Most car owners and drivers are used to engaging the footbrake when slowing down their car under normal conditions and in an emergency. But this process isn’t ideal if you want your vehicle to last its lifespan.
Would you prefer to drive your car under the assumption that its components should be engaged in a certain way and end up damaging it? I’m sure you don’t want that!
Kindly take the time to find out what engine braking is, how engine braking works, the causes of engine braking failure, its pros and cons, as well as other meaningful information about the operation.
What Is Engine Braking?
Engine braking is the process of slowing the vehicle down by shifting to a lower gear, letting the engine absorb energy instead of relying on the brake pedal and friction brakes.
On a manual transmission equipped car, a skillful driver will shift to a lower gear when decelerating. The momentum of the vehicle (kinetic energy) drives the engine that way, and since the engine isn’t providing power but is being driven, it resists the driving force.
The wheels apply this power through the drivetrain and axles, where it is applied to the engine itself.
During deceleration on fuel injected engines, the fuel injectors are turned off to prevent unnecessary fuel delivery when there’s absolutely no reason the engine needs fuel. This not only helps with economy, but it also helps prevent exhaust backfiring.
It’s also during this kind of non-powered deceleration that a “crankshaft learn” waveform is stored in the PCM. That waveform and the cam sensor input is used by OBD2 software algorithms to identify misfiring cylinders. This helps slow the vehicle down and can reduce brake shoe and pad wear.
Similarly, hybrid and electric vehicles will alter their electronics during deceleration so that the momentum of the vehicle drives the motors in the transmission/transaxle, creating a burst of power that charges the battery.
How Does Engine Braking Work?
When the accelerator pedal gets released, the air intake valve is closed and a vacuum is created, which prevents airflow into the cylinders.
There’s a decrease in energy that starts to create a braking force, which helps slow down a vehicle by lowering the engine speed, or RPM.
Resistance in the engine is transferred through the drivetrain to the wheels. Some of the braking force produced is from friction in the drivetrain, but most of it is caused by the vacuum that was created from the lack of air.
The result is a process that helps slow down a vehicle without the use of a foot brake.
Types of Engine Brakes
#1. Compression Release Brakes (Jake Brakes).
Compression release brakes, commonly known as Jake brakes, are used in large diesel trucks and buses.
When activated, they open exhaust valves near the end of the compression stroke, releasing the compressed air trapped in the cylinder. This release of pressure slows the engine dramatically, providing a powerful braking effect.
Jake brakes are extremely effective but also very loud. So loud, in fact, that many cities post “No Jake Brake” signs in residential areas to reduce noise pollution.
#2. Exhaust Brakes.
An exhaust brake restricts the engine’s exhaust flow, creating backpressure in the cylinders. This backpressure slows the pistons and, as a result, the vehicle. Unlike Jake brakes, exhaust brakes are quieter and can be used more often in populated areas.
They’re a favorite for diesel pickups and medium-duty trucks because they offer good braking power without too much noise.
#3. Manual Downshifting (Using Transmission).
For everyday drivers, the most common form of engine braking is manual downshifting, either by shifting to a lower gear in a manual transmission or selecting “L” or “2” in an automatic.
When you downshift, you increase the engine’s RPMs, allowing the engine’s compression to slow the vehicle instead of the brake pads. This method is particularly helpful when driving downhill, towing, or trying to maintain control on slippery roads.
What Causes Engine Braking Failure?
Most cars, especially modern ones, are equipped with computerized systems that display any issues that need to be addressed by the car owner; one such issue is engine braking failure.
Engine braking failure does not happen automatically; it can be caused by one or more of the following.
#1. Engine rough idling.
Engine rough idling is one of the main causes of engine braking failure. Rough idling is usually caused by defective or damaged spark plug wires or spark plugs.
Engaging the engine braking becomes difficult when your car’s engine runs roughly, leading to a failure of the engine braking.
#2. Engine stalling.
Many factors can cause your car’s engine to stall. Lack of fuel, a dead alternator, a defective coolant sensor, or forgetting to depress your car’s clutch or switch to neutral when stopping your vehicle could make the engine stall, among other reasons.
In any case, if your car’s engine consistently stalls, you will most likely experience engine braking failure.
#3. Engine misfiring.
Defective spark plugs, a clogged fuel injector, a defective oxygen sensor, etc., are some of the reasons why your car’s engine may misfire.
Meanwhile, when your car’s engine misfires, engaging engine braking becomes impossible. It will likely result in engine braking failure.
When to Use and Avoid Engine Braking?
While beneficial, engine braking isn’t the right tool for every situation. Knowing when to apply it is just as important as knowing how.
When to Use It?
- Steep Descents: This is the golden rule. Always use a lower gear when going down mountains or steep hills.
- Highway Exits: Instead of braking hard at the last second, lift off the gas early and coast down the off-ramp.
- Approaching Red Lights: If you see a light turn red in the distance, lift off and let the engine slow you down. You might not even need to touch the brake pedal until the very end.
- Traffic Flow: In moderate traffic, keeping the car in a lower gear allows you to adjust to speed changes without constantly flashing your brake lights at the driver behind you.
When to Avoid It?
- Emergency Stops: If a child runs into the road or a car pulls out in front of you, slam on the brakes. Friction brakes are designed for maximum stopping power. Engine braking is for gradual deceleration.
- Icy or Slippery Roads (With Caution): This is a debated topic, but caution is required. If you downshift aggressively on ice, the sudden drag can cause the drive wheels to lose traction and lock up momentarily. Since your ABS (Anti-lock Braking System) works on your hydraulic brakes, not your engine, it cannot correct this slide. On very slippery surfaces, gentle use of the foot brake allows the ABS to keep you safe.
Benefits of Engine Braking
Engine braking offers several benefits that can help prolong your vehicle’s lifespan. Here are some of the most common ones.
#1. Reduces Brake Wear.
By relying on the engine brake, parts like the brake pads and rotors won’t get used as much, which means it’ll take longer for them to wear out.
Engine braking also reduces the chances of brake fade, which occurs when there’s too much heat between brake parts to the point where it’s nearly impossible to create negative force to slow the vehicle down.
#2. Better Vehicle Control.
The vehicle stays in gear whenever you make use of engine braking, creating a natural, smooth, and consistent force. Pedal braking, on the other hand, can upset the vehicle’s balance and make it harder to control.
#3. Improved Fuel Economy.
Again, during engine braking, the powertrain control module (PCM) cuts off the fuel supply to the injectors, which slightly improves the vehicle’s overall fuel economy.
#4. Controlled Downhill Driving.
Driving downhill while the gear is in neutral can make the brakes work harder because of gravity. Engine braking can prevent the brakes from generating too much heat caused by friction and lets the driver control the vehicle better.
#5. Improved Stopping Ability.
Engine braking and applying the foot brakes at the same time can lead to a faster stopping time while reducing wear on several brake components.
Is engine braking safe?
Many drivers consciously use engine braking to save their brakes. By allowing the engine to take on some of the work of slowing down the car, they use the brakes less frequently and less forcefully.
With less wear and tear on the brake pads and rotor, these parts last longer. Engine braking can also help reduce the possibility of a brake fade, a condition where the brakes become less responsive.
Additionally, during engine braking, fuel-injected engines cut off the fuel supply, meaning that the engine isn’t consuming fuel while it’s helping to slow down the vehicle.
However, while engine braking can help you reduce brake wear and save some gas, there are some downsides.
If you use this technique suddenly or aggressively, especially if you downshift too quickly, you can increase wear and tear on the clutch and gearbox. It may also take a toll on your car’s drivetrain.
When you use engine braking, you’re essentially redirecting the heat that the braking system would normally absorb into the engine.
So, think about whether protecting your brakes, which are relatively inexpensive to replace, is worth placing additional stress on your engine, which can cost thousands of dollars to repair.
Another thing you should consider is safety, particularly when driving in traffic. When you use the actual braking system to slow down or stop, your brake lights come on, signaling to drivers behind you that you’re decelerating.
However, when you rely on engine braking alone, your brake lights don’t come on, which could catch other drivers off guard.
Without that visual cue, your slowing down might come as a surprise, increasing the risk of a rear-end collision. So, you have to be mindful of when and how you use engine braking, especially in traffic or when driving close to other vehicles.
FAQs.
Q: Is engine braking bad for cars?
Many people have the misconception that engine braking is bad for a car’s drivetrain. They believe it can affect the car’s transmission, cause the engine to wear out, or waste fuel.
If you are asking, “Is engine braking bad for an automatic transmission?” Or you used to believe this myth; kindly debunk it.
Engine braking is not bad for your car; neither does it affect your car’s transmission, its engine life, or result in fuel wastage. Engine braking slows your car’s wheels without using the brakes.
However, you must endeavor to perform engine braking correctly without shifting very frequently so that it doesn’t result in the wear of your car’s transmission if you drive a vehicle with a manual transmission. It could also result in higher temperatures for those who drive automatic transmission cars.
Q: Can I brake without a clutch?
If you are considering engine braking vs. clutch braking, you can possibly brake without pressing down the clutch, especially in traffic.
When you approach traffic or need to slow down or stop your car, you can release the gas pedal and brake directly without engaging the clutch.
It is typical to clutch down when changing gears; this helps disengage the gears and the engine from the wheels.
As a matter of fact, keeping your clutch down unnecessarily can alter a driving test. It is referred to as “Coasting.” It reduces your ability to control and stop your vehicle’s engine while driving.
Q: What happens if you don’t break your engine?
Breaking in your car’s engine helps minimize early wear. It helps to ensure that your car’s bearings and other moving parts settle altogether and gradually wear evenly.
If you don’t break your engine, you could have piston rings that don’t seat properly, and your car will burn oil. You could have your car’s camshaft lobes wear out, resulting in valves opening and closing at the wrong timing and speed.
Also, the crankshaft bearing may start to spin and destroy itself, thereby making your car’s engine seize up. These scenarios can utterly damage your car’s engine. So, it would be helpful to break into your car’s engine.
Q: Why do I have no engine braking sign?
If you experience a situation where your vehicle does not project an engine braking sign, especially if you drive a truck, then it is a warning against using your engine to brake.
Engine braking in trucks often produces loud noises when the driver downshifts to slow the vehicle without applying the brakes.
Q: What happens if you press the brake without a clutch?
Pressing the brake to slow down your vehicle and eventually stop without first pressing down the clutch is possible.
However, the clutch ought to be pressed down to disengage the power from your car’s engine to the gearbox so that the brake can seize the rotation of the wheels with any more force coming from the engine.
Meanwhile, if you press the brake without the clutch, you would be slowing down or stopping the wheels without disengaging the engine’s power from the gearbox, leading the wheels to receive more force to rotate, even though you are braking. This situation can quickly damage your car’s gearbox if consistently repeated.
Q: What is the difference between an engine brake and an exhaust brake?
If you are contemplating an engine brake vs. an exhaust brake, they function differently. Although an exhaust brake retards power in a diesel engine, its operation is not the same as that of an engine brake.
The engine brake releases compressed air via an exhaust valve when engaged; while the exhaust brake holds the compressed air in the car’s engine when slowing down the rotation of the crankshaft, thereby reducing speed. You may want to learn about the disadvantages of an exhaust brake.
Final Words
Understanding the difference between applying a footbrake and engaging engine braking is essential. This article has unveiled all you needed to know for those who were asking, “What is engine braking?” or “What is engine braking in a truck?”
Henceforth, it would be best if you master using engine braking when necessary, rather than constantly applying your car’s footbrake. If you do this, you will save your car’s gearbox and other braking components from premature damage.