Brake booster Non-return valve

sprint750 · #1 (**permalink**) 06-15-2008, 10:01 AM

Hello,

I am currently rebuilding the brake system on one of my my early 105 ('67 Super, single circuit with hydraulic brake booster).

I was just wondering about the non return valve, screwed on the inlet manifold.

The valve is definitely stucked open. You can blow throught in both directions.

Name: collecteur adm.jpg
Views: 152
Size: 44.5 KB

I've been using this vehicle as a daily driver for 7 years now and never noticed any problem, brakewise.

Could somebody explain what is the task of this non return valve and if there is any risk if this item is not working properly.

Any input will be appreciated

Regards
Sébastien

rafael · #2 (**permalink**) 06-15-2008, 02:14 PM

This valve is allows air to move away from the brake booster. The result is that you get a certain level of under pressure in the booster, so that you have assisted brakes.

If this valve is not working then the brake assistance is related to the under pressure in the intake manifold. This under pressure depends on the revs of the engine. If the engine stalls, then there is no under pressure, hence no brake assistance.

However, even without brake assistance you should be able to brake, you simply have to press the brake pedal harder.

**Gubi** · #3 (**permalink**) 06-15-2008, 02:27 PM

Those valves are usually pretty simple internally. I bet if you give it a good cleaning with intake cleaner you can get it working properly.

**101/105guy** · #4 (**permalink**) 06-15-2008, 03:14 PM

Also, note that if you have a backfire in #4 cyl. it might destroy the booster!!

sprint750 · #5 (**permalink**) 06-15-2008, 03:53 PM

Quote:

Originally Posted by Gubi

Those valves are usually pretty simple internally. I bet if you give it a good cleaning with intake cleaner you can get it working properly.

**papajam** · #6 (**permalink**) 06-15-2008, 04:07 PM

Quote:

Originally Posted by 101/105guy

Also, note that if you have a backfire in #4 cyl. it might destroy the booster!!

**Anfanuts** · #7 (**permalink**) 06-18-2008, 09:26 AM

Centerline sells a replacement for this manifold screw-in type CV. They do not have a Series 1 banjo-type check valve. I am fiddling with retrofitting the screwed CV into a banjo fitting now for the earlier cars.

**davbert** · #8 (**permalink**) 06-30-2008, 01:49 PM

anyone know what size and thread pitch it is? i want to find a bolt to plug up my manifold.

thanks

db