Well it looks like I will finally get a chance to work on the noise coming from engine in my EX. Before I start is there anyone out there that can provide some info? I've read some of the forums that talk about the exhaust bolts breaking. I looked for that and didn't see any broken or missing bolts. Where are the bolts normally broken?
Is the V10, 6.8L an interference or non-interference engine? I had a mechanic come by and he thinks the noise is in the valve train, possibly broken timing chain, one side of the double link chain broken?
I would greatly appreciate any feedback!

 

Check belt tensioner bearing first.
Milage on the engine?

 

There's a little over 200K miles. The noise has a fast frequency, the engine has lost power, skips, etc. It's not loud enough to be a rod and too fast a frequency. In fact the frequency is probably too fast for a single lifter or valve. My first thoughts were the oil is plugged somewhere and none of the lifters are getting oil, so all were making noises on that side of the engine.
Thanks for the reply. If you see similar post, it's because I kept posting, getting error messages, and could not find the post. Anyhow, again thanks.
Still trying to find out if the valves could get damaged if the engine has jumped timing.
Thanks!

 

Make sure your AC is off when you are listening. I had the AC running on mine and got this slight ticking. I thought one of my spark plugs was going to shoot out. Then I turned the AC off and the sound went away. Turn it back on and I hear it again.

 

I have checked with the air on and off, changed oil filter, changed oil and filter (again), and checked for loose spark plugs. None of this has changed the noise. I also noticed that I didn't have power brakes when I move the Excursion in the yard. It was idleing really rough, but it made me think that I'm not getting vacuum to the brake booster. Thinking that maybe the timing chain has jumped causing improper timing of valve opening, thus a lack of vacuum to the booster?
What I'm hoping is that the valves have not crashed with the pistons, if the problem is in the valve train.
Appreciate the feedback.
Thanks!

 

Sorry to hear about your problem, hope this helps:

The 6.8 is an interference engine, and if I remember right there is very little tolerance for any valve train slop so if your engine skipped timing, you would probably have much bigger problems by now.
If you want to inspect your heads to verify that everything is oiling correctly you can remove the valve covers and run your engine the ford service manual says that if you keep the engine speed under 1200 RPM, no oil will splash out.

Also, have your idle air control valve checked out. It might be causing your performance and vacuum problems.

 

Maybe chain tensioner (slider) on one side is worn down,chain will get loose a bit and might delay timing. Not sure if that much dough . Jumped chain would probably do more damage all ready ?
I would start with pressure test on that side.
Let us know.

 

Just pulled the valve cover off the driver's side (easiest one). Turned over the engine and did not see any damage to the timing chain. Going for the other side, but it'll have to wait until next weekend. It's hot outside!
Hopefully, I'll find the problem. I'll keep reading these post. If someone has any good ideas, let me know!
Thanks for your replies!

 

If you want to post a picture of the head I could look at it and tell you if I see anything unusual in the valvetrain.

 

It will be next weekend, but I'll either post pics and/or tell you what I found. Thanks for the interest. Hope to from everyone soon.
Thanks!