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Half a crank when hot...

Discussion in 'Early CJ5 and CJ6 Tech' started by double R, Jun 22, 2011.

  1. Jun 22, 2011
    double R

    double R Member

    Reseda, CA
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    Mar 18, 2003
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    I've been having problems with starting when the engine is hot. It happened again just now, I make a quick stop at a store, maybe 5-10 minutes, I hop in and try to start it several times and I get half a crank each time. The mechanic nearby used of those portable jump starters and it worked. He thinks my timing is off. Motor is tbi 4.3 chevy.

    The other times I've had this happen, it would usually start after I let it sit for about 15+ minutes.

    Starts ok when cold and even after sitting for 2 weeks; cranks perfectly. Happens when the engine is warm and I shut the engine down briefly.

    Battery is new and I got one that has a higher cranking amps than what's recommended. I re-did one of the butt splice at the solenoid wire to fusible link thinking that the connection there wasn't good but that didn't help. I rebuilt the starter about year ago. Any ideas?

    I'm most worried when making a left at intersections, I know if I stall, I wont be able to start it. I've had to wait several minutes at a gas station once before it would crank continuously and start.
     
    Last edited: Jun 22, 2011
  2. Jun 22, 2011
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Sounds like starter is getting heat soaked, or it's possible the timing is off. Check connections first, grounds, power, etc. and check timing first. If all ok I'd seriously suspect the starter. Common on GM's.
     
  3. Jun 22, 2011
    LarryD

    LarryD Member

    Gallup NM/ 4 Corners
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    They say hot weather is harder on the starting circut than cold. In my expierence what you have described souns like a starter. Most chain parts stores will check the starter for free.
     
  4. Jun 22, 2011
    cj5lover

    cj5lover Member

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    some kind of vapor lock due to the heat?? i agree, try a new starter. i know with all my old cars i've had, in the summer, i'll have an electric fan going for 5mins when i stop anywhere to cool things down.
     
  5. Jun 22, 2011
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Vapor lock will cause no/hard starts when hot but not a no crank situation. Vapor lock is a fuel issue
     
  6. Jun 22, 2011
    double R

    double R Member

    Reseda, CA
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    Thanks for the replies...Not sure if my description of "half a crank" made any sense but glad you guys understood. Basically, the starter engages and just cranks for a second and then stops as if there's not enough power to continue cranking.

    I thought I had the timing set correctly but will check again. I don't have a timing light right now so I might just pull the starter and have it checked. In the case that I have to replace the starter, do I need some kind of shield for the heat? Are the autozone starters any good?
     
  7. Jun 22, 2011
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    Your solenoid could be the cause. It will cease to operate on low current (high resistance) due heat. If it was mine, I would run another wire (10 ga) from the ignition switch "start" terminal down to the solenoid and leave the original wire. This increase in wire size will give the solenoid the amount of current it needs to stay latched during cranking.
     
  8. Jun 23, 2011
    colojeepguy

    colojeepguy Colorado Springs 2019 Sponsor

    At the foot of...
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    No.
    All the big chains (PepOreillyAdvanceZone) have crap electrical rebuilds.
    Your whole issue may be a bad starter and/or solenoid.
    Also, a starter heat shield may help-depending on how your exhaust is routed, you may be cooking the starter.
    If it continues to be an issue, you might look into wiring in a Ford starter solenoid that mounts on the fender.
     
  9. Jun 23, 2011
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Regarding the timing theory, that's easy to test. When it's hot and you have this problem, remove the coil wire and see if it cranks easily. Without ignition, the timing will have no effect.
     
  10. Jun 23, 2011
    aallison

    aallison 74 cj6, 76 cj5. Has anyone seen my screwdriver?

    Green Cove...
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    Another vote for starter..........
     
  11. Jun 23, 2011
    mb82

    mb82 I feel great!

    Charlottesville Va
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    If you replaced the battery connection, did you also replace all the wiring that goes from the battery to the starter? You can get corrosion in there and it would give a similar problem.
     
  12. Jun 23, 2011
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    My father-in-law had a chevy based Winnebago that had that problem. When he got tired of jump starting it when hot, he put a heat shield of some kind around it. Just need something like a metal sheet between the starter and the exhaust manifold/downtube/header on that side.
     
  13. Jun 23, 2011
    sailorjeeper

    sailorjeeper What... me worry?

    Spiro, OK
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    Don't forget to look at the other side of the circuit also. Once I had a similar problem and found that a PO had used steel washers to shim the ground cable, this was fine when cold but when hot the corrosion proved to be an excellent insulator.
     
  14. Jun 24, 2011
    double R

    double R Member

    Reseda, CA
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    I'll be checking the connections next...

    Finally have the chance to start looking into this...day off today.

    I did the test that Tim suggested. I drove around for a bit. Once I got the weak crank problem to appear, I disconnected the coil wire and cranked...surprisingly, it cranked fine. Drove around and tried the test again and I got the weak crank this time around even with the coil wire disconnected. Tried one last time and still got the weak crank with coil wire disconnected...

    Letting it cool. Will check wiring next.
     
  15. Jun 25, 2011
    Shadow

    Shadow Member

    Tallahassee,Florida
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    I had a Chevy P/U with headers that did the same thing. I tried the fancy starter insulation, and also made a heat shield which all failed. I bought a solenoid relocation kit from Jegs and cured the problem. The instalation is easy and the instructions were great.
     
  16. Jun 25, 2011
    double R

    double R Member

    Reseda, CA
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    I got the starter tested and it's still good.

    Seems to narrow it down to heat (exhaust manifold is about an inch away from the solenoid) and then, as Walt pointed out, the solenoid not having enough current once hot.

    The ring connector I had installed on the wire coming from the "start" switch was for a smaller 14-16 ga wire. I replaced it with the correct size ring connector and so far it looks like that helped. I drove around this morning and haven't had the weak start happen yet. Will keep testing. If it happens again, I'll try Walt's suggestion of running an extra wire from the "start" switch to the solenoid.
     
    Last edited: Jun 25, 2011
  17. Jul 4, 2011
    double R

    double R Member

    Reseda, CA
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    so far so good!

    so far it's only been cleaning up connections and replacing one of the undersized ring connector on the solenoid from the "start" switch...

    amazing how one undersized connector can cause all that...
     
  18. Jul 4, 2011
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    Yep-- those delco solenoids were always a problem and GM knew it.
     
  19. Jul 19, 2011
    codepoet82

    codepoet82 New Member

    Seattle, WA
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    I'd just like to say thanks for this comment... I just ran into this thread's exact same problem when I finally took my jeep for a test run yesterday. Started acceptably when cold, but acted like a dead battery when hot. All my connections had all been nicely cleaned up and no difference at all. I saw your comment, and went out and spent $12 on two new battery cables. She starts up perfectly now, hot or cold. I had never even considered there could be corrosion inside the wiring.
     
  20. Jul 19, 2011
    SFaulken

    SFaulken Member

    Renton, WA
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    I don't have a problem with the delco solenoids, I just have a problem with where they mounted them. Ford always had it right, the Solenoid belongs on the firewall, or on the outer fenderwell, where it's nice and cool.

    Delco built good starters, they just mounted the solenoids in the wrong spot.
     

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