Q: Car Knocking at 1600- 2100 RPM loaded condition

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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.

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