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Discussion Starter · #1 ·
Replaced my opti vent tubing with silicone and want to replace the valves on the tubing. The tubing that runs from the drivers side of the intake to the opti has 2 inline devices.
The device closest to the front is an air check valve that prohibits air to back flow from the intake into the opti. I bought a replacement for this valve.

There is another small plastic inline device (maybe it is a filter or restrictor?) on this tubing closer to the side of the intake where the tube attaches to the intake.

What is that?

I want to replace that device also but do not want to buy a full vent harness.
 

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yes, the part is a combo restrictor and filter so the opti doesnt turn into a full blown vacuum leak and debris sucked into the intake.
 

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Discussion Starter · #4 ·
I think those devices are reveresed

I tested the OEM valves on my car. The one closest to the opti seems like it was a one way valve, you could blow air through one side but not the other. The other valve closer to the intake manifold seemed to be a restrictor that was limiting the amount of air passing back into the intake manifold.
The purpose of this is to look for a replacement of these lines and valves. The Dealer wants $80 for this set of hose and valves.
I think these hoses and valves could be fabricated from other sources for under $10 if we can find the restrictor from an aftermarket source. I believe Dorman makes a back flow valve that can be used. I ordered one through AA ($5) and will advise back once I see if it fits.
 

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I tested the OEM valves on my car. The one closest to the opti seems like it was a one way valve, you could blow air through one side but not the other. The other valve closer to the intake manifold seemed to be a restrictor that was limiting the amount of air passing back into the intake manifold.
The purpose of this is to look for a replacement of these lines and valves. The Dealer wants $80 for this set of hose and valves.
I think these hoses and valves could be fabricated from other sources for under $10 if we can find the restrictor from an aftermarket source. I believe Dorman makes a back flow valve that can be used. I ordered one through AA ($5) and will advise back once I see if it fits.
I think the backflow valve can be source off of Turbo Buicks for around 7 dollars for GM parts, if the line size 7/32". I also think the filter may be found for around 10 dollars from the vaccum light covers on 67-ish RS Camaros. I've not actually bought any of these parts yet, just been researching.

- Brian
 

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Discussion Starter · #6 ·
I think the backflow valve can be source off of Turbo Buicks for around 7 dollars for GM parts, if the line size 7/32". I also think the filter may be found for around 10 dollars from the vaccum light covers on 67-ish RS Camaros. I've not actually bought any of these parts yet, just been researching.

- Brian
Thanks for the input Brian. Post up if you can find the part numbers.
 

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One of our members - POPIMPIN CUSTOMS I.N.C. made a replacement harness. You might want to contact him for directions.
 

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Even $50 is way too much for this thing!

Anyone remember what Dal Slabaugh charged for this before he retired?
Not from Dal, but I found one at the beginning of the year for $24 + shipping! It was from eBay/Hamilton Chevy, but the prices are now double what I paid.
 

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Discussion Starter · #10 ·
We gotta find a replacement

I called my local GM dealer today and with my discount it was $64.55 plus tax. That is absolutely ridiculous.
I will report back if this Dorman valve fits the vent line.

I found this stainless check valve from China on Ebay.

We need to analyze the filter/restrictor to determine the correct air flow/restriction.
 

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Discussion Starter · #11 · (Edited)
Dorman valve fits

This Dorman valve fits. It can replace the one way check valve.

Dorman - OE Solutions Vacuum Check Valve Universal - 47149


$4.99

We need to fabricate the restrictor/filter. Anyone have any ideas. How much flow needs to be restricted?
 

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This Dorman valve works. It will replace the one way check valve.

Dorman - OE Solutions Vacuum Check Valve Universal - 47149


$4.99

We need to fabricate the restrictor/filter. Anyone have any ideas. How much flow needs to be restricted?

yeah screw chevy and there $60 for a new one.... i need to get some new filters for my homemade harness lol
 

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A cigarette filter might work. LOL
:)

If their opti fails due to some Jerry rigged set up, $60 bucks will seem like cheap insurance.

I hate paying for something that doesn't seem priced fairly but time is $ and I'd end up paying $500 if I devoted the time in trying to build one versus making $.

I hope they can do it though and sell a bunch of them for $25 bucks.
 

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:)

If their opti fails due to some Jerry rigged set up, $60 bucks will seem like cheap insurance.

I hate paying for something that doesn't seem priced fairly but time is $ and I'd end up paying $500 if I devoted the time in trying to build one versus making $.

I hope they can do it though and sell a bunch of them for $25 bucks.
Come on guys, let's come up with $15 vent harness. All we need is an accurate vacuum meter, new harness and some work to test homemade modifications.
 

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I just offered $40 bucks for one. I don't even need one [and my car still isn't even drivable ~ unrelated issues] as mine is new but for $40 bucks I figured it was worth it as a spare so I'm really no help with a price point perspective.

I'll offer my support as I wouldn't have a clue where to start otherwise.
 

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need to find out what the orifice size is on the restrictor, might be under the part specs or in the fsm.
or take one apart and see.
 

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I just took apart a V&V Harness ... for which I paid ... $50 ... plus $15 shipping ... :eek: ... :mad:

All the plastic orifices are the same size: 3/32" ID.

Using unexceptional lung power, I pulled and pushed air manually and individually, through each CHECK VALVE.

The larger of the two CHECK VALVES either contains (more likely), or is (less likely), the filtration media; based on the greater difficulty in pulling and pushing air through it (that, and I can't see through it either.

I could neither pull nor push air through either of the two CHECK VALVES 'from blue to white'. BOTH CHECK VALVES only permitted air to pass 'from white to blue'.

The filter on 'shoebox's V&V Harness is only solid blue, not twotone white & blue. Maybe his was merely a filter/flow reducer, but on mine, it's one of two CHECK VALVES.

1)
That neither explains nor justifies the egregiously brazen and ridiculous markups.
(I've heard of Lexus charging $800 for a CMOS battery, by the way, so I'm not surprised, just angry.)

2)
Though I'll admit that it doesn't answer the question of how much flow needs to be restricted ... how many combo CHECK VALVE/filter/flow reducers of that specific physical configuration could there really be?

3) Since it's apart ... with what, and how, do I test the check valve/filter/flow reducer's restrictive value?
The write-up Henry '06 was referring to will answer your questions:

"...If you don't find yourself replacing the harness, there is a way to clean the piece that causes the most problems: the pinhole check valve.

Before I explain that, please note that there are two check valves in this system. The first is located closer to the intake manifold on the driver's side. The vacuum line attaches to a nipple on the side of the aluminum manifold and runs to the first check valve. This first valve is called a "one way" valve (#1 in the diagram above). It typically doesn't go bad very often. But it should be inspected as well. If you blow through it, air will only go one way.

The second valve in the chain (the pinhole valve, or GM calls it a filter) is the one that causes the most problems. This is #2 in the diagram above.

It is located about here, though it could be further back toward the intake manifold on some cars. I've relocated/unburied mine since I like to check on this and keep it clean:

Remove it from the vacuum line by giving each tube a tug on each side.

Once removed, it looks like this. Note that one end is open plastic, and the other has a metal insert/collar as shown. This side is actually the location of the pinhole.

You can hold the valve up to a bright light source to inspect the pinhole. You should see a small point of light pass through as shown.

If light does not pass through or you feel like cleaning it anyways, then stick a very small pin or piece of wire. In this example, I stripped a twisty tie. Even that was a little too thick. A pin or a needle with a sharp point is best for this job. "


What I do not understand is how a pinhole can act as an unidirectional check-valve.
 

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What I do not understand is how a pinhole can act as an unidirectional check-valve.
I don't believe its a check valve so much as its a restriction orifice.

The check valve is one way and is the check valve.

The second part is the pinhole and is just a flow restrictor. It works exactly like restrictor plates in Nascar.

And rather than dig our my fluids text books I'm going to leave it at that.

- Brian
 
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