1. At first, we suspected a faulty intake manifold gasket, but replacing them didn’t help. The intake ports were all clean, too, ruling out the intake valve guides and seals. Compression and leak-down tests both returned acceptable numbers. Hafliger felt strongly that the rings were bad in spite of our test results. "Those tests only check the top ring," he said. Oil could still be bypassing the oil control and second rings. So, we removed the engine and brought it to him.