What makes these trucks destroy distributor caps/rotors?

Discussion in 'Engine Performance + Maintenance' started by redfishsc, Oct 7, 2018.

  1. Aarong23

    Aarong23 OBS Enthusiast

    Age:
    26
    Messages:
    52
    Likes Received:
    33
    Joined:
    Nov 25, 2011
    Location:
    Oklahoma
    Freaking tell me about it. Lol. Have has two obs trucks and both said the same thing when the distributor crapped out.
     
    redfishsc likes this.
  2. redfishsc

    redfishsc Apparently can't own too many Suburbans

    Messages:
    409
    Likes Received:
    122
    Joined:
    Nov 7, 2016
    Location:
    South Carolina
    Are the Delco 9718Q the right style? Thats the only Delco I see on Rockauto.com

    If so, I will order two sets since I have two of these trucks
     
  3. Schurkey

    Schurkey I'm Awesome

    Messages:
    194
    Likes Received:
    67
    Joined:
    Jan 14, 2018
    Location:
    The Seasonally Frozen Wastelands
    Ozone,moisture, crankcase gasses, nitric acid...would affect EVERY terminal in the cap, not just #5.

    The problem with #5 is probably not INSIDE the distributor cap, even if the damage is showing up there. The distributor cap is a symptom, not a cause.

    As I told him in another thread, I'd be looking at cranking compression, spark plug, and plug wire. Wouldn't surprise me to find that the plug wire has excess resistance, maybe even open-circuit. Fifteen minutes on an ignition oscilloscope would probably tell that tale (although five minutes with an ohmmeter might be just as effective, if not as interestingly.)


    RFA? Do you mean Radio Frequency Interference (RFI)?

    No amount of resistance will change the voltage delivered until current starts to flow. The carbon-rope plug wires use heavy resistance to reduce current flow. The helical-wound plug wires use inductance to reduce current flow. Both types reduce current flow. The big advantage of the wire-wound style seems to be that they have a longer service life compared to the carbon-rope kind--not that they actually work better.
     
  4. redfishsc

    redfishsc Apparently can't own too many Suburbans

    Messages:
    409
    Likes Received:
    122
    Joined:
    Nov 7, 2016
    Location:
    South Carolina
    Ok guys so I did several things this evening. The only thing that seemed to "fix" (or more properly, pacify) the problem was replacing the plug on #5.

    I pulled the distributor cap and didn't find much corrosion and the posts looked 100% solid (not burned/consumed) . I used some 400 grit to file what little bit of white oxidation was there.

    No change.

    I adjusted the cmp retard to 0.5(+). It wasn't far off but still out of spec (was +4.6).

    No change

    Swapped the plug (NGK) out of curiosity with a new one i had spare and viola...... No misfires. Drove it about 8 miles, didn't log (or feel) a single misfire.

    I always thought NGK was a good brand for Chevy but not in this truck.
     
  5. redfishsc

    redfishsc Apparently can't own too many Suburbans

    Messages:
    409
    Likes Received:
    122
    Joined:
    Nov 7, 2016
    Location:
    South Carolina
    By the way, I will be ordering new Delco plugs and wires, and also cleaning the distributor vents. Just didn't have time tonight for that.
     
  6. Schurkey

    Schurkey I'm Awesome

    Messages:
    194
    Likes Received:
    67
    Joined:
    Jan 14, 2018
    Location:
    The Seasonally Frozen Wastelands
    Nothing wrong with NGK, as long as you have the correct plug for the application.

    If it was a matter of "NGK is not compatible with this truck" the other seven cylinders would complain, too.

    There's something wrong with THAT spark plug. Inspect it carefully, figure out what happened.
    Fouled?
    Cracked insulator?
    Loose conductor inside the ceramic?
    Worn?
    Gapped wrong?
    Something else?

    I'd still test the plug wire and the cranking compression.
     
    redfishsc likes this.
  7. Gramps

    Gramps Newbie

    Messages:
    42
    Likes Received:
    18
    Joined:
    Aug 24, 2012

    Not only that but ac Delco plugs are reboxed from 3 other manufacturers. Ngk, champion, autolite depending on what plug it is. Iirc ngk makes all the ac iridium, and it’s a mix of the 3 for the copper and platinums.
     
    Schurkey likes this.
  8. 454cid

    454cid I'm Awesome

    Messages:
    1,034
    Likes Received:
    110
    Joined:
    Sep 5, 2010
    Location:
    The 26th State
    I didn't know about Champion and Autolite. I thought NGK make most of them. I have some regular NGKs but they're still sitting in the boxes.
     
  9. redfishsc

    redfishsc Apparently can't own too many Suburbans

    Messages:
    409
    Likes Received:
    122
    Joined:
    Nov 7, 2016
    Location:
    South Carolina
    So do i want to order the 9718Q or the 718Q plug wires? Both are Delco, the 718Q is more expensive but that really doesn't mean anything.
     
  10. 98 Nitro

    98 Nitro OBS Enthusiast

    Messages:
    82
    Likes Received:
    13
    Joined:
    Apr 10, 2017
    Location:
    Indiana
    The one with 9 is the cheaper made in China version. Last year I bought the Delphi set XS10241 on Amazon , it's in between in price but was US made i believe and I've had no problems.
     
    redfishsc likes this.

Share This Page