318 Poly Vibration

Discussion in 'Mopar Performance Issues' started by matthon, Oct 25, 2018.

  1. matthon

    matthon Well-Known Member

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    Replaced motor with another 318 with low miles. New MSD and everything else except carb, used battery, alternator, and could not find a new trans mount. I painted engine, had valve covers and pan off, extremely clean.

    Ran really good, but had a slight hesitation above 50 so I rebuilt the carb.

    With a few adjustments it was running great and driven daily.

    Alternator went, replaced, charged battery, drove fine for many hours on a parts run, left it idling for 30 minutes or so. Got home, shut it off, battery spent.

    Next day replaced battery, drove to gas station, halfway there wouldn't move, wanted to stall, felt a vibration. Made it, needed gas to get back. Ran better by the time I got home. Checked all plugs, pulled wires apart, re-crimped a few to be sure. Checked firing order, started, ran the same, realized I forgot to plug 1 wire in, ran the same.

    Starts right up, idles nice, but has a vibration, not water pump, disconnected alternator, not alt, not power steering, no knocking noise, no oil in radiator, no metal in oil, pulled valve covers, all pushrods in place, checked lash but not by the book, just to see if one was way off. Used long screwdriver to ear trick all over engine, nothing detected. Put phone under car, in and out of reverse and drive, trans doesn't budge, mount doesn't move, engine moves a little, rubber mounts new, look fine, bolts tight.

    Today I checked the oil, a little bit of milky, been sitting over a month, ran it, looks fine. Water comes out the tailpipe at startup, seems excessive, but not green, not sure if it would be, no sweet smell, exhaust looks white-ish but it's cold right now. TTI headers/exhaust if it matters. Water comes out since I put this all together in mid July, but radiator has been the same level since.

    Vibration can be felt best on tops of fenders in front, and really well on top of air cleaner.

    Any input is appreciated.

    20180802_192506.jpg
     
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    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Distributor
       
    • 67Dart273

      67Dart273 Well-Known Member

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      Start by doing this: Devise a way to short the spark on individual plugs. Some guys pull off plug wires, DO NOT do that, as an "open" plug wire can cause cross-fire to adjacent "holes."

      Sometimes you can ground a clip / alligator lead to a small screwdriver. "Loosen" all the wires at the distro so they are just sitting in the towers. Use insulated fuse pullers to pull out a wire with one hand and slide your grounding probe in with the other.

      Use a tach if at all possible and listen. One cylinder that does not "drop" the same as the others indicates a "dead" hole for whatever reason.

      Compression test? Cylinder leak down?

      Somebody mentioned distributor. I've seen distributors worn in such a way that the points would sort of "accidently" open on some cylinders and not others, as the shaft was that badly worn/ bent. The oppposite can be true, sometimes they won't CLOSE on some holes
       
    • matthon

      matthon Well-Known Member

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      Thank you, I had heard of leak down but never did it, I'll look into that and comp.

      Distributor is new MSD from day one.
       
    • teringer

      teringer ase master hall of fame

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      could there be a crankshaft to converter mismatch?
       
    • matthon

      matthon Well-Known Member

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      I was thinking bad converter, or bad balancer.
      Maybe pull the pan and if everything ok change filter/fluid.
      Balancer might have slipped, I believe it has the rubber insert, have to check, but with no timing mark I won't be able to tell. I googled 318 poly balancer and some don't have a mark, saw a pic where one had a single 0 but I can't locate anything on mine.

      Crank to converter mismatch- I checked both engines over, only differences were the oil pan, pick up, and one valve cover, original was a 64, replacement is a 66. Would a mismatch be fine for 2 months?
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      I still say it again check the distributor. Doesn't matter if it's new or not do as 67darts273 said for starters.
       
    • Dicer

      Dicer Well-Known Member

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      You can use, what I use is an everyday run of the mill test light to short the cylinders one at a time. Just attach the clamp on anything that is a ground. The pointed probe will slide in the spark plug boot very easy, and you will not get shocked.

      test light.jpg
       
    • matthon

      matthon Well-Known Member

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      I will definitely check distributor to see if I can locate a dead cylinder.

      Not sure if the pick up would cause this, or the distributor itself.

      Just getting ideas, at work right now.
       
    • matthon

      matthon Well-Known Member

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      Drove home, ran worse, checked oil, definitely water in oil, dipstick covered in milk, wiped, put in again, straight up water on it, breather full of milk.
      Radiator still free of any oil, clear and clean.
      Had to go back out, couldn't go any farther.
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Sorry I missed the milky oil part earlier.

      Cracked head?
       
    • matthon

      matthon Well-Known Member

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      There probably isn't a rule book for water in oil but no oil in water, but I was thinking start by pulling the intake and hoping it's the guilty party. Then a compression test/leak down which would hopefully indicate if I need to go further.
       
    • matthon

      matthon Well-Known Member

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      Drained some oil into a glass jar, don't see water.
      Started grounding each cylinder and there was no change. Recalled in my first post when I mentioned I had left a wire off in error, plugged it back in, no change.
      Went to change cap for the heck of it, sent wrong replacement cap, cleaned up one on car, started, thought it was same or slightly better.
      Started grounding on other side, no change, pulled wire apart w/o noticing. Went to put back together, thought this wire looks pretty dam cheap!
      Wire on left extra from another set, strands packed, wire on right on car now, strand spread out under some back covering, destroyed on end. Rubbed my fingers on it and the strands were visible.
      Think this could be the cause?

      20181028_185807.jpg
       
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