We were able to identify engine blow-by as a primary factor affecting camshaft wear in gasoline engines. Using a 2.3-liter overhead-camshaft engine, we isolated the valve-train oil from the crankcase oil and its blow-by using a separated oil sump. We find that:

– with engine blow-by, the camshaft wear was high.

– without blow-by, the camshaft wear was low.

– with blow-by piped into the isolated camshaft sump, the wear was high again.