Admittedly this is not specifically for my Cobalt, but I figured it's applicable to all cars and this seemed the best place for it.

On Saturday I replaced the brake booster in my Tiguan. Everything went as well as I expected; however, when I test drove it I noticed the brakes were extremely stiff. I also noticed that when the trans was in "park" it acted totally normal. Back to "drive" and it's like there's no booster. The brakes themselves work great, just no or little boost. I think the brakes are activating before the booster has a chance to provide boost.

I don't think the booster or vacuum pump can tell when the car is in park or drive, so I don't think the problem is vacuum-related. The two theories I have are: 1) the pushrod is not aligned in the master cylinder causing the cylinder to be actuated too early, or 2) I bled them with the parking brake on, and when I released the parking brake it added fluid/pressure into the lines.

I'm mostly wondering if the second theory is even possible? I would think that a fluctuation in fluid would just go into the reservoir. The caveat with that is that the brake pedal must be pushed in order to release the parking brake (it's an electric motor on the calipers). Either way I'm checking it all tonight.

 

step 1) get a gasoline
step 2) get a match
step 3) dump gasoline inside and outside
step 4) light match
step 5) enjoy the fire

 

You forgot the marshmellows

 

 

wasnt sure if he would like plastic flavored marshmallows or not so i figured id just leave that out haha

 

You have no idea how many times I've been tempted to do that with this car. It's so bad that I'm now saying that my Cobalt is "reliable" even after the freaking engine died in it.

 

thats why i said that lol. i knew youve been having problems with it so it just fit because its one thing after another lmfao

 

If/when this gets fixed it's gone. I have a buyer lined up who has already gotten a loan ready for it. I said that since the part was already coming I'd take care of it. I should have known better than to think this would be a straightforward R&R.

 

Now that I say that the "really easy" low pressure pump is going to give me fits too. I said I'd fix that as well (since the part was coming).

 

However none of this conversation is anyone saying "this totes happened to me and it was extra pressure in the lines" like I wanted to hear.

 

was there a vagcom requirement to cycle things to bleed the system correctly

 

There is, it is for removing fluid or air from the abs pump. My dad mentioned he had some air in his Golf's brakes after bleeding forever, and I mentioned that procedure. He said he ran it till his leg was dead.

I tested it a little more and decided it's working just a little stiff. I'm not going to disassemble it.

 

Get a pressure bleeder, best purchase I made. It would be better if the fluid would transfer from the pressure tank into the brake fluid reservoir better but it still makes things go quick. I've read you can modify the pressure bleeders to transfer the fluid better but I haven't made the modification to mine.

 

I tried hooking up my hand-held vac pump but nothing happened. Is there an advantage to a pressure bleeder over someone pumping the brakes while you operate the bleeder valve?