What is this Vavle for

[shambles]

Hello,

What does this valve do, and where should the vacuum line be routed? It's capped off as you can see. It's on bolted toward the back of the intake Manifold. This is a 250 Inline 6.

[IMG][/IMG]

[Warrens69GMC]

Egr valve, allows exhaust into the intake to reduce emissions.

[shambles]

So I would loop a vacuum like back to the Carb somewhere? It's not a big line, maybe 1/4".

[Warrens69GMC]

You would want to run a line to a ported vacuum source.

[Dead Parrot]

If the emission sticker is still on the radiator support, it will tell you where the vacuum line goes. Sometimes they route thru a temp sensor on the t-stat housing.

Otherwise post up the year and maybe someone will post a pic of a sticker.

[shambles]

Oh yeah, its a 1978 GMC C15. I don't have the sticker. There isn't a temp sensor on the housing. There are two blocked off plugs. They're painted blue to match the Thermostat Housing. It's possible it was removed.

[kwmech]

Do they have emission testing in your part of the state for this year of truck?

[cadillac_al]

A lot of people just bypass it

[shambles]

Maricopa county (Greater Phoenix Area) actually does emissions testing. Looks like the P.O. bypassed it by plugging it off. I'd like to attempt an emissions test soon. I'll probably need to connect it for testing purposes.