Q: Car Knocking at 1600- 2100 RPM loaded condition

asked by on

Car Knocking at 1600- 2100 RPM loaded condition. The engine is after a top overhaul.

My car has 12000 miles.
My car has an automatic transmission.

Most likely, the knocking under load you hear is worn connecting rod bearings. The top-end overhaul (including the valve job?) has increased cylinder pressure during the power stroke (assuming the valves were not sealing perfectly), exaggerating a "knock" that probably wasn’t as easy to detect before.

If confirmed, this repair will require replacement of rod and main bearings, possible machine work on the crankshaft, new oil pump, new rings, etc. - an expensive repair. To avoid unnecessary repairs, I suggest having one of our certified technicians diagnose the noise from your engine, get an accurate assessment of damage and cost estimate for repairs. YourMechanic.com can dispatch a mobile, professional mechanic to your location for this repair.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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!
  1. Home
  2. Questions
  3. Car Knocking at 1600- 2100 RPM loaded condition

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 not accelerating seems like brakes are holding car from moving

Hi Yashira. Thanks for contacting us today. There could be multiple issues that are causing your acceleration problems. Obviously, if the brakes were recently replaced, it is likely that they are sticking. This could be due to a malfunctioning caliper...

Q: Minivan rattles and steering wheel vibrates

Steering wheel vibration during turns might be an outer constant velocity joint. The mechanic can check general condition of the engine, even if the engine noises are not present when the vehicle is checked. Check aftermarket automotive suppliers for non-factory...

Q: Opinion on GM's 4.3-liter Vortec engines

With the overall vehicle, it is a coincidence for your father. A lot of times, the vehicles fall apart. The engine themselves are actually decent engines. They are strong engines, those 4.3-liters. But the Vortec fuel injection system on them...

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...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...