Brake Booster Check Valve Bad?

[mikesoops]

I have a weird issue where the brakes will pump regular and stiffen after each pump when the car is OFF (normal). Then when I turn the engine on the brake pedal just sinks to floor. Brakes will work still but I need to press it all the way down (not normal). I wont drive it in this condition even if the brakes work. I dont feel comfortable having to press it all the way down to the floor to brake.

My brake fluid and lines are good. I checked. Did not bleed or flush fluid and lines yet. because before I do ..

Ive done research and bad booster means that the brake will be stiffer as they say. Not softer or opposite as in my case. so .... can I conclude that this is a valve problem?? My brake booster valve is not acting normal when the car is turned on?

could it be brake pressure sensor? or abs module?



does this sound right to you guys? anyone with this particular experience before?


UPDATE: just noticed my oil level is extremely low. im thinking that this is effecting the brake booster vacuum pump (hence why its acting weird only when engine is on). so going to Walmart to cop some oil and top it off and check back on this. hopefully this fixes it. I have no oil leaks but engine eats up oil. Must have bad piston rings or something... anyway, will be back with an update soon.


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2006 e53 3.0i

[upallnight]

Originally Posted by mikesoops

I have a weird issue where the brakes will pump regular and stiffen after each pump when the car is OFF (normal). Then when I turn the engine on the brake pedal just sinks to floor. Brakes will work still but I need to press it all the way down (not normal). I wont drive it in this condition even if the brakes work. I dont feel comfortable having to press it all the way down to the floor to brake.

My brake fluid and lines are good. I checked. Did not bleed or flush fluid and lines yet. because before I do ..

Ive done research and bad booster means that the brake will be stiffer as they say. Not softer or opposite as in my case. so .... can I conclude that this is a valve problem?? My brake booster valve is not acting normal when the car is turned on?

could it be brake pressure sensor? or abs module?



does this sound right to you guys? anyone with this particular experience before?


UPDATE: just noticed my oil level is extremely low. im thinking that this is effecting the brake booster vacuum pump (hence why its acting weird only when engine is on). so going to Walmart to cop some oil and top it off and check back on this. hopefully this fixes it. I have no oil leaks but engine eats up oil. Must have bad piston rings or something... anyway, will be back with an update soon.


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2006 e53 3.0i

Verify which brake fluid is required for the X. On my X I use DOT 4 fluid. Most cars use DOT 3.

[mikesoops]

OK! UPDATE!

Master cylinder needed to be replaced! I Paid $500 to get the job done with OEM warranty parts and service.

the end.