Skip the auto shop - Our mechanics make house calls

Q: Knocking noise under hood

asked by on

When the car cranks and while running, there is a knocking noise that comes from under the hood.

My car has 100000 miles.
My car has an automatic transmission.

Without actually hearing the noise, it is difficult to determine the exact cause of your concern. It could be low oil pressure, valve adjustment, bearing failure, etc. I suggest having a certified technician, like one from YourMechanic, determine the exact cause the noise.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Low oil

Well, I'm not sure if your motor is completely messed up, but running with low oil for such a long time is never a good thing. When the valve starts to chatter, they are not properly lubricated, and it's due...

Q: When turning off car, windows open, car unlocks, headlights turn on

The totally integrated power module on these cars have been known to cause various intermittent problems. Sometimes these modules are reprogrammed to fix issues with them and other times the module has to be replaced. You can try to have...

Q: Wrench light and engine light on

Generally, the check engine light comes on when something fairly serious is going on with the vehicle. This can happen for many different reasons such as a faulty mass air flow sensor, a faulty O2 sensor, a bad catalytic converter,...

Related articles

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...