Skip the auto shop - Our mechanics make house calls

Q: Knocking sound when idling or stopped 1993 Chevrolet Lumina APV

asked by on

There is a rhythmic knocking sound coming from the left side of the engine (facing the engine from the front) near the serpentine belt. On the road you can't really hear it, it gets really loud when idling at a light. Then in park and running it's still there just not as loud.

My car has 230000 miles.
My car has an automatic transmission.

A: Hello - the rhythmic knocking you hear coul...

Hello - the rhythmic knocking you hear could be something driven by the serpentine belt (i.e. AC compressor) or the belt itself. It is also possible that this an internal noise - like the timing chain, which is immediately behind the serpentine belt on the engine. Removing the serpentine belt, then starting the engine for 20-30 seconds won’t harm the engine, but would narrow the problem to inside the engine or something belt-driven. I would recommend getting this checked out soon, as additional damage may be occurring while you drive further. A mobile, professional mechanic, such as one from YourMechanic, will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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: Starting issue

It definitely sounds like you may have a fuel supply issue. Although it is unlikely that you may have received a faulty fuel pressure regulator when replacing it, this is not unheard of. Just for good measure, I would suggest...

Q: What Causes Engine Knocking?

The engine has many moving parts that all work together to form the internal combustion engine. The engine requires a good lubrication source and a good cooling source for it to continue to work properly. The internal moving parts are...

Q: Truck running hot. Already changed water pump, thermostat, and heater hose. No water in my oil. Still running hot

You will need to have your cooling fan clutch checked for lock up. If the clutch is replaced from lack of lock up when it gets hot then have the radiator checked for coolant flow through all the passages. ...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.