Stiff/hard brakes before start in the mornings. Please help...

Jhill · 07-22-2016, 01:59 PM

Does it go back to normal as soon as the vehicle is started? If so you are looking at the brake booster check valve. The booster is supposed to maintain vacuum for about 3-4 pedal depresses after engine off. If it can't hold this then first place to look is the check valve in line with the vacuum hose.

To comment if possible leaking hose, this would cause a vacuum leak, poor idle and lean mixture code so that's not likely.

Also if it does go back to normal as soon as engine starts and is running then you are ok to drive, your not losing your brakes it's just loosing assist after its sat. So as long as your engine doesn't die you'll still have assist while driving. Not the safest scenario but not and OMG I need to tow it to the shop scenario either.

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07-22-2016, 01:59 PM	#6 (permalink)
Jhill Track Member Join Date: Mar 2016 Location: San jose Posts: 854 Drives: 2013 370z sport Rep Power: 3385	Does it go back to normal as soon as the vehicle is started? If so you are looking at the brake booster check valve. The booster is supposed to maintain vacuum for about 3-4 pedal depresses after engine off. If it can't hold this then first place to look is the check valve in line with the vacuum hose. To comment if possible leaking hose, this would cause a vacuum leak, poor idle and lean mixture code so that's not likely. Also if it does go back to normal as soon as engine starts and is running then you are ok to drive, your not losing your brakes it's just loosing assist after its sat. So as long as your engine doesn't die you'll still have assist while driving. Not the safest scenario but not and OMG I need to tow it to the shop scenario either.