I would start by referencing the following article by a respected firm that developed a solution for what has plagued the V8 water cooled Porsche motor design from 2004-2009.

https://lnengineering.com/products/watercooled-porsche-cylinders-sleeves-and-pistons/bore-scoring.html

Through litigation and victim blaming, Volkswagen A.G. has kept what appears to be a fairly serious flaw from gaining any traction the way that their use of a poorly designed intermediate shaft bearing caused numerous lawsuits until they finally settled for affected owners acknowledging the poor design.

In the case of the Porsche designed V8 block affecting Cayenne V8s from 2004-2009 and early Porsche Panamera Turbos, poor QC from certain subcontractors in the manufacturing and sleeving of cylinders and piston assembles has led to premature wear of the cylinder walls (known as bore scoring) which, in turn, leads to eventual engine failure. Affecting vehicles with mileage as low as 50,000 to vehicles like mine with 123,000, cars can have been serviced by independents, or in the case of my own vehicle almost its entire life by Porsche A.G. dealerships and still develop this pitting in the cylinder walls.

Surveys conducted of groups in the several hundreds of Cayenne owners have shown a projected failure/defect rate of between 8-16% of all V8 engines, Turbo or otherwise. Many were covered under warranty, but more still are now falling outside that sphere of protection. Usage of friction modifiers along with more frequent than recommended oil changes are currently the best measure of protection, as are identifiable engines that were not produced by these agencies as identified in a 2014 TSB internal to Porsche identifying engines that beginning in late 2008 were altered in their manufacturing process to address this known issue.

Currently the only -surefire- way to address this issue (and hence why the price for repair is as high as it is, though we'll touch on that later) is to seek out either a completely new motor from V.A.G. or source an aftermarket block and piston assembly designed to prevent this wear and mate it with an unaffected valve train (assuming metal and contaminants haven't scored any other surfaces in the process. ) Total cost for this 'correct' solution with shop rates at reasonable levels can top 13 to $14,000. The less ideal, although only method I can afford, is to source a lower mileage motor from a salvage yard, ensure that no signs of bore scoring exist, and have it installed. This, in turn, is where my dollar figure of approximately $8,000 in parts and labor comes into play. Most sell the cars off, or trade them in to dealers. The few that are stuck will part of their vehicles absorbing the loss of the motor in silent indignation.

Why does the ticking noise matter? Scored cylinders can lead to total loss of compression, drastic increase in oil consumption, the sound (piston slap) is extreme force against the cylinder walls, eventually mix of oil, gasoline, exhaust gases and total engine destruction. If you have bore scoring, this -will- happen. Even if you follow the recommended service intervals to the letter, you are still at risk from a -known- defect. From a company that willingly admitted to cheating emissions control systems to actively hide this fact and launch litigation against parties affected is the worst a business has to offer in order to maximize profits.

I suspect they think all their owners would just shrug their shoulders at dropping 15,000 as mere nickels and dimes. I can't afford to. So while this probably looks like an ad to sell products (see above link) google the terms 'Bore-scoring' and 'Cayenne' and you'll find video after video where this is apparent. Even a recent high profile 'Bring a Trailer' auction showed that the rarest of Cayennes are susceptible. The problem is covered in greater depth on multiple Porsche forums, and I suggest researching before you buy into the vehicle. This will be my third, and frankly, final Porsche as I'm not their target audience, and never will be. Sometimes you cannot hide from the things you have done.