2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
Sponsored by:

Check valve in brake hose from manifold to hard line?

Thread Tools
 
Search this Thread
 
Old 10-14-21, 11:27 PM
  #1  
Listen to King Diamond.

Thread Starter
iTrader: (4)
 
need RX7's Avatar
 
Join Date: Dec 2006
Location: Sterling Heights, MI
Posts: 2,832
Received 6 Likes on 6 Posts
Check valve in brake hose from manifold to hard line?

I'm aware that there's a check valve in the rubber hose that connects the brake booster to the hardline on the fire wall. I have a JDM S4 TII engine, and the rubber hose running from the lower intake manifold to the hardline seems to have a check valve in it too. It also has an arrow with 'to engine' printed on it. If I blow into the hose in the direction of the arrow I get airflow, no airflow the other way.

Is there supposed to be a check valve in both hoses on each end of the hardline? Do RHD cars have just the one hose and no hardline? Can I just replace the manifold-to-hardline hose with a regular one as long as I have the check valve in the booster hose?
Old 10-15-21, 05:55 AM
  #2  
Have RX-7, will restore


iTrader: (91)
 
mazdaverx713b's Avatar
 
Join Date: Oct 2003
Location: Ohio
Posts: 21,713
Received 1,053 Likes on 892 Posts
You need the check valve to prevent vacuum loss from the booster back into the intake manifold. The brake booster is vacuum assisted and is fed the required vacuum from the intake manifold. The check valve prevents pressure loss when there is no supplied engine vacuum. This would be in the event needing to stop after the engine has stalled. Typically the booster will store three pedal strokes worth of vacuum pressure.

There should be one check valve and it should be close to the booster. You can replace the booster vacuum line with a standard high quality rubber hose but keep in mind that the original hose is a molded hose. You will of course have to transfer the check valve and it will have to go in the original location it was in.
Old 10-15-21, 08:26 AM
  #3  
Moderator

iTrader: (3)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,835
Received 2,604 Likes on 1,847 Posts
Originally Posted by need RX7
Do RHD cars have just the one hose and no hardline?
that is it right there. RHD car the hose just makes a ? and hooks to the booster
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
mr_vaughn
2nd Generation Specific (1986-1992)
15
10-30-19 07:47 PM
GrossPolluter
2nd Generation Specific (1986-1992)
5
02-28-14 12:40 PM
TheWoganSleeve
3rd Generation Specific (1993-2002)
6
01-17-07 12:46 PM
Valkyrie
2nd Generation Specific (1986-1992)
4
03-29-06 04:11 PM



Quick Reply: Check valve in brake hose from manifold to hard line?



All times are GMT -5. The time now is 11:00 PM.