Skip the auto shop - Our mechanics make house calls

Q: My car developed a very loud knocking sound.

asked by on

I have car that developed a loud knocking sound. I don't really know what it is, I was told it could be a rod or the rocker arm but I don't know how to get to them. Can I get to it without taking apart to much of the car?

My car has 175000 miles.
My car has an automatic transmission.

A: It is possible the valve lifters are starve...

It is possible the valve lifters are starved of oil due to a failure in the rocker arm. There are reported cases where the rocker dowel pins shear off. A direct consequence of that is oil starvation as the oil holes get covered. The rocker arms are part of the cylinder head assembly, so it is an on the vehicle repair and YourMechanic specialists, depending on your region, will be able to complete the work. Just to make sure that it is an internal engine noise, you can disconnect (briefly) the serpentine belt that drives all of the accessories and see if, by chance, the noise goes away (just in case it’s a failing alternator pulley bearing for example). It sure sounds like a valve lifter oil starvation issue though.

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: Car leak unknown

Hello. In order to pinpoint where the car is leaking radiator fluid, it would be necessary to perform a coolant system pressure test. The purpose of this test is to pinpoint exactly where the leak is located. This should be...

Q: Drive 4 miles in stop and go car will not restart....after 1 hour start, then within 2 miles stalls and will not restart.

It is possible that you have an electrical issue with your fuel or ignition system. The ignition coil could be faulty causing the spark plugs to quit firing. The electrical connection to the fuel pump could also be faulty causing...

Q: Loud humming noise

The bearing or brushes in your alternator are likely going out. You could also have another issue in your belt drive system causing the noise and lack of charging. A visual inspection of the drive system, a stethoscope to listen...

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...
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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...