My friend has a 92 Prelude Si (H23) and its making a sound similar to marbles in a can. When he last drove it (about 2 months ago) it just locked up on him while he was driving down the road... he had it towed to his house. When I went over to look at it, it started right up with the noise that he said it started making before it quit running... we changed the oil and took off the oil pan and there was no metal in it. Now we have the valve cover, cam shafts, and rocker arms... all the valves seem to be moving and tightly closed, I'm really lost about where to go with this... suggestions would be greatly appreciated. thanks

 

Rod knock maybe.

 

or hopefully just a valve adjustment is needed?

 

Pistons hitting valves, probably the timing belt is loose and skipped a tooth on the cam sprockets.