Skip the auto shop - Our mechanics make house calls

Q: Load on truck's engine causes loud knocking noise

asked by on

When there is a load on my truck’s engine, there is a loud knocking noise. When I used a scanner, it registered a cylinder 5 misfire is detected. I have replaced the ignition coil, wires, and the plugs, but the problem still is existing. Can you tell me what is causing this knocking sound and give me advice on how to fix it?

A: Hello. It sounds like there may be a proble...

Hello. It sounds like there may be a problem with the piston or the valves in cylinder 5. Loose rod bearings to the piston can cause a knocking noise and/or a misfire condition. A worn out piston can also cause these symptoms. It is possible for a misfire to be caused by burnt valves but this will usually cause a tapping noise in the engine.

Since you have already replaced the ignition coil, wires, and spark plugs it is likely that there is an internal engine problem. In this case it may be necessary to have the engine rebuilt or replaced with a new one.

I suggest having the car looked at by a certified technician who can diagnose the noise in your engine firsthand and suggest an accurate repair from there.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: There is fluid that looks like a chocolate milkshake in the radiator

This is generally a sign of a blown cylinder head gasket. When the cylinder head gasket is compromised, this allows oil to leak into the coolant system, creating the chocolate-like substance that you see in the radiator. When this happens,...

Q: Car shaking and misfiring

Hi. The first thing to do is check the codes stored in the engine computer. If the engine is indeed misfiring, codes will be stored. The source of the misfire will need to be identified, possible faults include a failing...

Q: Car is making a knocking noise when stopping. Other mechanics say it's motor. Some say it's the piston

Unfortunately, there is no way to tell without doing some more testing. The timing and small details about the noises you are hearing may make a huge difference in diagnosing the issue. Lifters will make more of a "clicking"...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...