Here's why this is likely and what it means:
* Connecting Rod Bearing Failure: This is the most likely culprit given the symptoms. Connecting rod bearings lubricate the crankshaft journals where the connecting rods attach. Failure leads to the rod moving excessively, causing the knocking/tapping sound and potentially striking the valve cover. Low oil pressure would usually accompany this, but sometimes the pressure gauge can remain high initially.
* Other Possibilities (less likely given the symptoms): While less probable given the "rod hitting the valve cover" description, other possibilities include:
* Severe Piston Damage: A severely damaged piston could also create a knocking sound, but the valve cover contact points to rod bearing failure more strongly.
* Valvetrain Issues: Extremely severe valve train problems *could* theoretically cause a tapping sound, but usually wouldn't lead to a loss of power this severe.
What NOT to do:
* Do not continue driving the car. Further damage is almost certain to occur, potentially causing catastrophic engine failure. Driving it could lead to significant internal damage, making repairs much more costly or even impossible.
What you SHOULD do:
* Have the car towed to a qualified mechanic: A visual inspection and possibly a compression test will confirm the diagnosis. Unfortunately, given the symptoms, it's highly likely that a major engine overhaul or replacement will be required.
* Prepare for a significant repair cost: This type of damage is expensive to fix. Depending on the extent of the damage, it might be more economical to replace the engine.
In short, this sounds like a very serious engine problem. Immediate action is required to prevent further damage. Don't attempt any DIY repairs without significant engine repair experience, as you risk further injury or damage.
