Strange rattle at front of the engine

Discussion in 'Street/strip 400/430/455' started by Jim Blackwood, Jul 17, 2021.

  1. Jim Blackwood

    Jim Blackwood Well-Known Member

    Put the dial back light on it yesterday. I don't have a real good shot at the zero mark due to the location of the crank position sensor but it looked really close to about 60 degrees of advance at 1200 rpm, the one point where I checked it. So I think that's the problem. That naturally raises the question of why. The immediate suspect is the Megajolt controller. More testing is needed obviously.

    Jim
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    On an MSD, if you reverse the polarity on the magnetic pick up, it will run VERY advanced. Could that be your problem?
     
  3. Jim Blackwood

    Jim Blackwood Well-Known Member

    Wouldn't think so, but I'm looking for anything that might have been changed so that goes on the list.

    Jim
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Reverse the wires at the pick up, and see if the problem goes away.
     
  5. Jim Blackwood

    Jim Blackwood Well-Known Member

    Good suggestion but I wonder what are the chances of it running normally for six years or more before this suddenly cropped up?
    I'll do it, it means disassembling the Ford plug that goes into the sensor which is likely to be a pita. Twice. But I can do it and thank you for the suggestion. I also have a 3rd EDIS8 module that I will plug in and test with that. Odds of having the exact same failure in two different modules seem extraordinarily high but maybe no more than the above. Seems like it's either that or wiring. EDIS uses a sawtooth wave to send advance info to the module from the megajolt and maximum advance is 60 degrees which coincidentally enough is what I'm seeing so far. But in the absence of a connection on that wire (Ford provided a removable plug to test this) the module reverts to 10 degrees advance in limp mode. So that would seem to indicate that in order to tell the module to go to full advance that line would have to go high and stay there maybe? As in shorted to 12vdc and how often does that happen in a wiring harness? Again, extraordinary high odds. That seems to be what I'm dealing with. And the plug is a very short distance from the module. *Complaint*: Why is it I seem to get all of the really weird problems?

    Jim
     
  6. Jim Blackwood

    Jim Blackwood Well-Known Member

    More info. So after unbolting the ac compressor and moving it out of the way, cleaning and inspecting the connectors and wires, recharging the battery, unplugging the SAW test plug, swapping in another module and hooking up the dial back timing light I fired it up and it showed 8 degrees of advance. But the rattle was still there. Curses! Also plugging in the test light immediately sent it to 60 degrees and it stayed there while increasing engine speed. Double Curses!

    Next step, I'll put a drill on the oil pump to try and eliminate that from the possible causes. All belts are removed. I will also try it with the transmission in gear. Perhaps with the clutch pushed in also.

    Jim
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Yeah, if it was running OK, the wires don't reverse themselves. Does Megajolt have a tech line?
     
  8. Jim Blackwood

    Jim Blackwood Well-Known Member

    Maybe? The rattle seems like the first thing though. To eliminate the oil pump (we had reshimmed it) I used a drill to run it, no rattle. Started the engine with the drill running the oil pump, rattle comes back. I think that just leaves internal parts and the timing chain comes next. Play was 7 degrees at the crank. Spark knock could hardly be a problem at 8 degrees advance right?

    With the advance plug pulled out the edis defaults to 10 degrees. I measure 8 at the crank with the timing light. It rattles whether the plug is in or out. The rattle is actually worse at 8 degrees than it is at 60 oddly enough, I don't really get that. And it does seem to be getting worse. I think I'm going to have to pull the timing cover.

    Jim
     
  9. 73 Stage-1

    73 Stage-1 Dave

    You mentioned it is a stick. Are you sure the noise is coming from the front? Could easily be a throwout bearing... did you try it with your foot on the clutch?
     
    qak likes this.
  10. Jim Blackwood

    Jim Blackwood Well-Known Member

    Just did. Put a stick holding the clutch in. 5th gear, brake set. No change. Sounds like a danged diesel.

    Jim
     
  11. Matt Knutson

    Matt Knutson Well-Known Member

    Rod knock? Piston slap?
     
  12. nick tomlinson

    nick tomlinson Well-Known Member

    Defenitly check the crank pulley bolts. had noise that sounded like a bad waterpump and found crank pulley bolts lose. The pulley was cracked all the way around the center!
     
  13. TORQUED455

    TORQUED455 Well-Known Member

  14. Jim Blackwood

    Jim Blackwood Well-Known Member

    I'll try to shoot a video later today or tomorrow. Definitely not loose pulley bolts or damper. All belts removed. Doesn't sound like a bearing knock and oil pressure is good.
     
  15. Matt Knutson

    Matt Knutson Well-Known Member

    Collapsed lifter? Have you inspected the valve train?
     
  16. Stevem

    Stevem Well-Known Member

    I have not looked thru all the post on this so let me ask, have you tried pulling the plug wire off both front cylinders on each bank one at a time?
     
    Max Damage and TrunkMonkey like this.
  17. Jim Blackwood

    Jim Blackwood Well-Known Member

    Not yet but those are good ideas. I hope to do some more checks tomorrow.

    Jim
     
  18. Schurkey

    Schurkey Silver Level contributor

    I thought incorrect, reversed-polarity resulted in RETARDED timing; you'd know if the polarity is correct by setting it up for the most-advanced timing.

    Am I wrong?
     
  19. GS Dude

    GS Dude Active Member

    Check your crank pulley bolt, might be coming loose.
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Years ago, I used a Stinger distributor which used a Chrysler pick up to trigger an MSD box. When I got the polarity wrong it ran way advanced. With an MSD pickup, the wires from the pickup are black/violet and black/orange, the wires on the MSD box end are green and violet. To get the polarity right, never connect violet to violet. So the black/orange goes to violet on the box end.
     

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