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Thread: Misfire in #7

  1. #1

    Default Misfire in #7

    ive replaced the plugs, wires, cap and rotor

    compression test reveals 90 psi when others are around 140

    i do burn oil and ive replaced my plenum so its not that leaking

    my guess is valve seals, any input would be appreciated!

  2. #2

    9t9-5.2's Avatar
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    Pressurizing the cylinder would tell you if the head gasket, valves, or rings are the problem. May have valve seal issue also.

    "Excuse me if I have some place in my mind, where I go time to time"

  3. #3
    niebs's Avatar
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    Valve seals wont lose compression.

    Do a leak down test to find where the compression leak is. Rings/cylinder walls could cause burning oil and compression lost.

  4. #4

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    If you're burning oil, you have a ring problem. Squirt some oil into that cylinder and see if your compression goes up. The oil will act as a temporary seal. If it does go up and then down, it is more likely to be a ring. If it stays the same, more likely to be a valve.
    Your major telltale is the blue smoke coming out of your exhaust. Remove the spark plug from no 7 to make it dead. Run the engine and see if you are still smoking. If not, there is the possible culprit.

  5. #5

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    Thanks for the information guys.

    So if it’s a ring is it worth fixing?
    I’d probably have to take it to a machine shop right?

  6. #6
    niebs's Avatar
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    Quote Originally Posted by david_carls_jr View Post
    Thanks for the information guys.

    So if it’s a ring is it worth fixing?
    I’d probably have to take it to a machine shop right?
    Really depends how bad it is and your skill level at turning wrenches. And how invested you are in the truck.

  7. #7

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    Quote Originally Posted by niebs View Post
    Really depends how bad it is and your skill level at turning wrenches. And how invested you are in the truck.
    I haven’t put tons of modifications in as investments but I have thrown a lot of parts at it.
    I have people that help me do the the work, I just don’t have the luxury of time since it’s my daily driver

  8. #8

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    Quote Originally Posted by david_carls_jr View Post
    I haven’t put tons of modifications in as investments but I have thrown a lot of parts at it.
    I have people that help me do the the work, I just don’t have the luxury of time since it’s my daily driver
    It may be cheaper or at least a similar cost to have another junk yard 360 installed and put whatever parts you have on the original on the replacement. It'll probably be faster as well. An engine swap is less than a 3hr job for a good shop with a couple guys working on it.. May be able to fix it for less than 1K. You would only need to rent a car for a short period of time. A friend of mine who used to own an engine replacement shop, could take out a small block anything in less than 20 minutes.
    I have heard of guys doing a re-ring in chassis. It depends on what is in the way and if you have a lift available. You can at least ask around if you need someone else to do it because of time constraints.

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