Chevy & GMC Vans

I have the flapper thing in the snorkel of the air cleaner housing.
You know the thing that diverts the intake air from either the
manifold pre-heat hose or from the regular air intake. It is
not the style that has a vacuum hose attached. It's the
simpler kind with a spring, heat actuated.

Is that thing adjustable? Can I make it open earlier (cooler)?
It's staying closed at 104F (measured with my laser thingie)
and seems to be causing rough idle and stalling. Removing
the preheat hose eliminates the problem. But I think I
need the hose in place to pass smog.

Thanks


Lump

Take the hose out drive the van all year then when it comes time for smog put the hose back in. Take the test pass then remove the hose so the truck drives properly. The other thing you can do is jam the flap open. The old mechanical diverters fail after a while.

Kidhauler wrote:Take the hose out drive the van all year then when it comes time for smog put the hose back in. Take the test pass then remove the hose so the truck drives properly. The other thing you can do is jam the flap open. The old mechanical diverters fail after a while.

Thanks. Suggestions on how to jam the thing open?

Lump

I have heard that exessive force and a screw driver will work or pull the guts out of it using the same method. If you remove the butterfly inside then you can leave the tube in place and it will still look good to the smog test guys. Trust me I used to be an acting assitant manager in the test up in vancouver. No one will look inside the valve to see if it is there.

OK. I found a way to modify the thing so that it will open at a lower temp.
I'm not really interested in blocking it open and violating the law. Plus
it actually does get something like cold here in Phoenix in the winter,
maybe around 40 degrees. So I might actually want it to do the
job it's designed to do, at least for a couple of days out
of the year.

I cleaned it up a bunch with brake cleaner spray and stretched
out the little spring that holds it in the closed position. Then to
test it -

I sprayed it with some of that compressed air in a can, like
you'd use to clean your computer keyboard. That stuff gets
really cold, esp if you shake the can. That brought the
metal down to about 50 degrees (using a laser/infrared
thermo thing to read the temp). Then I used my heat
gun (for heat shrink tubing) to warm it up till it opened.
I was shooting for 80 degrees. I was able to get it to
open at 78. Pretty darn close.

So if anyone else finds themselves troubleshooting a
rough idle/stumble problem, perhaps that will help.
Check the operation of that preheat thing.

Thanks kidhauler for the original suggestion to check
the heat riser tube.


Lumpy

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Yes but no blue notes. Just blue hairs.

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