Both manual and automatic transmission cars are susceptible to stalling, and this can happen due to a number of reasons. Whilst stalling may sometimes occur through accidentally mistiming your clutch and gas pedals, it is useful to know when an engine stall is actually a mechanical fault.
In this guide you will learn why car stalling happens and how to identify what is causing the issue if it’s a fault. If you need replacement parts to fix the problem, take a look at our wide range of alternators, fuel pumps and clutch kits, which will get you driving smoothly again in no time.
How does a car stall?
In our breakdown of how the clutch works in vehicles, we talked about how cars start moving by transferring power from the engine to the wheels. Stalling occurs when the engine plate and clutch plate are connected together (commonly known as the biting point) but are not rotating at the same RPM (rotations per minute). If this happens, the engine will cut out and stop sending power to the rest of the car, which causes it to stall.
Can you stall an automatic car?
Automatic car stalling occurs much less frequently, due to the engine handling what gear the car needs to be in. The torque convertor will then ensure transition fluid keeps the engine parts lubricated and running smoothly.
This doesn’t mean however that an automatic car can’t stall, as this may be happening due to a mechanical fault.
Types of car stalling
Transmission stalling
Stalling in this way is common, particularly if you are a learner driver or getting used to a new car. There are several situations in which transmission stalling can happen, including:
- Driving in a gear not suited to the speed you’re travelling at (e.g., being in 5th gear at 20MPH)
- Hill starts
- Starting the car and coming to a stop
The key to overcoming transmission stalls is understanding your car’s biting point, which we mentioned previously as being the point of contact between your car’s engine and clutch plates. This acts as your indicator to apply more acceleration and get the car going, without the engine stalling.
Mechanical stalling
If your car stalls while driving, this can be because of a mechanical fault, instead of driver error. These faults can take different forms and should normally be assessed by a professional mechanic:
- Battery and alternator – the alternator charges your battery and other parts of the engine. A faulty alternator or battery can mean power is not reaching essential components
- Fuel pump – a damaged fuel pump can result in the engine not receiving enough fuel to function properly
- Empty tank – an obvious but common cause of mechanical stalling. This can occur due to a faulty fuel pump or if the tank hasn’t been filled up recently
- Fuel pressure – stalling on a hill can suggest a problem with your car’s fuel pressure
- Airflow – sufficient airflow is vital for keeping your car’s internal parts cool. Damaged or clogged air filters can interfere with this airflow and cause overheating
- Braking – stalling whilst braking is possibly due to a leak in the ABS (anti-lock braking system)
- Air & fuel mixture – an inadequate mixture of air and fuel in an engine means the ignition coils can’t create the spark needed to start the car
During any instance where a fault causes your engine to stall, you should always pull over when safe and seek immediate help from a mechanic. Important systems such as braking can be severely impacted by these faults, potentially putting yourself and others around you at risk.
Looking after the transmission in your car will help it run smoothly for longer. Check out our guide on how to identify and fix a leak in your car transmission should one occur.