I bought a 2005 Excursion last year with the V10. At 115,000 miles I had to get the engine replaced because I was an idiot. But I digress...

The engine was a remanufactured unit installed by a local mechanic that I trust. I changed the oil as required at 500 miles and used Motorcraft 5w-20 semi with the FL-820S filter. At about 800 miles on the oil change I started to hear a tick which I thought was an exhaust leak. I noticed that as the engine warmed up the noise became louder and was more noticeable on decel, but still constant throughout the power band. I took it in and they couldn't hear anything.

At about 3,500 miles on the oil (yes it should have been 3000 miles for a change but I travel a lot and my wife drives the rig) my wife said she could hear a noise. I drove it and the ticking is now noticeably louder. I was unable to change the oil until about 4,000 miles. When I did, I put the rig up on my dad's hoist to check for exhaust leaks first. I could not find any sign of a leak. I put it back down and put a stethoscope on the valve covers. While the driver side was just about silent, the passenger side had noticeable mechanical noise. I changed the oil to see what difference it would make and the noise went away by about 90%. Again, as the oil warmed the noise got somewhat louder but not nearly as loud as before changing the oil.

Having ruled out an exhaust leak since the noise abated with an oil change, I took it in. Here's where things get fun. He called the reman place and the guy there said it's "normal". He said it will run like that forever and to put in half a quart of Hyperlube. Needless to say when I heard that I was absolutely dumbstruck. I called the reman place myself and talked to a different guy who was absolutely shocked that someone would say that. I've now got it scheduled for an appointment to get the valve cover off and inspected. Although it could be a few things, my question here is do the lash adjusters have an issue with collapsing? Anything else the mechanic should be looking at? Honestly I'm having doubts now about this guy since he went with the Hyperlube solution.

 

Because it's an Excursion you have a 2-valve V10. There can always be issues with valve train on anything as complex as an OHC, but this sounds unusual especially when there's a huge difference in the amount of noise between one valve cover and the other. There's even a balance shaft in the driver's side head, so you might hear MORE noise from the drivers when everything is normal.

Definitely get it looked at.