Dual Diaphragm EGR Valve Question... PLEAS HELP! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TIMSPEED · 03-27-2003, 06:26 PM

Amazingly, in the 1975 model year, it was possible to get a C10 withOUT AIR tubes in the exhaust manifolds, but if you did, it meant you had to have a Dual Diaphragm EGR Valve. Now, since my dad was cool like that, and I have one of these lucky trucks, does anyone know how the dang thing hooks up? I'm pretty sure I've got the top tube hooked up right (to the TVS Switch on the thermostat housing) but as for the bottom..I have no idea...or where can I get a vacuum diagram? HEEEEELP! This is the only thing I need to get done for this truck to pass it's final smog inspection (it becomes smog EXEMPT after it does!)

Mike76251 · 03-27-2003, 06:53 PM

Man, I feel for you living in California.
I love the place but TOOOOOO many laws.
I was raised in Long Beach so I know from where I speak.
That was 30 years ago so maybe I don't (?)

Anyway, off the soapbox.......
Do you still have the emmisions sticker on the radiator support?
If not try LMC as they sell the stickers and might have a pic of one.
It will show you the routing of those pesky little lines.

TIMSPEED · 03-27-2003, 07:06 PM

Your kidding me right? On the truck there NEVER WAS a routing diagram. As far as LMC..they say "Emission Decal", which I HAVE, but that just says what I NEED, doesn't show how it goes...I guess maybe a test & repair station is what I'll need to go to.

Mike76251 · 03-27-2003, 07:19 PM

Sorry Man,
My 1972 Camaro had one and it showed where all the lines went.
Not with your '75 truck it appears.
Someone else will have to tackle this one.

apstguy · 03-27-2003, 08:34 PM

Sorry, I don't have an answer. I see you live in Modesto though. I don't live too far down the road. Ever need help drop me a line!

03-27-2003, 06:26 PM	#1
TIMSPEED Join Date: Jan 2003 Location: Modesto, CA Posts: 1,321	Dual Diaphragm EGR Valve Question... PLEAS HELP! Amazingly, in the 1975 model year, it was possible to get a C10 withOUT AIR tubes in the exhaust manifolds, but if you did, it meant you had to have a Dual Diaphragm EGR Valve. Now, since my dad was cool like that, and I have one of these lucky trucks, does anyone know how the dang thing hooks up? I'm pretty sure I've got the top tube hooked up right (to the TVS Switch on the thermostat housing) but as for the bottom..I have no idea...or where can I get a vacuum diagram? HEEEEELP! This is the only thing I need to get done for this truck to pass it's final smog inspection (it becomes smog EXEMPT after it does!) __________________ I have a few cars... See Them Here

03-27-2003, 07:06 PM	#3
TIMSPEED Join Date: Jan 2003 Location: Modesto, CA Posts: 1,321	Your kidding me right? On the truck there NEVER WAS a routing diagram. As far as LMC..they say "Emission Decal", which I HAVE, but that just says what I NEED, doesn't show how it goes...I guess maybe a test & repair station is what I'll need to go to. __________________ I have a few cars... See Them Here Last edited by TIMSPEED; 03-27-2003 at 07:09 PM.

03-27-2003, 08:34 PM	#5
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,087	Sorry, I don't have an answer. I see you live in Modesto though. I don't live too far down the road. Ever need help drop me a line! __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

03-27-2003, 06:53 PM	#2
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	Man, I feel for you living in California. I love the place but TOOOOOO many laws. I was raised in Long Beach so I know from where I speak. That was 30 years ago so maybe I don't (?) Anyway, off the soapbox....... Do you still have the emmisions sticker on the radiator support? If not try LMC as they sell the stickers and might have a pic of one. It will show you the routing of those pesky little lines.

03-27-2003, 07:19 PM	#4
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	Sorry Man, My 1972 Camaro had one and it showed where all the lines went. Not with your '75 truck it appears. Someone else will have to tackle this one.



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