2005–2010 Lincoln Navigator / Mark LT: known reliability problem

The problem

5.4L 3-valve Triton V8 — spark-plug breakage/blowout and cam-phaser rattle.

Vehicles affected

Lincoln — Navigator, Mark LT, model years 2005–2010. Adjacent years and trims with different engines are generally not affected; the exact engine/transmission in the specific car is what matters.

What it means for a buyer

This is a real, documented pattern — but often preventable or already addressed. It is a reason to inspect harder and negotiate, not necessarily to walk away: a car with records showing the issue was serviced can still be a good buy. For context, a Lincoln averages about $879/year in maintenance and typically retains roughly 44% of its value after five years.

Considering one anyway? Do this

• Ask directly whether the affected component was repaired/replaced, and get the paperwork.
• Get a pre-purchase inspection from an independent mechanic and mention this exact issue.
• Check open recalls by VIN at nhtsa.gov/recalls.
• Pull the free government title history (salvage/flood/odometer) at the NMVTIS portal.
• Price it against unaffected rivals — this issue is negotiating leverage.