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EGR? Can someone explain?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 85blaze, Feb 26, 2001.

  1. 85blaze

    85blaze 1/2 ton status

    Feb 20, 2000
    Likes Received:
    Corning NY
    I searched the posts and it seems like i have an EGR problem, but where exactly is the EGR valve and what does it do? and can i get rid of it? I have no other emmisions equip. left on the truck..... Thanks all

    Finally done after 8 months.. Not really.. IM never going to be done. Stroker motor is next
  2. Blue85

    Blue85 Troll Premium Member

    Jul 26, 2000
    Likes Received:
    Grand Rapids area
    If you have no other emissions devices on the truck, that in itself may be your problem. Everything is designed to work together. For every emissions device you pull, you are likely to have to mess with two other things to get it all running right again.

    The EGR valve is mounted on the passenger's side of the intake manifold. It is mounted towards the back, not too far from the distrubutor.

    Exhaust Gas Recirculation is the process of taking gases alread expelled from the cylinders and running it back into them. The goal is lower hydrocarbon emissions from unburned fuel. It is accomplished by passages in the manifold and heads. The valve is a vacuum diaphram driving a small pintle that blocks or opens the passage between the exhaust and the intake. Since the exhaust has back pressure and the intake has vacuum, providing this passage is all that is needed to drive some gasses in this fashion. It is common for the valve or the manifold passages to get clogged up with carbon, especially if you have been running rich or with a weak ignition component. To test it's operation, you can push up on the diaphragm when the engine is running but is not yet hot (be careful). The rpms should drop. If not, the passages are probably plugged. Pull the valve off and you should see. To test the valve itself, you would just need to apply vacuum.

    What kind of symptoms are you having?

    <font color=blue>"We have to take seriously the role in this problem of older men who prey on underage women..." Bill Clinton, 1996.</font color=blue>
  3. woodpecker

    woodpecker Registered Member

    Oct 19, 2000
    Likes Received:
    Mount Vernon, WA
    Your 85 doesn't have a computer, and so you should be able to disconnect your EGR without any "check engine" lights coming on. Of course most would say to get a new one as soon as $ permits b/c it's supposed to keep your rig running cleaner (emissions, etc), but has nothing to do with performance.

    The EGR is located (at least on my 86 305 CID) near the carburetor, just to the left (passenger side) and in the rear. It's made of metal, and is that weird golden/silver color? It's a diaphragm valve, so imagine something that could house a diaphragm and look for it. Once you find it, there is a small tube that comes out of the top of it, and connected should be a little rubber "elbow" going to some vaccuum line. What I did to disconnect mine was pull off the elbow, and stick some vaccuum line with a screw in it to plug it off. That cured my stumbling acceleration and rough idle.

    I'm a beginner so forgive the horrible descriptions, etc.


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