Testarossa US spec clicking/tapping sound

My 88.5 US spec Testarossa developed, or I just noticed today, a tapping sound in the engine bay.

It’s had a tapping noise when cold ever since I’ve owned the car that I always attributed to the accessory belts. The noise always went away as soon as the engine warmed up. However, today the noise was present while the engine was hot, and after some rather spirited driving.

I used an automotive stethoscope to try to pinpoint the source of the noise, but I was unable to. My initial concern was the valve train but it does not appear to be originating from the area around the valve covers or heads. My suspicion is maybe an exhaust leak. There does appear to be a slight exhaust smell that present on the left side of the engine, although it’s possible the smell is coming from the tailpipes themselves. How would one properly diagnose an exhaust leak?

There are no running or drivability issues, no loss of power and idle is normal. The car is scheduled for a major service in early December. Until I get this diagnosed I will absolutely not drive the car. Here is a short video of the noise: https://youtube.com/shorts/A4omFfQQO8o?feature=shared

any ideas or suggestions?

 

Never once has a video helped at all.

Probably an exhaust leak. Put it on a hoist running and use a stethoscope with the probe removed.

 

I agree with Brian, it sounds like an exhaust leak. The rhythm of the noise matches the timing of one cylinder firing. As Rifledriver said, use a mechanic's stethesc0pe with the probe removed from the hose (I insert a long section of brake pipe with one end flared to fit into the hose). Then probe around each exhaust port/gasket/exhaust header junction. When you come to the leak, you will know it, as the sound of the exhaust leak will be very loud/evident in the stethescope.
There will also be discoloration in the area of the exhaust leak if you look closer. You will probably have to do this from under the car to pinpoint the leak.
I wouldn't worry about driving the car, as the noise goes away hot, from the exhaust manifold expanding and closing up the leak. The worst that it will do is cause the oxygen sensor to see a lean mixture (from outside air entering the exhaust) and richening up the fuel mixture a bit. As it goes away hot, the mixture will return to normal

 

I put the car up on my quickjacks and used a stethoscope as recommended. Unfortunately I was unable to locate signs of an exhaust leak. The noise appears to be strongest at the very front head on the left bank (cly 12)? I am wondering if maybe it is a loose valve seat, but if it is a valve seat wouldn't I have symptoms such as oil consumption, smoke, poor idle, power loss etc? I do not have any of that.

 

Mine was tapping when the valves needed to be reshimmed. Some of them on the passenger side were way out of tolerance. Of course it had 90k miles on it at the time.