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  1. #1

    Default Misfiring troubleshooting, 86 k10 4x4 silverado 305

    Alright, I have a 1986 4x4 silverado with a 305. Lately I've been having problems with two cylinders not firing.

    I've narrowed it down to a few problems, I believe it's either a blown head gasket or bad plug wires.
    I'm just looking for some additional opinions on what the problem could possibly be.

    Symptoms: Like I said, two cylinders aren't firing, it's the closest two on the right side, standing in front of and facing the truck. I believe those are 1 and 3? A chevrolet guide I have says that two adjacent misfiring cylinders usually result from a blown head gasket, which would explain a thin lair of white foam in my coolant right?

    However, upon inspecting the plug wires, I noticed that they are in pretty bad shape. I have a small oil leak that drips on them occasionally causing them to swell and I noticed one was split. It was a rough inspection so there's a good chance the rest are damaged as well.The split wire was the cylinder after the further misfiring one, however. The two plugs in those cylinders are fouling, and look similar to a oil foul, but I might be wrong. After unplugging those two wires, it still misses, but that could still be due to either problems, right?

  2. #2
    Master Mechanic TahoeFever's Avatar
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    Quote Originally Posted by Daniel View Post
    Alright, I have a 1986 4x4 silverado with a 305. Lately I've been having problems with two cylinders not firing.

    I've narrowed it down to a few problems, I believe it's either a blown head gasket or bad plug wires.
    I'm just looking for some additional opinions on what the problem could possibly be.

    Symptoms: Like I said, two cylinders aren't firing, it's the closest two on the right side, standing in front of and facing the truck. I believe those are 1 and 3? A chevrolet guide I have says that two adjacent misfiring cylinders usually result from a blown head gasket, which would explain a thin lair of white foam in my coolant right?

    However, upon inspecting the plug wires, I noticed that they are in pretty bad shape. I have a small oil leak that drips on them occasionally causing them to swell and I noticed one was split. It was a rough inspection so there's a good chance the rest are damaged as well.The split wire was the cylinder after the further misfiring one, however. The two plugs in those cylinders are fouling, and look similar to a oil foul, but I might be wrong. After unplugging those two wires, it still misses, but that could still be due to either problems, right?
    sounds good to me ..those are the things i woulda checked
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  3. #3
    Jr. Apprentice bkovacs's Avatar
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    I used to have the same motor in my Blazer, it actually never gave me a single problem
    anyways I would say if there is foam in your oil its deff. a sign that head gaskets are leaking.. just make sure you replace both instead of just one!
    '99 K2500 Suburban Vortec 7400
    '00 k2500 Silverado Vortec 6000 ex. cab

    '84 K5 Blazer 4x4 lifted (defunct)
    '86 Dodge w250 4x4 lifted (also defunct)

  4. #4
    Jr. Apprentice bkovacs's Avatar
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    actually I take that back if those two cylinders are missing and there is foam in your oil it could be even more serious, check your heads or block for cracks
    '99 K2500 Suburban Vortec 7400
    '00 k2500 Silverado Vortec 6000 ex. cab

    '84 K5 Blazer 4x4 lifted (defunct)
    '86 Dodge w250 4x4 lifted (also defunct)

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