I have a strange sound coming from the engine in my '96 2.7 5 speed.

It has been there for quite some time. It's only noticeable at some angles, mostly from next to the front RH door. If I lift the hood and listen, I can hardly catch it.

It's a very light tick, just like normal injector tick, but atouch louder than the others. The injectors were replaced about 25,000 km ago with brand new OEM. The frequency of the tick is also far slower than the injectors (maybe 1/4). I only ever hear it when the engine is idling. Otherwise, the engine is perfect - great fuel economy, no oil use, starts in the button. Valve clearances are perfect, plugs, leads, distributor cap and rotor relatively new and allproperly fitted.

Because the frequency is so slow, I really struggle to imagine what it could be - it cannot be an injector, piston pin bearing or balance shaft as this would tick at the same frequency as the injector, which I can hear using a screwdriver as a stethoscope. I think it's also too slow to be a valve.

It's definitely not coming from the power steering pump, alternator or AC compressor. It's not coming from the clutch housing and I can still hear it when I press the clutch in.

Has anyone else had a noise like this?

Thanks

EO