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Whenever our car makes any noise we don't recognise, we can feel that little creep of dread rise up within us. When you hear a knocking noise when driving, it's typically a sign of worn, loose, or unlubricated components that need professional attention to prevent safety risks or offset expensive repairs. The key is all about acting quickly so we can stop these minor issues from escalating into major breakdowns!
Is a Knocking Noise Serious?
A knocking sound is your car's way of telling you a component is moving in a way it should not. Sometimes it can be as simple as a loose exhaust bracket, but it could indicate engine, suspension, brake, or wheel problems that affect how safely the car drives.
If the noise is loud, metallic, gets worse quickly, or your warning lights start flashing like it's Christmas, or you get a lot of vibrations or a burning smell, you need to reduce your speed and get the car inspected as soon as possible.
The Common Causes Of A Knocking Noise When Driving
Low Engine Oil Levels
Low or contaminated engine oil reduces lubrication between the moving parts, like the pistons and bearings, leading to metal-on-metal friction, producing a ticking or knocking sound, which you would notice at idle or low revs. Oil leaks from seals or gaskets can starve the engine, worsening over the miles driven without any major checks. Dirty or overdue oil loses viscosity from the heat cycles, sludge build-up, and contaminants, which fail to cushion components effectively. What's more, infrequent oil changes allow breakdown products to abrade the internals, which then amplifies the noise.
Worn Suspension Parts
Suspension components like ball joints, control arms, shock absorbers, and bushings will degrade over time due to various reasons like potholes, mileage, and the weather, causing knocks over bumps as play develops in joints and mountings, which doesn't just create noise, but also can result in uneven tyre wear, pulling, and longer braking distances because wheels are losing firm road contact.
Loose Exhaust Components
Exhaust systems suffer rust because of condensation, road spray, and winter gritting, which can then loosen the brackets, pipes, silencers, or heat shields, resulting in rattling, particularly over rough surfaces. While these issues can be annoying initially, detached parts can eventually drag, spark, or obstruct the road, posing hazards to other drivers.
Wheel or Tyre Issues
Issues like loose wheel nuts, failing wheel bearings, or damaged tyres can generate rhythmic knocking synced to the road speed as the wheels wobble or grind. This needs urgent attention, as any severe bearing failure or detachment can cause loss of control at high speeds. This is where regular torque checks, post-tyre work, and general visual inspections can catch these early.
Brake System Issues
Loose callipers, worn pads rattling, or warped discs can create clunks during braking, cornering, or take off as components shift abnormally under force. Any noise in the brakes is going to compromise the stopping power, and you need to prioritise this. They could be simple fixes like increasing pad thickness, disc runout, or improving the hydraulic integrity.
CV Joints and Drive Shafts
Constant Velocity (CV) joints in drive shafts wear from split boots, letting grease out and dirt in, which causes clicks on turns or knocks on acceleration or deceleration. This is an issue common in Front Wheel Drive cars and can leave you stranded roadside if you're not careful.
Engine Detonation Knock
Combustion knock, or pinging, arises from low octane fuel igniting prematurely or timing or sensor faults, which you will hear as metallic rattling under loads like hills or when you're overtaking, and the prolonged exposure is going to erode the pistons and rings.
When Should You Stop Driving?
You should stop driving and seek recovery if you notice any of the following:
- Loud metallic knocking from the engine.
- Knocking every time you brake.
- Strong vibrations through the steering wheel or body.
- Burning smells, smoke, or dashboard warning lights.
How Longmynd Service Station Can Help
If you are hearing a knocking noise when driving, we are always here to help. If you need any type of support, we can do the following:
- Carry out a road test and full visual inspection to pinpoint where the noise is coming from.
- Check engine oil level and condition, and scan for any engine management faults.
- Inspect suspension, steering, brakes, wheels, tyres, and exhaust for wear, looseness, or damage.
- Advise you clearly on what needs doing now for safety, what can be monitored, and also provide a no obligation quote for any work.
Book An Inspection For Knocking Noises
If you hear a noise when driving, don't wait for it to get worse; contact Longmynd Service Station to book a diagnostic check or speak to a member of our team about the noise you're hearing. We will check your vehicle, explain our findings simply, and get you back on the road in no time.