What causes car engine to crank slowly?

I just had the engine rebuilt 2.0 liter hyundai.  Battery charges as it should at 12.7 Volts.  Alternator bearings and brushes were replaced about a year ago, voltmeter reading on startup drops to 9.4 volts then jumps to 14.6.

8 Answers

Relevance
  • 2 months ago
    Favorite Answer

    Last time I rebuilt an engine, the first start up was very slow. All parts were assembly lubed during the build, but brand new engines always are very tight. Once started, it idled laboriously for the first 20 minutes, then began to idle normally. It is important to not force a new engine while parts bed in. I used that engine for another 85,000 miles, then sold the car- still running perfectly and strong. Take time to let your engine loosen up before you try to drive it.

  • Anonymous
    2 months ago

    The alternator charges the battery at 14.4 volts (approximately). 

    If your voltmeter reads 12.7 volts, then it is inaccurate, or the alternator is not operating.

  • Anonymous
    2 months ago

    Battery is shot.  Load test the battery to confirm.

  • Theo
    Lv 4
    2 months ago

    Might be a starter issue.

  • How do you think about the answers? You can sign in to vote the answer.
  • 2 months ago

    A rebuilt engine can be tight depending on how it was done. Start with a new battery if it is a couple years old or more.

  • fuzzy
    Lv 4
    2 months ago

    9 volts is considered the minimum for an automotive battery when starting. Generally this indicates a weak battery, though very high current draw from a failing starter can draw down a questionable battery. Have the battery tested.

  • 2 months ago

    You need 13.7 volts for the battery to charge. Try cleaning the battery posts and the inside contact area of the battery cable clamps. Go to an auto parts store to have the battery and charging system tested for free.

  • 2 months ago

    Starter motors have four brushes, if any one fails it'll lose half its power.  Also any bad connections between the battery to the solenoid, the solenoid to the motor, and the engine earth back to the battery will cause it to lose power.  Bad connections tend to get very hot so if anything's getting hot then check it out, but be careful because when I say very hot I mean it.  If your battery's at 14.6V from driving it, not from putting a battery charger on it then that suggests that your alternator is working properly and that you have a good battery.

Still have questions? Get your answers by asking now.