2011 5.4l timing chain tensioner gasket failed and....
 

A couple of weeks ago I noticed the acceleration on my 2011 Expedition (114,000 miles) was rather sluggish and then I noticed a 'tapping' from the right/passenger side of the engine. I took it to my local independent Ford guy and they diagnosed that the right side tensioner gasket had failed and this prevented the oil from pressurizing the right side valve cam/assembly (causing the lack of power). There were no engine codes nor low oil pressure warnings. There were several rocker arms flat spotted, the valve cam shaft was horked up and the total cost to replace the cam shaft, 12 lifters, 12 rockers, right hand tensioner, gaskets, oil, oil filter, 19 hours labor, etc was $2400. They said the engine internals were extremely clean (I change oil with Mobil 1 High Mileage every 4000-4500 miles and I use Motorcraft or Bosch oil filters).

They said they had never seen a tensioner gasket fail like this and that it was probably just a 'fluke'. My wallet did not appreciate this 'fluke'.

Has anyone seen a similar failure?

Thanks.

Notice the small gap in the gasket:

http://www.onewolf.org/Files/20180413_125336.jpg