Why does my car sometimes fail to start?

Thursday March 26 2020


By Paul Kaganzi

Hello Paul, my Toyota Harrier has behaved strangely on two occasions. I tried to start it and I just heard a whirring noise like a running motor without the car starting. After three attempts, it started. I am worried one of these days I might get stranded. What could be the problem and how can we solve it? Vanessa

Hello Vanessa, I can imagine how unsettling it can be to turn the ignition key of your car and fail to start it. What you describe as an intermittent whirring noise like a motor running maybe a faulty starter unit.

The starter is made of two main parts; the primary motor which turns the crankshaft to start your car engine and the solenoid, which engages the starters’ drive gear and completes its electrical circuit. These are the starter components that usually fail due to age or rarely user failure.

One can service, repair or replace the starter unit depending on the extent of damage or component which has failed. There are a few common symptoms one can use to tell why the starter unit has failed: free wheeling, intermittent failure to start, grinding noise, starter stays on when the car has started or smoke from the starter unit. In your case the symptom is free wheeling.

When you turn the key for ignition the starter makes a whirring noise but does not crank the engine. This means the starter gear does not engage the fly wheel to start the engine. Common causes of starter free wheeling are a bad solenoid or failure of the throw out fork. In this case you can either buy a new starter or quality remanufactured one.

There are importers of quality broken engine parts, you would get a better price deal as long as its pre tested by a car technician prior installation.


Intermittent failure to start may be a result of a bad relay which is supposed to send the electric current. Occasionally it may be the result of loose or corroded battery terminal connections. Grinding noise from the starter are due to worn out gears which may damage the fly wheel, this calls for starter unit replacement.
When the starter motor stays on even when you release the key, this means the contacts of the solenoid are welded together or relay is stuck in the closed position, a car electrician should fix this immediately or else it can damage the costly flywheel.

A smoking starter unit will mean power is continuously being supplied due to a short circuit or prolonged starting, which does not allow it to rest.