As I stated in a couple of previous posts, I just bought a 2004 3.0 Edge automatic. After reading through numerous posts, it seems the cam sync is destined to fail at some point. Right now I don't hear the noises people talk about when it is going bad.

Having said that, if it does go bad, will I get any kind of warning other than noise? Will the oil pressure light come on? Last thing I want to do is lock up the engine. Is it something I should just go ahead and replace as preventative maintenance? It seems to be a fairly easy job. I have 121k miles on it. I just bought it this past weekend and have no records on it, so I have no idea if its been done or not.

 

Two reasons I have found why they fail :
1- faulty gear composition
2- Lack of proper lubrication.

# 2 seems to be the most prevalent .
The unit is only "splash" lubricated via a ~2mm (<1/16 " ) hole just above the lower bearing. As the bearing wears , the contact between the camshaft gear (which drives it ) and the syncro gear decreases . This leads to the teeth on the syncro gear to fail.

 

I think the main thing is to keep up on your oil changes and watch for the squeek and a sudden loss of oil pressure. If you loose oil pressure shut it off immediately!