Hi, I'm a mechanical engineer and I can't spell either.

Back on topic, to the brake engineer, I've always wondered, instead of venting atmosphere to replace the lost air as the brake fluid drains, why don't they have a nitrogen gas filled expansion chamber in there take up the slack instead.

 

Are we still on engineer's not being able to spell, I thought we were over that?

You'll have to be more descriptive to what you mean, because I have absolutely no idea what your speaking about....... brake bleeding?

So we came once again very close to having yet another horrible experience today.... The service rep called me at 4pm that my car was finished..... but of course I still wanted to speak with the manager, but she wasen't around at the time and had to call me back....
I was prepared to go get my car ~5:30 or so, the manager called me at 4:45, and wouldn't you know my car actually wasen't finished because they still don't have the cap... but atleast I give them credit this time by calling me

 

i'm not sure what you mean, but you're not supposed to have air in the brake system at all. it creates a spongy pedal. there is no lost air. they have bleeders that push the fluid in. and the air out. forgive me if this is not what you meant.

 

Sorry, that came out kinda convoluted.

You said "The brake system isn't 'sealed' in the first place, the cap has a vent hole or the fluid would never leave the resevoir and cause a vacuum. "

Basically the atmosphere vents into the vacuum right?

 

I think you have the concept, just not explaining it in a way that I can understand.

If the Reservoir was sealed, the fluid would never leave (unless you sucked it out) because it needs 'something', usually air in this case to take up the volume of the escaped fluid. Just like when you have a 2 liter bottle of coke and you turn it upside down, it creates huge air bubbles that force their way into the bottle so the coke can escape.....

So if you are concluding why some type of compressed gas is not in the system (well cost is always a factor for adding things) so air from the atm. does not take up the void and allow water in the system, it would be a good thought, although any type of 'pressure' would actually apply your brakes and cause drag.

did I understand that correctly?

ANYWAYS~ I got my car back today, this time to make sure there was no fluid on my calipers they washed my car good tactic I think.
I can't actually remember what my cap looked like, but this one is white... are USDM caps white? I think this is a JDM/europe cap or something, USDM parts don't have japanese on them do they? I'm not sure, the reason why I think so is not because it has Japanese but it labels a JIS spec on the cap.
In return for my inconvienence, they agreed to pay for my rental fuel, and the insurance etc... and they also gave me a $200 rewards card for future service... I tried for an entire 60K mile service....at least they could still do my timing belt.

 

Yeah you pretty much got the idea. I'm not too good at explaining my ideas to my boss either.

The positive pressure would be a problem, didn't think of that one.

$200 should be just about good for a stealership tune up!

 

Hate to say it but MOST are loosers who just want to sell brake pads and tuneups! I have worked for mitsu dealer since 92 and have seen mostly idiots! I wouldn't let some of them change the oil in my lawnmower! How hard is it to tighten the drain plug? come on I see it a few times a year jackasses leaving the drain plugs loose!!! Duh enough of my rant! I only will trust 1 guys out of 9 at my dealer!