I am facing strange rattle sound on idle. Please see video. Sometimes that sound become too louder that everyone can notice it from way too long. When i put car in parking or change gear lever to D, that sound stops. I think it is knocking of engine but not sure. Note: using hi-octain reduce that sound but not completely turn it off. And this sound become more louder when engine is charging batteries. Can anybody suggest how to get rid of this?
It sounds bad. If it is engine it is the top end. Probably. Is the oil level OK? The fact that octane of fuel reduces it is odd and suggests a problem with air fuel ratio somewhere for some reason. Which could include random things like valves not fully opening or closing. I would be tempted to remove the valve cover and see what, is going on with the timing chain, cams, lifters, valves. That sound is loud enough that something is close to catastrophic failure and early intervention could save the car. Finally, is the gearbox oil ok and did the car have issues with charging the battery as might happen if something is dodgy in the transmission? I would be tempted to do engine oil change and use a magnet for metal fragments, then transmission. But check the top, under the valve cover, and the timing chain first...
