Hereā€™s some diagnosis fun for Oppo thisĀ morning. The Defender has developed a rev dependant (and quite loud) chirpĀ coming from somewhere inside the engine bay. It starts and maintains itself from low to mid revs, and completely disappears from mid to high revs. The aux belt and all pulleys are in good condition, but there is slight play in the tensioner pulley, maybe 2mm play front to back. As this thing ex-MoD, theĀ timing belt is on an unknown schedule and completely unknown mileage. As it happens in all gears, Iā€™m negating anything after the clutch, so must be between clutch andĀ engine, or engine and belts. Any thoughts?