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Discussion Starter · #1 ·
searching for a vacuum leak and replacing parts related.
Part is Not available anywhere
Is it flow through or one way check valve, and or is there alternative part or can be deleted
Other car don’t have it from what I seen. I’ve removed it sounds empty inside air flows freely.
The hose fitting on the booster I seen for sale come with and without check valve
If so which one do I need?
Thx
 

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1964 camino, 350 Vortec, 700r4
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I’m confused. Why is your vacuum line made of steel brake line? Where does that line come from? Anyway, Air moves 1 direction, and that’s AWAY from your brake booster. Delete that in-line canister section, and replace the 1-way valve on your brake booster. If you can blow both directions through that line, the valve broke. If you plug that line, and press the brake pedal, it should hold pressure. If the pedal moves, or you hear air hissing, your booster itself is bad.
 

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Discussion Starter · #4 ·
I’m confused. Why is your vacuum line made of steel brake line? Where does that line come from? Anyway, Air moves 1 direction, and that’s AWAY from your brake booster. Delete that in-line canister section, and replace the 1-way valve on your brake booster. If you can blow both directions through that line, the valve broke. If you plug that line, and press the brake pedal, it should hold pressure. If the pedal moves, or you hear air hissing, your booster itself is bad.
No
I’m confused. Why is your vacuum line made of steel brake line? Where does that line come from? Anyway, Air moves 1 direction, and that’s AWAY from your brake booster. Delete that in-line canister section, and replace the 1-way valve on your brake booster. If you can blow both directions through that line, the valve broke. If you plug that line, and press the brake pedal, it should hold pressure. If the pedal moves, or you hear air hissing, your booster itself is bad.
stock OEM setup steel line feeds through a support bracket the issue in-line black canister filter, function,,, is it a one way check valve? Because it freely flows both directions. Looking for alternative solution
 

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That is the same set up I have on my stock 350.
The steel line connects to the carb base. If you want to put it back the way it is - I'd replace it. (I did ) I have a NOS Delco filter in a box if you want it. The problem is it is in my storage unit 30 minutes away. LMK
Motor vehicle Electrical wiring Vehicle Auto part Hood
 

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87 Caballero Amarillo, original 305/200-4R, QJ
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It's a check valve. It's part of the manifold-bowl-brake system.

Vacuum is accumulated in the bowl, and the booster, best at low rpm/idle. That vacuum is prevented from bleeding out by the check valve when at high rpm and vacuum goes away.

Without that check valve, you'd have no brakes when suddenly applying brakes from highway speeds. There's a similar check valve on anything vacuum related in GM's that must maintain a certain amount, like ac controls, brakes, headlight doors etc.
 

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Discussion Starter · #9 ·
The white fitting in the booster is the one way check valve. Common part available at local part store.
Canister is nothing more than a charcoal filter to prevent gas vapor build up reaching booster on carbureted engines.
Dorman 80189
So the black in-line filter in pic I posted allows air both ways?
And check valve is mounted on brake booster?
 

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1978 Elcamino base 305
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Valve allows air/ vacuum to travel out of the booster. Test should only let air flow from the hose side when sucked on. No air should flow if you blow into the hose side.
Those are tests with the valve removed from the booster.
Test booster (and valve)
Start engine, apply and release brake.
Turn engine off, Apply brake and release, should feel like normal 2 or 3 times then get firm/hard pedal.
This would confirm valve and booster for vacuum.
One last test. Pump brake 3-4 times engine off. Hold foot firmly on brake, start engine, pedal should fall away from your foot.
 

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1978 Elcamino base 305
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Common way to find vacuum leaks. CAUTION USE COMMON SENCE. HAVE A FIRE EXTINGUISHER HANDY, PERFORM IN AN OPEN AREA.
Using brake cleaner spray a slight amount at suspect areas such as gaskets, vacuum hoses, listen for a chance in rpm/ engine sound.
Do not spray near exhaust manifold or alternator.
 

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Discussion Starter · #17 ·
Thx for your replies all helpful
P/N Dorman 80195 is gonna be a hard find, looked everywhere, not sure if mine is bad, flows air with no restrictions, after further checking brake system isn’t leaking problem is elsewhere. Search continues
Thx again
 
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