Hot Starting Problems

 (The car starts OK when cold!)

Hot starting problems have
five principal causes:
  • Starter
  • Tight Engine
  • Engine Malfunction
  • Fuel problems
  • Electrical
The cause can be isolated
using the guide at the right.

* NOTE!  "Crank" refers to the starter turning the engine over, not sucessfully starting the engine.

Engine doesn't
crank at all

Do you hear a single click at the solenoid?

Have someone turn the key to the start position while you check the voltage at both sides of the the solenoid.  If the voltage drops below 10V at the battery side, go to "Low Battery Voltage".  If the voltage stays above 12V on the battery side, with under 9V on the starter side, go to Low Starter Voltage

Does the solenoid chatter or have no reaction when you turn the key to start?

Check the battery and battery cable connections (including the battery and engine grounds).

A good battery will show 12.5V unloaded and even 9V cranking the engine.  You can get some idea of the battery's condition by checking the battery voltage by loading it with the electric fan and headlights.  It should maintain 11.5V under load.

Also, see the section on "Engine cranks, but very slowly".

Engine cranks, but very slowly

Low voltage at battery, starter

See here

and below

Normal voltage at starter when cranking (8.5V or better)
  • Tight engine
  • Defective starter with worn bearings
  • Too much ignition advance at low RPM
    (Starter will intermittantly strain to turn the engine over.)

Engine cranks fine, but never fires

No spark found at the coil connection?

(Also check for spark at the distributor

Possible causes related to heat:
  • Bad coil
  • Bad "spark box".

See also the section on intermittant firing below

Engine cranks fine, with intermittant firing

If there is a strong fuel smell, either in the engine compartment or at the exhaust pipe, see below.
Too-high float level. Adjust float level lower
Fuel percolation during hot-soak floods engine. Install insulator between intake manifold and carburetor

See also Engine cranks but never fires

Low Battery Voltage

Sometimes a battery will show 12+ Volts without load but the voltage will drop considerably when you crank the engine.  This is due to one or more of the following factors:
  • Bad cell/internal connection inside the battery.
  • Bad connection to a battery terminal, the starter solenoid (either side) or the starter.
  • Starter internally shorted when hot.  You will notice that the current draw is very high making the voltage low everywhere.
  • Sometimes

Low Starter Voltage

Bad starter solenoid

Check by bypassing the solenoid with a heavy duty jumper cable, or by removing the connection from the battery side and touching to the starter side.  Replace the solenoid if the engine cranks.

Starter defective, causing high load

It's not unusual for a starter to "seize" at high temperatures if the internal clearances are excessive. You may ameliorate the problem (temporarily, usually) by surrounding the starter with high-temperature insulation.  It that doesn't help, replace the starter.

Engine very tight

See the section: Engine cranks, but very slowly