starting the car/brake question...

[QCTLG]

I was just wondering if anyone else V8/Tech behaves like my car for the following:

When I start my car in the morning, after it sat all night, my brake pedal is VERY HARD to press. In fact it will only move about a 1/4 to 1/2 inch and I must press REALLY HARD for it to move.

Is anyone else having the same thing?
I'm wondering if this is normal.

Many thanks in advance

 

[Pwrplay]

Mine does the same thing here. I don't think there is any concern.

 

[rb cline]

QCTLG

I would suspect the vacuum brake booster assby. first. It could be the vacuum line to it has a leak, the 1 way valve that keeps it from bleeding down after engine shut off is defective or the vacuum bladder itself is leaking.
With any one of these problems you could have no brake vacuum boost on a cold start but after a few seconds of applied engine vacuum things appear normal, but they are not. Sooner or later the condition will get worse and sooner or later you could experience loss of power assist braking. Not good!
Hope this nails it. Lat us know what you found out.

Regards RBC

 

[Pwrplay]

Can anyone else advise if their Genesis brake pedal is hard to depress on cold start? Mine has been like this since day 1 which is about 1 1/2 months now, and if it is a potential problem I'd like to get it fixed ASAP before it becomes a bigger problem.

 

[QCTLG]

QCTLG

I would suspect the vacuum brake booster assby. first. It could be the vacuum line to it has a leak, the 1 way valve that keeps it from bleeding down after engine shut off is defective or the vacuum bladder itself is leaking.
With any one of these problems you could have no brake vacuum boost on a cold start but after a few seconds of applied engine vacuum things appear normal, but they are not. Sooner or later the condition will get worse and sooner or later you could experience loss of power assist braking. Not good!
Hope this nails it. Lat us know what you found out.

Regards RBC

WOW...just got back and read this...this is very scary!!!
Please people if anyone else can reply and let us know if your car does the same thing.

FYI mine has been like this since day 1 and that's 5 months ago!

Thanks in advance

 

[TJPark01]

WOW...just got back and read this...this is very scary!!!
Please people if anyone else can reply and let us know if your car does the same thing.

FYI mine has been like this since day 1 and that's 5 months ago!

Thanks in advance

That's not normal, take it to the dealer. I have a V8, not tech, but that shouldn't matter when it comes to brake system. The pedal is very easy to press. In fact, I go to the beach a lot and often drive with bare feet when I come back, and I routinely press the brake with my big toe to start the car. If you have to press the brake hard to start the car, something aint right brother.

 

[Pwrplay]

My pedal is easy to move, but it only depresses about 1 inch or so first thing in the morning.

I just went and tested it now after sitting for an hour and the pedal depresses about half way down.

To replicate the way the pedal feels in the morning, I have to pump the pedal a few times to build up pressure.

I wonder why its like this after sitting over night?

 

[mikec]

My brake pedal travels very little after the car has sat for a couple of days; the vacuum assist certainly bleeds off. It takes more than overnight though to bleed off; at least two days for my car. When it has lost all vacuum assist, I still don't have to push hard though to get the car to start; no harder than I need to press when the assist is working fully. Just a light push on the pedal is enough.

The vacuum assist, in theory, shouldn't bleed off. On my other cars (non-Hyundai) the vacuum assist remains for several days - my Genesis is certainly the fastest at loosing the vacuum. As long as it takes more than several hours though it's not a safety issue. The safety issue is:
* driving at normal or high speed
* something happens (fails) and the engine stalls. You need to brake now.
* as long as the power assist doesn't bleed down instantly, you should have decent braking performance. On most cars, the vacuum assist mechanism stores enough vacuum for at least two full applications of the brakes. If the vacuum assist bleeds down too quickly, you'll have to really stand on the brake pedal to stop the vehicle.

The typical mechanic's test of the power brake vacuum booster:
1: Start the engine and let it idle for a minute or so. This "charges" the booster with vacuum. In reality, it should need only a second or two of idling to fully build up vacuum

2: push the brake pedal with moderate force, note how far it travels. Engine is still idling. Release and let the engine idle for a few seconds to re-charge the booster.

3: turn off the engine.

4: Once the engine has stopped, push the brake pedal again, same force as step 2. The travel should be pretty much the same as step 2.

5: lift off the brake for a second, then push again. Same force again. The pedal travel should be nearly as far as steps 2 and 4. If it's significantly less, the reserve capacity of the brake booster is suspect.

6: lift off the brake pedal again, then press again, same force again. The travel will probably be quite a bit less this time; that's normal/expected. If the travel is still as large as step 2, your car either has a mega-booster or you are not pushing hard enough in these tests - start over with a bit more pedal force.

7: lift off, then re-apply one more time. There will probably be little to no assist this time. Repeat the lift - re-apply a few times to make sure all assist is gone. The pedal travel will be pretty small now for the same force. It should travel further though if you really push on it.

8: push the pedal firmly, and hold it, while starting the engine. As soon as the engine catches, the pedal should sink quite a bit as fresh engine vacuum replenishes the vacuum assist mechanism.

Steps 4 and 5 are the biggies in this test: if the pedal travel is still pretty far in step 5, the booster is doing its basic job. In theory you shouldn't need to "hold" vacuum for more than a minute or two... how long do you plan to coast with no engine without trying to stop? If the booster has a big leak, or if the check valve that traps the vacuum fails, the pedal travel in steps 4 and 5 will show big differences. That's bad.

mike c.

 

[QCTLG]

Mike c.

I followed your instructions to the letter and it behaved EXACTLY as you describe in all your steps. So all is normal.

It's unfortunate that not very many people are responding with this simple test but I am worried that something is definitely wrong.

Pwrplay is dead-on...It's like someone enters my car during the middle of the night and pumps my brake to death and when I first start the car in the morning my brake pedal is VERY HARD to move! It barely moves!

Immediately after starting the car it travels all the way back. If a go see a customer and park it for half a day, come back and start the car, the brake pedal has normal travel.
But after sitting all night it hard as hell.

I don't think it's normal from some of the responses here.
I've NEVER had this with any other car I've owned

should I take it to the dealer to check?

Thanks again

 

[Pwrplay]

after reading mikec's post , I am not nearly as concerned, as I now recall some of the info in his post back from my high school auto class. ( a looong time ago) . if it seems to happen increasingly sooner, then I'll get it looked at.

Thanks for the refrsher course on brake boosters Mike

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[mikec]

should I take it to the dealer to check?

Thanks again

I wouldn't make a special trip to the dealer just for this but do have them test it on your next regular visit. As long as it holds vacuum for a few hours there is no safety issue. Maybe have the sales guys let you sit in the cars in the lot/showroom and see how many have firm pedals. My dealership was very good about letting me compare other cars to mine when I had a question about the audio quality. The showroom car has probably sat for a couple days without being driven so it will probably have a rock-hard/no-travel pedal.

mike c.

 

[dashrr]

Your car is most likely operating as designed. The problem is, it wasn't designed correctly! As the engines become more and more fuel efficient, less vacuum is available to operate systems such as the brakes. Low vacuum during a cold start is a common problem --especially w/direct injection or VVT type engines. Ford seems to use a vacuum aspirator to adress the issue on many of their vehicles and GM has installed auxillary vacuum pumps on some of their vehicles. You can find GM technical service bulletins and recalls where electric vacuum pumps have been added to adress the issue on Saturns and the Cadillac CTS. The problem will be worse at higher altitudes as even less vacuum will be available. The best advice I can give you is to let your vehicle run at idle for 60 to 90 seconds before you take off and need to use the brakes in the morning. The vacuum issue should diminish/disappear given sufficient time for the engine to warm up.

 

[ctrcbob]

If I let my car sit overnight, or even for three days, the brake goes down normally.

If I let my car sit for two weeks, like I did when I went up North with my wifes Continental, on my return, the brake was rock hard, and hardly went down, until the car started.

You may want to get yours checked, although I don't think it is safety issue.

 

[ASHDUMP]

My brake is rock solid in the morning or if the car has been sitting for a while. I never have a problem starting it though. After the car is started (1 second) the brake functions normally.

 

[TruRed1]

My brake is rock solid in the morning or if the car has been sitting for a while. I never have a problem starting it though. After the car is started (1 second) the brake functions normally.

I'm in this camp with my '09 4.6 Tech. Heck, I thought it was normal for the brake to not depress more than a 1/4" in the morning! As long as it starts is all I'm worried about. Perhaps one more reason I'll be visiting the service department with this vehicle. Argh.

 

[RedHot2011]

Yes, I have a 2011 Genesis 3.8 Coupe and I started having that problem about 2 weeks ago. If the car sits for more than an hour, the brake pedal gets rock hard and it's hard to push down to start the car. Talked with the service writer about the issue at my local Hyundai dealership - he thinks it may be a vacuum leak but I would have to leave the car for a day. Not sure when I want to deal with the annoyance of leaving the car with people I have no confidence in. I also have an issue with the car doors not opening when I push the button on the handle and with the starter getting stuck when I start the car (it keeps trying to turn the car over but it never starts), I have to shut off the car and start over and then it starts. Very frustrating issues with this great car.

 

[mikec]

The brake power assist is a vacuum booster assembly - basically the huge round thing bolted to the firewall, the brake master cylinder then bolts to the booster. The booster uses trapped engine vacuum to help apply pressure to the master cylinder when you push the brake pedal. There is a fairly large vacuum hose connecting the booster to the engine... and somewhere in this hose, or right at the booster itself, is a check valve: think of it as a one-way hose. This check valve should let air flow towards the engine (i.e. developing vacuum in the booster) and should NOT let air flow towards the booster (no cancelling any accumulated vacuum) so the vacuum is maintained even when the engine stalls. There should be enough "trapped" vacuum in the booster to stop the car twice (without needing excessive brake pedal force) even with the engine stalled/off. It's common for the vacuum to bleed down over a day or so, but bleeds down after only an hour? Sounds like either the booster leaks, the check valve doesn't check, or the hose between the booster and check valve has a leak. Get it fixed soon; such issues can easily develop into much larger leaks = little brakes in an emergency.

mike c.

 

[sreps]

I'm having this issue on my 16 Ultimate for a couple weeks now. Had the car for about 18 months and she has about 16,000 miles. Stiff brake after sitting for a couple hours. Dealer said it's normal operation. But why is this all of a sudden the normal operation after 18 months? I've been driving 35 years. Drove hundreds of different cars when considering my cars, family cars, friends cars, rentals, loaners, etc. Never had this happen. It ain't normal! Called dealer and insisted that they're not going to pencilwhip this one.

 

[aksolar3]

Does anyone have any idea if the mechanic who said I need to remove the valve cover on my 09 Genesis 4.6 to replace the brake booster?! Please help

 

[Gunkk]

Yes, on the 4.6 the valve cover has to be removed in order to change the brake booster.