How to Repair an Engine Not Cranking Over

engine not cranking over

When your engine is not cranking (turning) over it will be mainly due to three separate areas, first it could be the battery, cables or poor connection, next is the starter motor or it's trigger circuit, and finally a problem with the engine. Some of these things are easy to fix while others can be a little tougher, all in which are described in the guide below. We will go over each one of these issues in order of popularity and ease. Please visit this guide if your engine is cranking over but not starting.

Lets fix it!

The battery supplies voltage to the starter through two battery cables, positive and negative, which need to be clean and tight while being free from corrosion. If you know the battery is good because it's fairly new or you tested it and it passed, you could have a battery connections problem at the terminals or starter motor itself, here are the symptoms of a bad connection.

  • The dash lights are bright you turn the key to engage the starter, then the dash lights go out and nothing happens.
  • The starter begins to work but then it suddenly stops, the dash lights go out and nothing happens.
  • When you turn the key on and there is no electrical power

clean cable terminal

Weak or dead battery, If the battery fails a load test the battery it will need to be replaced with a new or good used battery of comparable size and cranking amps. This can be done easily using everyday tools while wearing protective gloves to protect against residual acid which can be present on a bad battery. You can get an Optima or AC Delco replacement battery which last longer at Amazon, or just head on down to your local parts store for a replacement.

When you turn the key and the lights stay bright but nothing happens? The first thing to look for is the security light flashing. An immobilizer system is built into many vehicles which can disable the starter when this warning light is blinking. Sometimes the system can become activated due to a glitch or a procedural error, if this light is flashing the system needs to be reset.
immobilizer light

Vehicles equipped with automatic transmissions are designed with a neutral safety switch that will not allow the engine to crank over if the gear selector is not in park or neutral. This is the same for standard transmission cars but the switch is designed to detect if the clutch pedal is fully disengaged. This safety feature will not allow the engine to start while in gear. try moving the gear shift to the neutral position and crank the car over if it starts the gear range sensor (neutral safety switch is bad). On a standard transmission car check to see if the floor mat has lodged under the pedal not allowing fully travel.

Checking the fuses can be an easy fix, if an electrical surge occurs or if the fuse ages it can fail causing the starter to not operate. Fuses are located in the interior fuse panel or power distribution center under the hood. Fuse inspection can be done visual or by using a test light, replace any fuse that are found to be bad.
test fuses

The starter relay is next, used in the circuit to supply power to the starter solenoid which engages the starter motor operation. Some vehicles are not designed with this relay in which case you can skip this step. To be sure if your car is equipped with one of these relays check your owners manual or the fuse panel identification information located on the lid of the panel or you can ask one of our technicians for help. When this relay fails it can do so in two different ways, first the relay may make a ticking noise like it's working but the contacts inside the relay are burnt not allowing the power feed of the relay to be transferred through to the starter solenoid. Next the electrical coil winding will fail causing an open circuit not allowing the relay to work (no ticking noise). In either case the relay must be tested and then replaced if found to be bad.

Before the starter motor will work the solenoid that is responsible for it's operation must receive a trigger signal. This signal is the final destination for the voltage which originates from the operation of the ignition switch by the driver. If everything before this point tests or looks okay you will need to test the starter motor trigger wire for power while the key is in the crank position to determine the condition of the starter. This will require you to get under the car and locate the starter motor which is usually on the right or left side near the rear of the engine block and in some cases under the intake manifold like on some Cadillac and Nissan V8 engines. locate the starter solenoid trigger wire which is the smaller of the two electrical connections. Attach a test light to ground and have a helper hold the key to the crank position. Hold the point of the test light on the terminal of the trigger wire on the solenoid, the test light should light up, also test the large power terminal which is connected to the positive side of the battery it should also have power. Do not touch the test light probe to ground while checking for power to avoid a short circuit. If both terminals have power the starter has failed and replacement is required. Sometimes you will hear the starter click but not activate, this is telling you the solenoid is working but the motor part is bad in either case the starter motor has failed. Many times when electrical items fail it's because there is an open electrical connection. This means a sharp vibration can sometimes allow the connection to work again. While tapping the starter housing with a hammer have a helper hold the ignition key in the crank position or rapidly press the start button. This can sometimes shock the connection into working again and allow the starter to turn the engine over. Keep in mind this will only work one or two times, the starter needs to be replaced which you can get delivered by Amazon or the local parts store. 
starter trigger wire

Many abnormal noises can occur while the engine is not cranking over. These noises include grinding, whirring or a loud clunk indicate and mechanical failure of some kind. The starter is a high torque electric motor fitted with a small gear and a mechanism called a bendix. This small gear engages with the large gear called a ring gear on the flywheel if the car has a stick shift transmission, and onto a flex plate with cars fitted with an automatic transmission. The small gear contacts the large gear only when the starter is engaged and then retracts after the engine starts and the ignition switch is let up to the run position. If the solenoid fails it will not push the bendix gear into the flywheel completely which then creates a grinding noise. When this small gear wears or the bendix failed is will cause a grinding or whirring sound which means the bendix isn't working and the starter must be replaced.
starter gear

Once the starter has been removed check the flex plate or flywheel condition. This means observing the teeth of the ring gear which contacts the pinion gear of the starter. If teeth or missing or badly worn the flywheel must be replaced before installing the new starter. Below is a picture of the flywheel on the rear of the engine with the transmission removed.

If the starter makes a single clunk noise and then nothing it might be working fine, the problem could be the engine is not allowing it to work because it can't be turned over due to a mechanical failure of some kind. To start troubleshooting remove the serpentine belt and check to see if each of the accessories such as the water pump, alternator, air conditioner compressor and power steering pump spin freely and are not locked up not allowing the engine to turn. With the belt removed check for internal mechanical failures which can stop the engine from rotating such as a spun rod or crankshaft bearing, broken piston or rod, dropped intake or exhaust valve or a blown head gasket. The easiest way to do this is to see if you can manually turn the engine over by hand. Check for this problem by installing a large wrench or socket with a long handle fitted onto the front crankshaft bolt and try to move the engine, it should be difficult but not impossible to turn. If the engine is locked up it will need to be replaced or repaired. 


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