What can keep a car from turning over?

Answer 1

You have not provided enough information for a proper diagnosis so you are getting a "general" answer. The specific information missing is the history of the condition. Does the engine "try" to turn over (IE can you hear the starter engage and move the crankshaft at all). Has this car been in storage (IE not started) for a long time? Has any work been done/parts replaced before the no-crank/turnover condition was discovered? Is the problem not there when the car and engine are stone cold?

If ANY parts have been replaced or major assembly work done (such as trans or engine rebuild) then look very closely at that work as an error was likely made during reassembly.

If the engine tries to turn over and/or was fine before it was stored/not started for a long time then suspect the battery and/or cables (especially the ground cable).

If the car was in use and suddenly stopped cranking (IE "I was drove to the store and it would not start when I returned to the parking lot, it would not even try to crank) then suspect the starter relay/solonoid and starter itself.

If the condition does not exist when engine and under the hood are "stone cold" (as in sat outside overnight) then the starter is almost certainly failing.

Make the following tests with a fully charged, known good, battery...

1). If the car is in a well ventilated area (IE no GAS fumes under the hood!) and you have enough clearance to reach it with a "throwaway" thick-shaft screwdriver then you can test the relay/solonoid by shorting across the two big studs (caution! sparks WILL fly and the screwdriver will be damaged!). If starter engages and cranks the engine then the cables and battery and starter are likely all right and you should look into the relay/solonoid or it's control circuit as the culprit.

2). Turn on the headlights and attempt to crank the engine over while watching them.

(Note: Immediately after cranking CAREFULLY feel each of the cables, at both ends, for being "hot" (take care not to burn your fingers!). If any one end is noticeably hotter than the others then that is your most likely target for repair.)

If the lights "go out" or dim severely then the starter is either drawing too much power (as in shorting internally) or the battery cables/ends are corroded where they contact the battery and/or cable's copper wire and/or engine/body contact-point.

(Note that you may NOT be able to see the corrosion, the cables/ends may "appear" clean but there could still be enough corrosion hidden in the metal-to-metal contact surface area to cause this symptom.)

3). With the headlights off, place a digital voltmeter set to 20 volt-range "across" each of the cables in turn (IE one probe on the battery POST itself, NOT the cable clamp, and the other on the metal near where the other end of the cable connects. IE engine block or starter relay/solonoid stud or vehicle body, wherever that particular cable connects).

Attempt to crank the engine over again while reading the voltmeter.

If the voltage you read is more than 0.3 volts (that is 3 tenths of a volt) then you have found a problem with that cable/connection.

Good luck