Diagnosing starter problems, begins with knowing the basics, of how an engine actually starts.
Above all, the engine has to turn over, at the correct speed, before it will start.
However, if that does not happen, this is where diagnosing should start. So, the battery is always the first thing to check.
When diagnosing starter problems, any number of things, can prevent an engine from cranking or starting. Many things have to happen, and in the correct order.
So, the engine turning over, draws air and fuel into the cylinders. Then, that mixture is compressed. And, cranking the engine generates the ignition, and the crankshaft position sensor signals. As a result, if the starter fails to turn the engine or turns too slowly, the engine will not start.
Diagnosing Starter Problems, Common Issues
So, the first thing to inspect is the battery, to make sure it has enough voltage, to operate the starter. A discharged battery may not be capable, of producing enough voltage or amps, to start the engine.
Unfortunately, starting problems are not always easy to diagnose. Sometimes, the starter is wrongly blamed, for a hard starting or no start condition. As a result, some starters, are replaced by mistake.
So, one way to avoid such problems, is to bench test the starter first. After removing your old starter, you can take it to an auto parts store. Most stores can test the starters, current draw and cranking speed.
Any number of things, can prevent an engine from cranking over or starting. An engine needs the right combination of air, fuel, compression and ignition to start. So, if any of these things are lacking, the engine may turn normally. But, be hard to start or not start at all.
When You Turn The Ignition Switch, And, Nothing Happens:
- It may mean, the starter has failed.
- There may be an open circuit in the ignition switch, or starter circuit wiring.
- A failed neutral safety switch, on the transmission linkage.
Vehicles with manual transmissions have a safety switch, on the clutch pedal. As a result, preventing the starter from cranking, unless the clutch pedal is depressed.
Other Causes Of Not Cranking May Include:
- A bad solenoid.
- Loose or corroded battery cables.
- A low or dead battery.
Diagnosing Starter Problems, How To Test The Starter
Using a jumper to bypass the solenoid, is a trick that will show, if the starter spins or not. If the starter works when bypassing the solenoid, the problem is in the solenoid, or ignition circuit.
If an engine cranks at normal speed, but refuses to start, it is probably not the starter. It is possible the starter is pulling too many amps from the battery. As a result, there is not enough voltage left, to power the ignition system and fuel the injectors.
What Is Normal Starter Amperage Draw:
- A good starter will normally draw 125 to 150 amps, when cranking a four cylinder engine.
- And, 150 to 175 amps, when cranking a V-6 engine.
- But, as much as 200 to 225 amps, when cranking a large V-8 engine.
The current draw depends on, the type of starter and the application. So, look up the test specs for your vehicle, to see if the starter is drawing too much current.
Bad Starter Solenoid
So, a bad solenoid, can also be a source of starter problems. The solenoid acts like a relay, to route power directly to the starter from the battery.
Corrosion, poor ground, or poor battery cable connections, will prevent the solenoid from working. As a result, replacement is necessary, if the solenoid is bad or stuck open or closed.
So, How The Starter Actually Works
The starter itself, is a high torque direct current electric motor. Inside is a rotating armature, four brushes and a pair of field coils, or permanent magnets (on new models). The starter uses the opposing magnetic forces of the armature and field coils, to convert electrical energy into mechanical energy.
When You Turn On The Ignition Switch, What Happens:
- Voltage is routed, through a solenoid or relay to the starter.
- As the starter begins to spin, the drive gear extends and engages the teeth, on the flywheel ring gear.
- When the engine starts, the drive gear retracts, and the starter stops spinning.
- An overrunning clutch in the starter drive, prevents the starter from being, over-revved and being damaged.
Cranking an engine is hard work and pulls a lot of amps, out of the battery. The cranking load is even greater, during cold weather. Because, low temperatures thicken the viscosity of the oil in the crankcase, and increase drag. At the same time, the battery has, less amps available. Because, cold temperature slows down the chemical processes, inside the battery that release stored electrical power. This helps when, diagnosing starter problems.
Other Starter Issues
First, continuous and long cranking, is very hard on a starter. Because, it generates excessive heat. Fuel injection has reduced the strain on starters. Because, it takes fewer cranks for the engine to start. As a result, starter sales for newer vehicles with fuel injection, are much lower than those for older vehicles.
Starter Drive And Flywheel Problems ( ring gear )
Watch out for damaged teeth on the flywheel. If the starter can’t engage with the flywheel, it can’t crank the engine. If the starter cranks the engine normally, but you hear a grinding noise after the engine starts. Then, the starter drive may be hanging up.
As a result, preventing the starter drive gear, from retracting away from the flywheel. This can damage both the starter drive gear, and the teeth on the flywheel. This is something you don’t want to see, when diagnosing starter problems.
Starter Replacement Tips:
Starter
When you need a starter, the replacement should have, the same or higher cranking capacity as the original.
Starter Solenoid
One item you should also replace along with the starter, is the solenoid. Solenoids wear too, so replacing this component, will help assure reliable starting.
Battery Cables
Don’t take a chance on damaged or corroded cables, just replace them. It is important to make sure the replacement cables, are heavy enough to handle the amp load.
Ground Straps
Also, be sure to check the engines ground straps. These straps ground the engine to the chassis. Corroded or loose ground straps, create a poor electrical connection. And, can cause slow cranking speeds. The smaller the diameter of the wire, the fewer the amps it can carry.
Upgraded Battery Power, For Cold Weather Starting
Lastly, try a more powerful battery, with a higher cold cranking amps rating. Consequently, it may provide some added kick, for reliable cold weather starting. The average battery, only last about four years. So, if the original battery is more than four years old, replace it.
Charging System
So, a weak alternator may not be capable of, keeping a battery fully charged. And, without a full charge, reliable starting, may not be possible during cold weather. This helps when, diagnosing starter problems. So, replacing the alternator and drive belt, may also be recommended.
Starter Shims, On Older GM Applications
On certain older GM applications, the starter has to be shimmed. So, the starter drive and flywheel line up properly. Reusing the old shims, is no guarantee the alignment will be correct. The installer should measure the drive gear to flywheel clearance, to determine the correct shims to use.
So, many starters have a heat shield over them. This is to protect the starter from heat, from a nearby exhaust pipe. So, don’t forget to replace it. Failure to do so, may cause the starter to fail prematurely, or lead to hot starting problems.
Conclusion
So, once you’ve finished diagnosing starter problems, then you can start to fix it. And, for all issues, the initial troubleshooting is the same. As a result, you always start with the battery.
BY DANNY BENDER
