With so many moving parts in an internal combustion engine, something is bound to creak, tick, groan or whistle at some point. While some of the noises are normal and form part of the normal engine noise from under the hood, others are a bit strange and unexpected.
Ticking is one of those abnormal noises that should always get you worried. Normal ticking from fuel injectors and other components tap around normally is a bit subdued, and you shouldn’t hear it under normal circumstances.
What Could Cause Ticking Noises in My Engine When Idling or Accelerating?
Since some ticking noises are normal, we will start with those you shouldn’t worry about. Luckily, you will only hear the mild noises when parked at a silent place with the hood open or driving down silent roads.
Some of the normal problems include:
Firing Fuel Injectors
Fuel-injected engines use a fuel delivery device with electronically actuated valves with return springs.
An electric signal from the power train control module pushes a plunger open, letting some fuel spray into the combustion chamber. After this, the return spring pushes the plunger back, closing the outlet.
This back and forth will happen multiple times per second, depending on how fast your engine runs.
As the plunger hits the end of its travel distance, it will naturally make a gentle tapping noise. Normally, the noise is gentle and subdued by the rest of the hum and noise from the engine.
However, you can pick up fuel injector ticking if one or more injectors are faulty. They’ll be less graceful and ‘tap’ louder.
The Purge Valve
Your purge valve is an important recirculation device that releases gas stored in the charcoal canister back into the engine’s intake for combustion.
This helps make the engine more efficient and reduces how much pollutants it releases into the environment.
You could get some bit of tapping and ticking as the purge valve opens and closes.
Your PCV Valve
A Positive Crankcase Ventilation (PCV) deals with gases leaking past the pistons and into the crankcase. Instead of venting these gases into the environment like older cars, all manufacturers from around 1965 started recapturing these gases with the PCV system and pushing them back into the intake manifold.
The PCV is a one way valve that will let gases out of the crankcase but won’t let anything in.
This is another waste control valve in a modern engine with an actuating plunger. You could hear some clicking noise from the valve. However, you should consider replacing the valve if it ticks more than it used to.
Now, time to look at other not-so-normal problems that could make your engine make a ticking noise.
An Exhaust Manifold Leak
Though rare, a leak in the exhaust manifold could cause some ticking noise while idle or in accelerating. While most leaks will cause whistling sounds as the air leaks, you could get a ticking noise if the escaping air vibrates a metal part in the exhaust manifold.
You can still keep using your vehicle with an exhaust manifold leak but fixing it as soon as possible is good for your engine in the long run.
Low Oil Levels or Low Oil Pressure
Having a ticking noise from your engine and low oil pressure (or low engine oil level warning) is problematic.
The ticking means your engine is starved of lubricant, and crucial parts are rubbing against each other.
For instance, a dry valvetrain will make ticking noises as the engine runs. If you don’t top up your engine oil and find out why you are losing oil in the first place soon, you will ruin your engine.
Make a habit of frequently checking your engine oil levels, monitoring the engine oil pressure by looking for the pressure warning light, and inspecting the bottom of your car for any signs of a leak. Starving your engine of oil will ruin it.
Low oil pressure could happen if you still have enough oil in the engine. This will either mean:
- You used the wrong viscosity oil
- Your oil pump failed
- You have a dirty or clogged oil filter
Bad Spark Plugs
While bad spark plugs are mostly connected to engine misfires, they can also cause ticking sounds just before they fail to the level of making the engine misfire. This will mostly happen when the pressure in the combustion chamber makes them vibrate in the thread ticking against the cylinder head.
Wait for the engine to cool down before removing and inspecting your plugs. You can follow this inspection process.
- Wiggle the plug and ensure it is tight enough. Loose spark plugs can make ticking sounds even if they are not misfiring.
- The spark plug could be cracked, or its thread damaged
- Overtorqued spark plugs that damaged cylinder head threads
Worn Valvetrain Components
Remember the valvetrain parts we said make noise when starved of oil? Well, they can still make ticking noises if they are worn out or not adjusted to the correct gap distances.
Tear and wear could push them out of shape and tolerance. Adjusting the rocker or installing new shims could fix the problem.
Knocking Rods
A loud metal-to-metal sound could be a sign of knocking rods. A rod knock isn’t a small problem, as it will ruin pistons and the crankshaft.
The noise will be an almost musical tick that increases frequency as you Reve up the engine – for instance, when accelerating.
Rods knock when their bearing wears out or gets damaged. The problem and its repercussions could call for a complete engine rebuild or even a whole motor replacement.
Damaged Accessories in the Engine Bay
Even though most people start thinking of the engine whenever they hear a ticking noise under the hood, sometimes, the noise could be from anything else but the engine.
There are so many accessories under your hood. These range from the AC compressor to the alternator, fan, and even vacuum pumps if your vehicle doesn’t derive vacuum from the engine manifold.
Carefully inspecting the engine bay and ruling out these components one by one will help you narrow down the problem.
Your inspection could range from closely listening in on every component to disconnecting from the serpentine belt or unplugging the power line to the fan for a moment to see if the noise goes away.
If it does, then you can rest easy. Your engine is fine, and the noise is from one of these accessories.
Bottom Line
A ticking noise from your engine bay can be annoying. Troubleshooting can even be more involving since so many things can make a ticking noise. You will need some patience and a good plan of action to filter out the most dangerous (low oil levels, low oil pressure, faulty plugs, faulty valves, and fuel injectors) before moving on to anything else.
A problematic ticking sound will always be accompanied by extra symptoms that point you in the right direction. Coupling such symptoms when diagnosing your car will prevent you from chasing a ticking noise in the injectors while the culprit is a small piece of gravel trapped somewhere under the hood.