Thanks for coming to my site. In case we haven’t met yet, I’m Kevin and I just love passing on my 30 + years of experience repairing and maintaining cars.
I’ve made this site for non-technical drivers who are experiencing problems with their cars.
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Published date: November 1, 2021
Updated date: February 27, 2024
Reading time: 8 min
This article was fact checked
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Before we get into the detail, briefly, your car sounds like a motorcycle because either of these issues is present.
Serpentine Belt is Loose or Worn
The Exhaust Has A Leak
PCV Valve Loose
Engine Needs Attention
Transmission Problems
All of the above can be the reasons for the noise, but some are more common causes than others.
Why Does My Car Sounds Like a Motorcycle When I Accelerate?
Exhaust Problems
As you accelerate, your engine works harder and creates more exhaust gases. The extra pressure created may cause exhaust gases to force their way out of joints or holes within your exhaust system.
This noise is often described as sounding like a card in the spokes of a bicycle.
If you pull over and look underneath your car with the engine running, you may see gases escaping along the length of the system. If you smell exhaust gas at the top end of your car, this is a sure sign of a leak somewhere.
Cost
The repair costs vary considerably and depend on whether there’s a hole in your exhaust or a broken seal. Exhaust tape is often used to wrap around any holes.
If the exhaust is beyond repair, you can often replace the section rather than the whole system.
Engine Issue
It might be an engine issue if your car sounds like a motorcycle upon acceleration. The valves within the engine may cause this noise.
Often the cheaper cause is the oil level is low or old and needs replacing.
Cost
This could be as cheap as changing your oil and oil filter or as expensive as having the head of the engine removed, and remedial work carried out inside.
Fortunately, it’s almost always the former, but if you suspect the engine may need attention, you should stop driving immediately. Continued use will cause further damage to the engine and the expense that goes with it.
Transmission
Your cacar’sransmission is a complicated piece of machinery. It also needs to be lubricated correctly. If the fluid is low or old, this can cause a rattling, often described as a motorcycle noise.
Check your transmission fluid reservoir under the hood. It should be red, but it’s more likely to be dark brown if it’s old. If the transmission fluid is topped up and red, you might have a more serious problem with the transmission.
Cost
Transmission fluid is cheap and easy to replace. However, any transmission repairs could end up being extremely expensive. The parts are relatively cheap compared to the high costs of labor.
Car Sounds Like Motorcycle At Cold Start
Exhaust Manifold Gasket
Although the noise is often attributed to the engine, it is more likely to be the exhaust system. Even if you hear the noise at the front of the car, don’t be fooled into thinking it’s the engine straight away.
The exhaust has a manifold that is right close to the engine. When this becomes loose or the gasket’s brittle, it can allow the exhaust gases to escape. Once warmed up, the metal expands slightly and reseals the gap.
You can find it just after the cylinder head, where it joins the exhaust. The exhaust gasket seals and pressurizes the system. Any loss in pressure can result in sluggish performance.
If your car, when warm, runs better, than an exhaust gasket is the likely culprit.
Cost
This is a nice cheap fix. Expect to pay $20 for the exhaust manifold gasket and an additional hour’s worth of labor to have it fitted.
If the sound persists when the engine is warm, pay attention to the serpentine belt, as discussed below.
Why Does My Car Sound Like a Motorcycle When Idling?
If your car sounds like a motorcycle when it is cold and idling, it could well be the exhaust manifold gasket, as discussed.
Serpentine belt
However, if the sounds persist when your engine is up to normal operating temperature, open the hood and listen closely to the serpentine belt. This belt runs from the engine and powers the alternator and many other electrical components.
The serpentine belt normally makes a slapping noise when worn or loose. Still, if it is coming into contact with a component because the tensioner for the idler pulley is not working properly, it could cause a motorcycle noise.
Cost
Serpentine belts of a cheap fix. They should last between 60000 and 100000 miles but often fail sooner.
Expect to pay between $30 and $70 for a new belt and an additional $200 for labor.
PCV Valve
A PCV valve controls the number of emissions going into the engine and can work loose. This valve is often located on the engine block at the back and is often covered with a rubber grommet. When loose, this has often been described as a motorcycle noise too.
Cost
A PCV valve is cheap and costs between $10 and $20, depending on the make and model of your car. Expect to pay between $50 and $100 in labor for fitting.
Conclusion
There are five main causes of the motorcycle sound your car makes. Many are cheap fixes, such as topping up or changing the oil or transmission fluid.
PCV valves are quite simple to replace, as is a serpentine belt if you are a basic DIY mechanic with a fairly well-equipped toolbox.
The exhaust system is the most likely reason for the noise, especially if you hear it more loudly when accelerating.
The two remaining potential faults are more expensive but the least likely. Any repair that involves complicated mechanical parts, such as your engine or transmission, will always be expensive.
Thanks for coming to my site. In case we haven’t met yet, I’m Kevin and I just love passing on my 30 + years of experience repairing and maintaining cars.
I’ve made this site for non-technical drivers who are experiencing problems with their cars.
