Checks to Make When Your Car Won’t Start When Warm

Question: My 1973 1200 Beetle will start perfectly from cold but sometimes if the engine is warm it is as though the battery has gone flat and the engine simply refuses to turn over. If I leave the car for a few hours to go cold it will start again no problem. Is it just time to buy a new battery and be done with it?

Skill Shack says: If the battery has enough power to turn the engine over when it’s cold it should be able to do the same when the engine is hot. That said, battery performance can be affected by extreme under-bonnet temperatures, but we’re talking high-performance-type temperatures here, and anyway, the Beetle’s battery is positioned away from major sources of heat under the rear passenger seat.

We think the problem is with either the starter motor or its cables. Check the connections and cables from the battery back to the starter. If they look OK, try substituting the live and earth cables in turn with a jump lead to the respective terminals on the battery the next time the problem occurs. If the engine turns over, replace the cable you are substituting. If the leads test fails to turn anything up, then the starter motor is probably the culprit. Remove it and get it tested and repaired at an electrical factor.

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9 Responses to “Checks to Make When Your Car Won’t Start When Warm”

  1. A mcmeekin
    A mcmeekin

    Dont forget about the starter bushing in the gearbox housing replaced alot in my day

  2. Split pin
    Split pin

    I’ve had this problem on a couple of cars. I found the fuel pipe to carburetor was getting hot a vaporizing fuel. I repositioned pipe and wrapped it in heat reflecting tape which cured my problems.

    • jimgreenhillj

      Hi I have had the same problem, question here is the engine won’t turn over, if fuel vaporising would the engine still turn over? If yes makes me think back to the starter cable. I took of connections cleaned and put back, never had the issue again but it only happened once not sure if fixed or conditions not reappeared

      • Customer Service
        Customer Service

        Hi, and thanks for contacting Skill Shack with Practical Classics.

        Skill Shack works in partnership with Practical Classics Magazine, which can provide in-depth answers to your question through their ‘Ask Our Experts’ pages. If you’d like to direct your query to our team of experts will be able to help.

        Kind Regards,
        The Skill Shack Team

  3. Kim Allen
    Kim Allen

    Try changing the condenser on the distributor, they can pack up when hot!

    • Peter Francis
      Peter Francis

      Yes, I’ve had that problem too, also had a coil that broke down when hot. However, this should ‘t stop the engine turning over, I’d check the starter earth and the better cables.

  4. John harris
    John harris

    I had this problem on an xr3i when it was hot it wouldn’t like a flat battery found out the starter cable was close to the distributor and inductance from the cable advanced the distributor but only when the engine was hot

  5. Cliff

    I would check the positive cable if it gets hot reroute or put a thicker one in .this was a common fault with falcons Xb. Xa. Etc there positive cable was about 1 metre long and used to get hot