Losing vacuum overnight

I am finding that when i get in the car in the morning the brake pedal is hard, with no vacuum reserve. Pedal gets soft after the engine starts. Has anybody else experienced this? Jokes about hard in the morning understood, but not contributory to the discussion. Is there a typical place to check for a vacuum leak at the reservoir?

Lol oh the irony..... but to the serious side.... yeah its normal for brakes to be hard while its not running..... thus “power brakes” thats why its a wonderful feature to go easy on our bad knees.... if no power brakes, you will feel harsh brake pedal to press.


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My 2010 has the same issue although it doesn't do it all the time. I think it has to do with the brake vacuum system not holding the vacuum?

Yes, I believe it is that the brake system is not holding the vacuum. it used to but not any more. Is there a check valve or fitting that is leaking? Not a lot, but just enough to bleed down the vacuum overnight.

I have the same issue. Occasionally the brake pedal is hard in the morning, usually the car can sit for several days and still has vacuum. No pattern I have figured out yet. Been doing this for at least a year.
I’m not too worried.

The check valve is generally at the booster, on the end of the vacuum tube, integrated into the nipple that goes through the grommet into the booster. So either that check valve is randomly not holding vacuum, or the booster itself.

So long as it has proper assist after the engine starts, the brake system should work fine. It would probably be difficult to pinpoint the exact point of failure if it is a slow leak and maybe not consistent. Replacing the tube would be an easier and less costly item to try before digging into the booster.

both my 11's have done this, I can't establish a pattern, perhaps it has to do with having the pedal depressed when you shut it off?

Oilhammer, thanks for your thoughts. I've ordered a new hose (561 612 041C) and I'll get the mechanic to change it out.
Ihatespeed, It's getting progressively worse, used to be overnight, now just a couple of hours and the vacuum is gone.

ahh, mines not nearly that consistent, maybe a few times a month, and more likely after sitting a few days