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Thread: 1986 K5 Blazer

  1. #1
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    1986 K5 Blazer

    Hey guys, brand new to this forum. I've had my truck for two years. I love it. And I'm trying to make it "beefy" without taking it too far, as I need it to be a daily driver for me.

    So...I was wondering, I have these problems. What do you guys think is the best course of action, places to buy parts etc etc.


    I need cap and wires, plugs, leaks a little oil form the pan (no biggie, need a new plug) I need wheel bearings, maybe hubs, radiator hoses, my rear axle makes a clunk and I just blew out the pinion seal and replaced it. it still clunks i don't know if it's the axle or if it's the U-joints. it only "clunks" in neutral when I'm at about 35-45 MPH. It needs ALL NEW bushings, ball joints, tie rods, and timing adjusted...I also have a dead miss in one of my cylinders (says my auto teacher).
    Last edited by 86K5BLAZER; 11-28-2010 at 10:57 PM.

  2. #2
    Senior Member Oldmech's Avatar
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    clunks? as in clunkclunkclunkclunkclunk as it is coasting or it clunks once when it goes into gear?
    On a level surface, block the tires and put it in neutral, then grab the driveshaft and see if you have any play in the u joint.
    The miss could be a lot of things at this point.. if it is a dead miss, you should be able to tell which cyl when you pull the plugs,, one of them is going to be wet. doing a tune up might fix it if you have a bad wire/plug etc... but by the same token, you might just want to do a compression test on it before you spend the money on the tune up and see if you have a bad cylinder...
    Most of the parts you mention can be had at a local parts store, O'rielys, auto zone etc...

  3. #3
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    It clunks exactly like "clunkclunkclunk" and shakes the truck when it's coasting only, but when I'm on the gas it's fine. If the truck was running for about a minute would I be able to tell by removing the plugs? or do I need to run it longer and let it cool off?

  4. #4
    Senior Member Oldmech's Avatar
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    A dead miss, means one of the cylinders is not firing at all. When a plug fires, the heat/explosion burns everything in the cylinder, fuel and oil... when a plug cant fire, there is most likely still fuel present, and oil, either small amounts that always get past rings, or bits of oil from the valves themselves.. it will accumulate on the plug, and should make whichever plug that is not firing look wet and fouled.
    If you are going to pull the plugs, beg borrow or steel a compression tester. Pull out all eight plugs.. hook the tester to one cyl at a time and roll the engine over, allowing the compression in that cyl to "hit" three times. then stop cranking and take your reading.. the gauge should hold pressure until you press the valve to release it. Each time the cyl hits the comression stroke, you should see it and feel it in the gauge/hose.. so it is something you can do by yourself in the garage. The gauge will tell you very fast if you have mechanical or electrical issues.

    the clunking is hopefully the u joint. the test i mentioned will tell you.. if the joints are not junk.. then the problem is in the rear differential.. and thats not cool....

  5. #5
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    Thanks man, I'm going to get a compression test done. As for the U-joint I hope that's the problem when I replaced my pinion seal I noticed my pinion nut was backed off...it was finger tight. I torqued it back down hard, with some loctite too, but not too hard to crush the sleeve further. The other U-joint towards the back of the trans is original, so I'm hoping that's it.

  6. #6
    Senior Member Oldmech's Avatar
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    I torqued it back down hard, with some loctite too, but not too hard to crush the sleeve further.
    Thats not a good sign... that nut along with the crush sleeve is what determines the depth that the pinion gears mesh with the ring gear...

  7. #7
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    I've driven it almost 400 miles since...I think I might spring for a new rear axle if it's not the U-joint. It's my daily driver so It's gotta be on the road. lol. I've had my eye on a M1009 Military Blazer 12 Bolt Rear. If I get a new rear end what route should I take?

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