose connects from the brake booster to the intake. Nothing else in either end of the hoses.

[jamesd]

I think you are right . I also seem to remember such a part connected to the vacuum hose & plugging into a grommet built into the booster .

I did find this sensor on RockAuto.com , but have no idea if it is related to your problem ?

More Information for AIRTEX / WELLS 5S7870

Have you seen such a sensor ? If so , you might , VERY CAREFULLY , try unplugging the electrical connector & see what the results would be ? Be prepared to use the parking brake , if you try this .

Photos , please ?

God bless
Wyr

It does have that sensor. That is the brake fluid level sensor. It connects to outside of the master cylinder under neath reservoir. I know this because I just learned about it last week lol.. It came inside the box with the master cylinder. On the bottom picture you can see the paint blistering on the booster just below the master cylinder bolt.

[WyrTwister]

In the first photo , is the device I have circled in red , part of the brake booster vacuum system ( with the zip tie on it ) ? I do not think so ?

In the second photo , the area circled in red appears to be where the vacuum hose attaches to the booster . Where does the other end of the hose attach ? Should be at the engine , at a vacuum source . Intake manifold ?

Also , as a shot in the dark , have you thought about replacing the rubber hose ? Should be fairly inexpensive ?

More Information for ACDELCO 1761332

God bless
Wyr

[WyrTwister]

It does have that sensor. That is the brake fluid level sensor. It connects to outside of the master cylinder under neath reservoir. I know this because I just learned about it last week lol.. It came inside the box with the master cylinder. On the bottom picture you can see the paint blistering on the booster just below the master cylinder bolt.

Well , if it is a brake fluid sensor , I doubt it has anything to do with the problem you are having now .

God bless
Wyr

[jamesd]

In the first photo , is the device I have circled in red , part of the brake booster vacuum system ( with the zip tie on it ) ? I do not think so ?

In the second photo , the area circled in red appears to be where the vacuum hose attaches to the booster . Where does the other end of the hose attach ? Should be at the engine , at a vacuum source . Intake manifold ?

Also , as a shot in the dark , have you thought about replacing the rubber hose ? Should be fairly inexpensive ?

More Information for ACDELCO 1761332

God bless
Wyr

In first picture it's not tied in directly to the brake booster. On the second picture the hose it tied it directly to the intake manifold. I have not replaced the hose but.. why not right? So I will do that. As far as checking it I had the engine running and I got a spray bottle with water in it and mist all the hoses and listening for a vacuum sound. I could not hear non at the brake booster hose or at the intake side. I sprayed the rest of the engine and I did find a vacuum leak at the PCV valve hose. Fixed it, resprayed and couldn't find any more vacuum leaks.

[xintersecty]

Here is an interesting possibility I wonder if you have water in the vacuum system and it is condensation after sitting. Just random thoughts.

[jamesd]

Here is an interesting possibility I wonder if you have water in the vacuum system and it is condensation after sitting. Just random thoughts.

That is true... It could be a possibility. I know for sure because I used a spray bottle with water in it to find the leak. But I was doing the spray thing looking for the answer for the same issue i'm battling now. I like your thinking tho..

[xintersecty]

Thanks and here is an other consideration we can use science! Put a vacuum gauge on your line to the brake boost, let it sit, start the engine, and then engage the brake. That should indicate a failure on the vacuum system. Once it warms up the leak could have closed up due to expansion.

[jamesd]

Thanks and here is an other consideration we can use science! Put a vacuum gauge on your line to the brake boost, let it sit, start the engine, and then engage the brake. That should indicate a failure on the vacuum system. Once it warms up the leak could have closed up due to expansion.

I will definitely try that. I also have a vacuum pump as well so I will give that a try as well. I checked with the GM techs who are checking my car and they said they cannot duplicate the problem. Basically they said they are puzzled by it. They day is still young tho..