How to test Diverter Valve

[Buckeye]

Like to understand how 3 ports Blow Off (BOV) Valve 11721260088 works  and how to test one for proper operation?

 

Edited December 17, 2019 by Buckeye
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[Buckeye]

n/t

 

Edited December 8, 2019 by Buckeye
duplicate

[Conserv]

1 hour ago, Buckeye said:

Like to understand how 3 ports Blow Off (BOV) Valve 11721260088 works  and how to test one for proper operation?

 

 

You and me, both!

 

Best regards,

 

Steve

 

[Mike Self]

Is that what's commonly termed the "gulp valve" and used in the emissions plumbing on air pump equipped 2002s?  If so, it's a GM (Chevy, IIRC) part so you should be able to track down how it works from a Chevy web site. 

 

mike

[TobyB]

It's not the gulp (one way) valve, it's something after it.

 

What's odd is that there is no obvious control going to it-

 

those valves are usually vacuum controlled, or modulated, at least.

So I'm guessing it's pressure modulated, as #4 is supposed to only

allow positive pressure in pipe 7

 

t

throws that junk out!

 

 

 

Edited December 8, 2019 by TobyB

[Mike Self]

Sounds like yet another part that needs to take a swim in the neighbor's pool, along with all that other emissions stuff...

 

mike

[Conserv]

Although the parts manual refers to them as blow-off valve, I know them as diverter valves. The valve on my ‘76, I believe, has a single vacuum port, which actuates the valve. But I believe some versions have two ports.

 

Regards,

 

Steve

 

[Buckeye]

On 12/7/2019 at 10:54 PM, TobyB said:

those valves are usually vacuum controlled, or modulated, at least.

So I'm guessing it's pressure modulated, as #4 is supposed to only

allow positive pressure in pipe 7

 

 

 

 

No. 4 is non-return valve, which allows air to CONNECTION PIPE (#3) to exhaust manifold. Therefore valve #4 won't allow air flow backward to hose #7

 

On 12/8/2019 at 1:20 AM, Conserv said:

Although the parts manual refers to them as blow-off valve, I know them as diverter valves. The valve on my ‘76, I believe, has a single vacuum port, which actuates the valve. 

 

Steve thanks for providing better picture. I may have answered my own questions.

Exhaust port on the valve is connected to hose #12 (diagram above), which exhausts to atmosphere 

 

Like to know if anyone have different theory how it works.

 

 

 

Edited December 17, 2019 by Buckeye
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[TobyB]

Yah, with the presence of that nipple, it's not a blow- off valve.  

 

It's just a vacuum controlled air valve.   Blow air from the pump end,

see where it comes out.  Apply vacuum to the small nipple, air should change

from one output to the other.  

 

I'll guess that it usually exhausts to atmosphere, and vacuum on the valve

dumps it into the exhaust manifold- but that's just a guess.

 

t

because cats require EFI for long life.

[jimk]

@Dudeland has the turbocharging bug, but this isn't a blowoff valve for turbocharging.

Here is from the USA supplement manual from 1971.  The valve must be from a later car.

 

 

Edited December 8, 2019 by jimk

[Buckeye]

4 hours ago, jimk said:

The valve must be from a later car.

It is from 1976 car

[TobyB]

Yup- if you stuff the number into the internets, 75- 76 114, E3, E21 and something else, too (maybe Euro E12?)

 

Methinks might come with the ThermalRe-Aktor or similar foolishness.

 

t

 

float- test, float- test....

 

[Mark92131]

1976 Emissions Diagram for CA and 49 State Cars, shows the diverter valve connections to the air pump, Exhaust Manifold with check valve (non-return valve), and vacuum connection to the intake manifold.  What is not shown is the hose that exhausts to the atmosphere.  I believe that Buckeye has correctly identified the connections on the picture of the valve and that #7 hose connects to Air Supply to non-return valve fitting, #14 connects to the Air Pump and #12 connects to the Exhaust Port on the Diverter Valve and vents to the atmosphere.

 

Mark92131

 

 

[Buckeye]

This is correct Mark and thanks for emission diagrams.

[Buckeye]

Upon more research came cross this site talking about Air Injection System in early cars and also provides explanation and differentiation between GULP and DIVERTER VALVE.

 http://what-when-how.com/automobile/air-injection-system-automobile/

 

In my case, I am experiencing backfire during engine deceleration, which perhaps diverter valve not functioning properly when it should. I need to buy me a vacuum tester and check that out.