Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Coil is over heating, and dying!???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Aug 1, 2002.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Okay... for all that have seen my previous posts, the saga continues! For those that have not, here is the condensed version:

    1. TWO Ferd fans installed to cure cooling issues, draw = 60A! One reversed, the other not (one pushes, other pulls)
    2. truck misteriously (sp?) dies in parking lot RE: coil failure
    3. coil is replaced
    4. truck runs fine for one day
    5. noticed volt meter in dash is reading VERY low @ idle
    6. next day truck misteriously (sp?) dies in DIFFERENT parking lot RE: over heating coil
    7. figuring that the VERY low voltage may have something to do with this coil prob, I had a 185A built.
    8. installed the new 185A ALT in truck, and drove it home from last lot where it died. Coil had cooled, and fired up again (voltage meter reads right at 12.6-13.0v now @ idle)
    9. got home to see if I could reproduce the "coil issues" with the new ALT
    10. sure enuf after about 30 minutes of running (starting, running, shutting off, cooling (fans run off constant power and a thermo switch), & starting again a few times) the coil shuts down again RE: overheating.
    11. left the rig in the driveway to cool over night.
    12. b4 work today, tried to start her up again - np go RE: coil failure.
    13. TIRED of buying new coils every other day! What to do?

    There! SO - let me start by saying that I have no ballast resistor since the original instructions said that I didn't need one. Can it hurt to install one anyways? Do I only have to put it inline with the coil's + wire?

    What else can cause a coil to over heat? It had this issue before and after the ALT, so that isn't the prob. It DIDN'T do it before the fans... so maybe it has something with too much voltage/amperage flowing from the ALT causing it to fry? I've been searching for info online about coils over heating, but I haven't found anything interesting yet... Ideas?

    Thanks all! /forums/images/icons/grin.gif

    -Dan
     
  2. BorregoK5

    BorregoK5 1/2 ton status

    Joined:
    Sep 7, 2001
    Posts:
    2,457
    Likes Received:
    0
    Location:
    San Marcos, Ca USA
    Hey Dan, I've worked with coils on a smaller scale for years and come accross this problem before. With the capacitor, the current provided by the collapsing field will discharge through it, limiting the voltage, and the current/field will collapse very rapidly, having a discharge path to ground through the capacitor. A poor ground is usually the suspect but here are a few other items that could be different in your system. If your running an aftermarket ignition like MSD then the balast is not needed, otherwise it is. A non-ballast coil is designed to produce full spark output with 12 volts on the input . A ballast coil is designed to produce the same spark output, but with only 6 to 9 volts on the input. Prolonged running of a ballast coil without one could overheat the coil. Switching from a balast to non balast coil would also allow a wider plug gap but shouldn't cause overheating of the coil if it wasnt performed. Without the capacitor, the voltage will rise to a very high value at the points, and arcing will occur. The time for the field to collapse will also increase. Hope this helps.
     
  3. BorregoK5

    BorregoK5 1/2 ton status

    Joined:
    Sep 7, 2001
    Posts:
    2,457
    Likes Received:
    0
    Location:
    San Marcos, Ca USA
    A bad ground could have damaged your ignition module, might be the cause but they usually just die.
     
  4. ntaj*ep

    ntaj*ep 1/2 ton status

    Joined:
    Feb 4, 2002
    Posts:
    3,248
    Likes Received:
    1
    Location:
    Evergreen state
    Your fans are pulling 60 ampers. Wow, you running a relay with that curcuit? What company is your coil/dist.? Where are you pulling power for the fans? I think your onto something with the fan/coil corrilation.
     
  5. TopOff

    TopOff 1/2 ton status

    Joined:
    Jan 16, 2002
    Posts:
    1,760
    Likes Received:
    0
    Location:
    Folsom, ca
    What ignition system are you using?
     
  6. dleroy43

    dleroy43 1/2 ton status GMOTM Winner

    Joined:
    Jul 22, 2002
    Posts:
    1,517
    Likes Received:
    0
    Location:
    Martinsburg WV
    How would you know if your coil is overheating? My truck sometimes takes a nap
    when I turn it off. Then I wait 10min to 1 hr before it trys to crank. /forums/images/icons/confused.gif
     
  7. shane74

    shane74 1/2 ton status

    Joined:
    Feb 12, 2002
    Posts:
    4,100
    Likes Received:
    0
    Location:
    Vancouver, WA
    When my IM went bad it did exactly what is being described here. I too replaced everything else. Coulda saved myself a big chunk o' change if I would have replaced it first! /forums/images/icons/tongue.gif
     
  8. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Mike- The module is good. I run a Mallory Unilite distibutor, and the module tested good.

    Aaron- YEA, 60A total! Each fan has its own 30A breaker fed right from the batt. with 8ga. wire. Then thru a relay triggered by a thermal switch.

    Nick- IGN wise, I'm using a Mallory Unilite dist. with a MSD offroad coil (no int. resistor). Now that that is fried, I'm gonna try a resistor type coil tonight. $26 @ Napa!

    dleroy43- I know its over heating since I can't touch it, even with my Mechanix gloves on! /forums/images/icons/wink.gif

    Shane- The only reason I've been thru the module and the ALT is because the fans pull 60A, and the stock ALT only delivers 63A max., and the module DID die on my earlier when I ran the batt dead. Unilite IGN modules die when you run the batt to 0v, unless protected with a special gadget they sell seperatly. /forums/images/icons/tongue.gif I try my damndest not to throw money at the truck without KNOWING what is wrong first! /forums/images/icons/laugh.gif

    Everyone- Think installing a coil w/a internal resistor is worth a shot for $26? Thanks! /forums/images/icons/smile.gif

    -Dan
     
  9. shane74

    shane74 1/2 ton status

    Joined:
    Feb 12, 2002
    Posts:
    4,100
    Likes Received:
    0
    Location:
    Vancouver, WA
    I was just speaking for myself. You had a need for the upgrade regardless. I was just sterpid! /forums/images/icons/crazy.gif /forums/images/icons/blush.gif /forums/images/icons/grin.gif
     
  10. ntaj*ep

    ntaj*ep 1/2 ton status

    Joined:
    Feb 4, 2002
    Posts:
    3,248
    Likes Received:
    1
    Location:
    Evergreen state
    Ok, other than my personal prefrence, unilight dist. are the devil. That out of the way, I currently run a Mallory magnitic breakerless dist. and promaster coil pack. I've run Mallory stuff for some time and even though the instructions say DO NOT use a ballast you need to. And it needs to be a Mallory ballist or it still will do damage. I don't totally know why that is but it works. The issue that throws me is why did it start happening when the fans were installed? Maybe its just coincedence. I've seen the uni light module do some very strange stuff before. I think you should test that first. If you have a multimeter, call 702 882 6600 for Mallory tech. line. If you didn't know the # already. See if they can help /forums/images/icons/smile.gif & may the force be with you. /forums/images/icons/grin.gif

    Know what I didn't read your last post all the way through.....bad bad. Sorry dude I'm stumped. If grounds are all ok and your getting the voltages you need...........My opinion (once again not needed) Unilight= prince of darkness. /forums/images/icons/tongue.gif
     
  11. Philly87

    Philly87 1/2 ton status

    Joined:
    Jul 14, 2000
    Posts:
    465
    Likes Received:
    6
    Location:
    El Paso, TX
    Are you running a ballast resistor on the unilite?
     
  12. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Aaron- well I tried a regular ballast last night - a 2ohm ceramic jobber. It dropped the coil's voltage from 11.4v down to 6.5v, and the coil would HARDLY fire at all. Only enuf for a little chug here and there when cranking. So that sure isn't going to work. Do you happen to know what the rating is on the Mallory ballast resistor is?

    I've got the protection module inline with the IGN module, and it has successfully protected it thru lotza stuff that would have killed it before I installed it!

    And check this out... when the fans run after the IGN is off, the coil recieves .3-.4v until they are turned off. What would this indicate? I'm going to test a hunch by moving the connection that powers the switch in the cab to be powered directly from the batt., vs. the fuse box where it is now. Just to see if that has anything to do with it... /forums/images/icons/tongue.gif

    Any other ideas?

    -Dan
     
  13. 76chevy

    76chevy 1/2 ton status

    Joined:
    Aug 16, 2000
    Posts:
    246
    Likes Received:
    0
    Location:
    Utah
    You said the fans still receive power when you switch the ignition off. It sounds like the power is splitting off the wire that feeds your ignition and you are getting the extra energy from your igintion unit.

    Where are you pulling your power from? I was going to recommend pulling your power from another ignition switch source but it looks like you are going to try that.

    The MSD and other igitions keep a little bit of power in them after you turn the ignition off. You may be getting the running fans from the left over current. That may be what is killing your coil.

    If using another switched power source doesn't work out, I would check the diode that should be or is installed on the altenator to kill the extra energy running through the lines.

    Good luck. Let us know.
     
  14. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Where do I start with this one... /forums/images/icons/wink.gif The power for this entire setup is on constant power. The breakers and relays are fed DIRECTLY from the battery, while the switch in the cab gets its constant source from the fuse block. So no esay out "power drain off thing" happening here. I have seen what you are talking about though. The fan can act like a ALT as it spins down, feeding current back thru the system. But in my case, the truck does actually shut off when told to do so! /forums/images/icons/smile.gif

    And the ALT is a brand new custom made 185A ALT. Plus the problem existed before it was replaced. /forums/images/icons/frown.gif

    -Dan
     
  15. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,092
    Likes Received:
    492
    Location:
    Grand Rapids area
    How are you measuring your voltages? The power to the coil is switched, so you should be using an oscilloscope. With a DMM, you will get an average or something...
     
  16. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    I'm using a DMM... don't have a oscilloscope. /forums/images/icons/tongue.gif

    -Dan
     
  17. BurbinOR

    BurbinOR 3/4 ton status

    Joined:
    Feb 17, 2000
    Posts:
    5,829
    Likes Received:
    0
    Location:
    Oregon
    Didn't read the whole thread, sorry, but can you put your stock HEI back in? If so, do it..........and never worry again. /forums/images/icons/tongue.gif
     
  18. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    HEI = YUCK! I'll try to get this Mallory/Accel combo working prior to ditching $300+ worth of ignition equipment! /forums/images/icons/tongue.gif Not that I don't have faith in HEI - I have had quite a few HEI systems treat me very well, but I don't want to SPEND $$$ to go stock! /forums/images/icons/tongue.gif

    -Dan
     
  19. 76chevy

    76chevy 1/2 ton status

    Joined:
    Aug 16, 2000
    Posts:
    246
    Likes Received:
    0
    Location:
    Utah
    Are you 100 percent positive it is related to your fans?

    What if you put the stock fan back on for a test. Disconnecting the fans would help you see for sure if it is the fans.

    It sounds like you need to go back to the begining.You have tried a lot of things and it seems like you have an idea of what you are doing so I would switch back to stock and see if it still happens, if not, go from there.Of course that is easier said than done. /forums/images/icons/smile.gif I know how frustrating these things can be.We are all pulling for you.
     

Share This Page