View Single Post
  #63  
Old 9th March 2010, 06:37 PM
Jaglavak's Avatar
Jaglavak Jaglavak is offline
Wrench Bender
 
Join Date: Mar 2009
Location: PNW
Posts: 53,734
Quote:
Originally Posted by HongKongFooey View Post
Toyota's safety bulletin also mentioned depleting the vacuum assist. Are you able to shed some light on how that works? I'm not much of a car guy and mentions of the vacuum assist have been showing up a lot. I've been assuming they mean some kind of venturi but that's just a WAG I make while reading.
The power assist for brakes comes from engine vacuum. It's the big metal can about the size of a stubby cookie jar between the master cylinder and the firewall. Yes, I'm hungry. Notice the big thumb size hose leading from that to the intake manifold.

When the engine is WFO, engine vacuum goes away. It's hardly ever a problem because normally you would never step on the gas and the brakes at the same time.

The car has a vacuum can with check valves for these situations. Mostly intended for if you lose the engine. It stores enough vacuum for about one or two good stomps. You still have brakes after the vacuum can is depleted, but just no power assist. Then you might want to use both feet on the brakes.
Reply With Quote