Hi All - I have viewed a number of tapping/clicking/rattling/ticking threads on ClubLexus but haven't found a thread that closely matches what I'm experiencing with my 2008 LS460, although this one comes closest: https://www.clublexus.com/forums/ls-4th-gen-2007-2017/854315-audible-clicking-ticking-while-accelerating.html

Here's what I observe:

Tapping has only begun recently (approximately last 10k miles of 52k miles driven)

Tapping doesn't occur every time I drive the car.

Tapping speed/cadence/tempo varies with speed. Makes no difference whether accelerating (under load, foot on gas) or coasting (foot off gas).

However, it disappears as soon as brakes are applied, at any speed.

Makes no difference whether engine is cold or up to temperature.

No sound at idle or start-up.

Originates in front-right portion of car (forward of passenger seat). My passenger can often hear it at higher speeds from that seat, whereas it's drowned out by road noise from the driver's seat.

Any ideas would be appreciated! My mechanic recommended a 109 treatment at the next oil change but otherwise seemed unconcerned (https://www.bgprod.com/catalog/engine/bg-epr-engine-performance-restoration/). I've read about noise from heat shields, piston slap, fuel pumps, fuel injector rails, leaking exhausts, even loose brake pads, and I suppose it could be any of these things, but I know it's not the normal direct injection sound, which I'm familiar with.

 

Brake dependent [engine] tapping? So does it tap at idle stationery???

 

No tap at idle or when stationary. The noise is coming from the front right portion of the car, but not necessarily the engine. Applying the brake silences it every time. The front pads and discs were replaced about 10k miles ago (I can't remember whether I heard the tapping before that service)

 

Well, it's not engine then. If it's loud enough so it can be heard inside - my suspects would be axle (cv's), improper brake mounting/hardware installation, worn suspension components in that order. That 'service' is sus. Probably that's when it's started then progressed. Probably. Not 100%.
Is it AWD or RWD? Moar data, please.

 

RWD. I agree the timing is suggestive (I only wish I could say for sure whether I heard the tick before the brake job or not). I haven't had the notorious brake actuators replaced (https://www.clublexus.com/forums/hyb...port-card.html)

 

If you're able - jack the offending side's wheel, look around, take a lot of pics. No, it's not your actuator (99%, not yet at least). RWD = even less failure points! There's no front axles, front drivetrain etc. It's something trivial like rubbing pad stuck sideways or something.

 

While checking front brakes, check front bearings as those do go out.

 

Air shock pump is located behind right front bumper.

 

It usually only pumps when stationery (or below 20mph I forgot). Wheel bearing is very plausible, but my bet is still improper mounting hardware/install.