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Discussion Starter #1
sorry for the noob post, but I searched.
after my 06 4cyl manual, sits overnight, the brake pedal is rock hard.
after i push in the clutch, i have to push almost as hard as i can on the brakes to keep the truck from moving.(very very mild incline).
however as soon as i start the engine, the brakes work perfectly.
I have no other bitches about the brakes than that.
I called the dealer to explain the issue, and i quote " oh yeah, those do that all the time in the winter, its normal"
its only got 2100 miles on it and ive had it since late october. im pretty sure any issue ive had started about 400 miles into ownership, so the test drives didnt show any negative results.
any advice would be helpful.
hoytoyota
 

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For once, what the dealer advised is correct. If you press the brakes when the engine is off, it builds pressure in the braking system. When you fire up the engine, the brake assist kicks in and allows you to freely use the brake pedal.

For whatever reason, the cold temperatures are causing pressure to build up on its own; nothing to worry about.

Sit down in ANY car with the engine off and pump the brake a couple of times, the exact same thing will happen.

Maybe somebody else will chime in with a more technical explanation.

Welcome to TTORA
 

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Discussion Starter #3
I understand what you mean about pumping the brake to get it to firm up.
but I dont even touch the brake. until im ready to start the truck.
ive just never had this feeling in the brakes (without pumping them up)
it just seemed odd. only one guy over at toyota nation had the same problem,
but his went away on its own. Ill just hope for the same.
 

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hoytoyota said:
I understand what you mean about pumping the brake to get it to firm up.
but I dont even touch the brake. until im ready to start the truck.
ive just never had this feeling in the brakes (without pumping them up)
it just seemed odd. only one guy over at toyota nation had the same problem,
but his went away on its own. Ill just hope for the same.
The post right before yours (from Flexon) said that cold air will cause this same effect, he did not say you are pumping them. Much like the dealer said. Its brand new man, just take it in and let them check it out. They will probably tell you the same thing. As long as they function correct when its started thats all that matters anyway.
 

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My truck has almost 20k on it and my brakes do the same thing. I don't need to pump the brakes to get pressure built up with the engine off. With it on, they work perfectly fine because of the vacuum assist and whatnot. If you search for my old post, I mentioned this because it prevented me from bleeding the brakes without the engine on. I'm not really sure what the concern is.. I don't usually need to brake when I'm not going anywhere anyway..??
 

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OK, so there's this big round can on the back of the master cylinder. You've seen it.

Inside that can is a diaphragm.

When the engine runs, the vacuum from the intake manifold is used to pull a vacuum inside that big can.

When you step on the brake pedal, there is a valve that opens and puts the vacuum on the diaphragm. This pulls the brake pedal down and helps you by applying pressure for you.

When the motor is off, that can should hold enough vacuum for at least one stop. Pumping the pedal will use up the vacuum, and then the pedal feels hard.

If the vacuum is gone overnight, then the system is leaking. It could be the check valve where the big vacuum line goes into the can, or the valve that makes it work.

Regardless of the cause, it's not supposed to leak.

I would make them go out to the lot and show me that all the new trucks have no vacuum in the brake system before I would accept that "They all do that".

I know that my '05 holds vacuum overnight regardless of the temp.
 

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Discussion Starter #8
thanks guys , a leak in the system makes sense, I probably wouldnt even care if i knew for sure, it wont cause problems down the road. I just want to make sure its safe....my 2 year old rides with me every morning. ( shes my main concern)
 

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It's not right the way it is..Do just what a previous poster said, have them show you some on the lot that do the same thing.
 

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You'd think that you could depend on a call to the service dept. What a shame. Instead the guy needs to make posts on a forum to get reliable information. I just generally don't trust techs to give you info and help you out. It's like they resent you giving a crap and taking interest in your vehicle and ultimately their profession.
 

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Discussion Starter #11
quick update, I called to talk to a tech (instead of the guy at the counter), he said it should not do that.
they tested it out after sitting overnight, they decided to order a brake booster for it to see if that fixes my problem.
Ill update the post when theyre done.
also , i just wanted to say thanks.
 
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