Possible Problems That Might Go Wrong With Your Automobile Engine

Troubleshooting is practical wisdom, that is, using knowledge in a logical manner to eliminate the causes of a malfunction. One must not to be afraid to consider the most 'right in front of your face' reason, like running out of gas, ack!, (or petrol for those across the pond.) One can use this guide hopefully also for the increased sagacity for preventative mechanics. You will need: A complete set of Craftsmen™ or Snap-On™ or whatever tools, a garage with lifts, and probably a certified mechanic, but some of these things one might do oneself. Also, I hope I humanized a mechanical mantra that seemed to be originally written by a boring robot. Oh, and you will need some Lava or Orange soap, lots of paper towels, and most emphatically -- NO SMOKING!

The Engine, Powerhouse of Today's Mobility: A Kind of Triage Checklist

Motor cooled down, he went down,
That's when I heard that highway sound.--
"Mabelline," Chuck Berry

    (1) The engine will not turn when attempting to start.

  1. Check battery terminal connection for loose attachment of wires or corrosion, tighten and or clean.
  2. Check for a discharged battery with ignition turned on, and see if lights or windshield (windscreen) wipers work: if not, battery has lost all its charge.
  3. The automatic trans-axle maybe not totally positioned in Park or Neutral, or for manual, clutch not completely pressed
  4. There maybe broken, loose or disconnected wiring in the starting circuitry, starting with the battery, then the starter solenoid and finally the ignition switch.
  5. Starter motor pinion could be jammed in the flywheel. For manual trans-axles, place in gear, and rock the vehicle to force the engine to turn. Remove starter as soon as practical to inspect pinion and flywheel.
  6. Starter solenoid may be faulty.
  7. The starter motor might be malfunctioning.
  8. The ignition switch possibly has failed.

    (2) The engine turns but will not start.

  • There is no fuel in tank. Doh!
  • Is the carburetor or fuel injection system failing?
  • If the engine rotates slowly, very possibly the battery has discharged. See (1).
  • Battery terminals could be loose or corroded. See (1).
  • Fuel pump pooped out.
  • Damaged ignition components, maybe by excess water.
  • Worn, and or improperly gapped spark plugs.
  • Messed up wiring as described previously.
  • If one has a distributor, it might have come loose -- check by turning it until engine starts.
  • Inspect for bad ignition coil or wires connecting to it.
    1. (3) The starter motor operates but does not turn the engine.

  • The starter pinion may be sticking. Inspect the removed starter
  • There may be broken teeth on the pinion or the flywheel, inspect after removing the drive-plate access cover.
    1. (4) The engine is hard to start when cold.

  • As discussed in (1) the battery may be discharged.
  • A problem in the fuel or electrical systems may need to be checked.
  • The carburetor may need overhauling.
  • There may be a damaged distributor rotor, or covered with carbon tracking.
  • The choke control may be stuck or not working.
    1. (5) The engine is difficult to start when hot.

  • The air filter could be clogged.
  • There may be a problem with the fuel or electrical systems.
  • The carburetor or fuel injection systems may be starved for gasoline. (Especially if one hears all systems crying, "Feed Me!") Perhaps a vapor lock.
    1. (6) The starter motor is emitting loud noises and running very rough when engaged. (And you do not own a Harley or a Hot-Rod.)

  • Examine the likelihood of broken or worn pinion or flywheel gear teeth by removing cover at rear of engine, if available.
  • Check for loose or missing bolts on starter motor mount.
    1. (7) The engine engages but stops immediately.

  • Are there loose or faulty electrical connections at the distributor, coil, or alternator?
  • Fuel or electrical system malfunctioning should be considered.
  • Not enough fuel could be making it to the carburetor or fuel injectors, and one should check the fuel pump.
  • If there is a vacuum leak at the gasket surfaces of the intake manifold, or carburetor and throttle body then one must re-tighten nuts and bolts tightly, and re-attach or replace vacuum hoses.
    1. (8) The engine jerks or is kind of wild during idling. Whole lotta shakin' goin' on.

  • Vacuum leaks may be a possibility so check the mounting bolts and nuts at the carburetor and throttle body and at the intake manifold for tightness. Make sure all vacuum hoses are connected and in working shape.
  • Fault in the fuel or electrical systems.
  • Check for leaking EGR valve or clogged PCV valve.
  • Is the air filter overly dirty.
  • Is the fuel pump not delivering sufficient gas to the carburetor or fuel injection sytem.
  • Tune up and or adjustment needed for the carburetor or throttle body.
  • Perform a compression check for the possibility of leaking head gasket.
  • Are the camshaft lobes worn.
    1. (9) The engine is missing at idle speed.

  • Gap the spark plugs and check for wear.
  • It could be the old faulty fuel or electrical system.
  • Check for frayed or disconnected spark plug wires.
    1. (10) The engine is missing throughout driving speed range.

  • Did the fuel system get fouled, or did the fuel filter get blocked.
  • Correct too close or far gapped spark plugs or replace.
  • The fuel and electrical systems may have failed.
  • The ignition timing could be off.
  • If one has a distributor cap it could be cracked, or other parts might be broken, but there could just be loose distributor wires.
  • The spark plug wires should be checked for integrity.
  • Emission components that have "gone south" could be to blame.
  • After removing the spark plugs, test for low or uneven cylinder compression with a gauge.
  • The ignition system could be insipid or null.
  • There could be vacuum leaks at the carburetor and throttle body, and or intake manifold, vacuum hoses.
    1. (11) The engine dies (konks) out. (If on railroad tracks get out of car FIRST!)

  • After referring to the VECI label, examine the idle speed.
  • Water or foreign substances may be in the fuel system or the filter is clogged.
  • Are distributor parts dinged or wet?
  • System sensors could be malfunctioning for fuel or emission information system.
  • The emissions system components out of commission.
  • Spark plugs, again, gapped or how are the wires?
  • Sounding like a broken record: there could be vacuum leaks at the carburetor and throttle body, and or intake manifold, vacuum hoses. (See 8)
    1. (12) The engine is woefully weak. (Maybe it is a Yugo.)

  • The ignition timing could be off.
  • It could be the old faulty fuel or electrical system.
  • Excepting the DIS system, see if there is too much play in the distributor shaft as well discern for a damaged rotor, cap, or wires.
  • Spark plugs: gapped correctly or are the wires worn or disconnected?
  • There may be an out of adjustment or worn carburetor or throttle body.
  • Is the coil defective?
  • Are the brakes locking up?
  • Check the automatic trans-axle fluid level.
  • A slipping clutch will rob power.
  • Dirt in the fuel system, or a overly gooped up fuel filter can sap energy.
  • Emissions systems control systems: error!
  • Stop using that cheap 85 octane junk and move up to high octane! (Especially if the automobile requires premium.)
  • Test cylinder compression pressures with a tester looking for leaking valves and or a blown head gasket.
    1. (13) The Engine explosively backfires. (Which could cause a neighbor on witness protection program to have a heart attack...but that is another node.)

  • Emissions systems out of whack.
  • Fuel or carburetor problems perhaps.
  • Ill-timed ignition.
  • Secondary ignition system miscues like cracked spark plug insulator, bad wires.
  • The emissions systems must be considered.
  • See section 8 for discussion of vacuum leaks.
  • The valves could be sticking.
    1. (14) One hears metallic tapping or tapping/banging sounds from the engine during acceleration or going up an incline. (First eliminate tinnitus.)

  • Get a better octane grade of gasoline (Do not be penny-wise and pound foolish, or is that the other way around?)
  • Electrical or fuel system boop-up.
  • Fix ignition timing.
  • Re-tune carburetor.
  • Check the spark plugs referring to the VECI label under the hood (bonnet), and re-examine spark plugs and their wires for damage.
  • The distributor could have been hurt or just plain "wore out."
  • Suspect emissions systems.
  • Vacuum leaks as problematic discussed in (9).
    1. (15) The engine 'diesels' (Like some metal zombie, after cutting the car off -- it will not die!)

  • Idle speed could be too fast.
  • The fuel and electrical, ack!, again.
  • The ignition timing may be off.
  • Maybe the thermo-controlled air cleaner heat valve is not running a hundred percent.
  • Engine may be running too hot. Check shot thermostat, clogged radiator, or a failing water pump.
  • Check the anti-dieseling solenoid.

  • Source:
    Dodge Caravan, Plymouth Voyager, Chrysler Town & Country; Haynes Automotive Repair Manual, Curt Choate, Mike Stubblefield and John H. Haynes; Haynes Publishing Group: Somerset, England; Newbury Park, California. (1994)

    I must not forget to include all the car songs, man, of the sixties, from Jan and Dean, Danny and the Daytonas, and the Beach Boys -- for their ethereal inspiration. (Also: "...gotcha fuel line and a handful of 'ludes..." from David Bowie.)

    >>Also, a big heads up to N3Bruce, who told me that vapor lock was another reason for engine not to start, and for engine dieseling, a problem with the anti-dieseling solenoid

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