camry began to make a roaring noise yesterday, as if something was wrong with the engine, when i accelerated onto the interstate. the noise continued and it became harder to accelerate; pushing the gas pedal only made the engine roar louder. when i made it back to the apt and lifted the hood, the oil cap had popped off and oil was all over the back of the engine and surrounding parts. Any thoughts on what might cause this?

 

Who last added oil to the engine or changed it? Was the cap fully on? If the cap came off when driving you will have oil every where.

If you went to a oil change place it is possible they failed to fully install the cap.

Check the cap threads for damage. Typically there is a baffle plate below the filler point on the valve cover. This keeps the oil from directly splashing on the cap.. Make sure if the car has one it is still there.

If everything looks OK, refill with oil and install the cap. Make sure it snugs down. Start engine and determine if the noise is gone. It could have been just engine noise with the cap off.

If the cap was on snug before it came off when driving, check out the PCV valve and hose for plugging. This could allow pressure to build up in the engine. Make sure the engine was not overfilled with oil.

Suppose excessive blow by could cause crankcase pressure build up. How was the oil consumption before this, any damaged pistons rings, etc.

If the low oil pressure light did not come on the engine is most likely OK and was not damaged from lack of oil. Engines have been totaled due to all the oil blowing out the filler hole for lack of a cap.