Ls430 Engine Noise - Any Ideas?

[AngelEyes]

Hi All,

I recently bought an LS430 with 185,000 ks on the clock. During cold starts the engine makes a kind of squeak/tappet noise which goes away after the engine warms up about 3-4 minutes later. If I start the car 8 hours later it doesn't make the sound, so I'd need to leave it with a mechanic over night to get an understanding of what it could be. If anyone here with experience would care to listen to the audio file I've attached to dropbox in the link below, I'd appreciate that very much. I've also attached a picture and circled the area where the sound appears to be coming from.

My best guess so far is hydraulic lifters, or a squeaking belt or worse an engine bearing of some sort.

As you can tell I'm not overly savy when it comes to engines, especially one as complicated as this, but I'm a keen learner I guess.

https://www.dropbox.com/sh/wz0am4kv8ov78ej/AADJuzISTQ_dZGaj0pYrbWcoa?dl=0

Cheers.