Skip the auto shop - Our mechanics make house calls

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.

A: Most likely, the knocking under load you he...

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. 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 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・Save up to 30%

Get a quote

What others are asking

Q: Rear differential humming

Hi there. A humming noise usually indicates a worn pinion bearing or an incorrect backlash setting on the rear differential between the ring and pinion gear. Sometimes, if the pinion bearing develops play due to wear, the pinion gear will...

Q: Fan loose, water pump noise, truck heats quickly - 1992 Chevrolet C3500

This could be either the engine cooling fan clutch or the water pump. Since you mention faster warm-up, it may more likely be the fan clutch. A YourMechanic professional can help diagnose and replace either the cooling fan clutch or...

Q: Loud humming noise

Hello. There could be a problem with the alternator not charging properly, causing low battery voltage. This could cause electrical components to come on and off when they shouldn’t. The alternator could be making the humming noise you hear if...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
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...