Among SUVs, the Lincoln Navigator is a staple that won the hearts of people with its luxurious cockpit. Also surprisingly good gas economy for vehicles in its class. However, there are some known issues with the Lincoln Navigator 5.4 engine.
From a reliability standpoint, sentiments are mixed amongst both owners and mechanics. With some placing it in the lower thirtieth percentile and others in the top 80%. However, varied opinions view a couple of verifiable and common issues reported to have affected the 5.4L Navigator engine.
The Top Issues Plaguing the 5.4-Liter Triton V8 Lincoln Navigator Engine
The Lincoln Navigator 5.4 engine problems start with ignition assembly malfunctions.
All iterations of this motor seemed to be haunted by this issue. From the two-valve, three-valve, and the four-valve. The 5.4 triton engine had individual coils for every cylinder located atop the plugs. This is known as the coil-on plug architecture. It was an innovative effort but was vulnerable to overheating. Complications start when the covers on top of the coil boot corrode and leave the spark to contact the plug-well instead of the spark plug.
Plugs eventually often fail due to fluid penetration too. To solve this issue, your mechanic will make a diagnosis to see which cylinders are misfiring and replace the plugs and coils appropriately.
Fluid leaks into the coil boot
Liquids such as oil and lubricant can sip onto the boot and deteriorate coil performance drastically. Upon failure, you may observe cylinder misfires particularly during acceleration and between 50 and 60 miles per hour in overdrive. Often misdiagnosed as transmission failure, you will also experience some jerking. Preventative maintenance for this is to replace plugs every 50, 000 to 75, 000 miles.
Fuel pump failures
Mostly prevalent is the three-valve application that utilizes a module to regulate fuel hose pressure via bore modulation of the pump. Damage from rust is what mostly causes this unit to malfunction on the Lincoln Navigator 5.4 engine.
In earlier trucks, the aluminum module was directly placed on the steel frame. Corrosion would take over, eating a hole through the aluminum, allowing water and environmental components to shorten the electronics. An error code of P1233 is indicative of this kind of malfunction. In later models, the pump driver was modified and they released a replacement version. The main improvement was additional apparatus to shield the module from the frame.
The 2008 Lincoln Navigator engine was prone to producing burnt coolant odors and overheating with no observable signs of leaks. The 2008 Lincoln Navigator was noticeable for exhibiting symptoms of coolant leaks like the above mentioned with absolutely no signs of a spill. This is because of the unique design of the vehicle.
The leak is so deep inside the unit that you cannot observe it from above. Located under the intake manifold, you only notice coolant on the ground when a lot of time has passed. Coolant spills from the heater tube, a pipe that directs coolant to flow between the heater core and the water pump.
Issues From Leaking Fluids
The leaking fluid will burn on the engine block emitting a flowery smell that is distinguishably coolant. To repair this, you will need to remove the intake manifold and water pump to gain access to the heater tube and connector. Depending on your model, you will replace the connector and/or a couple of o-rings.
The details of the methodologies associated with increasing the transmission’s lifespan in general and addressing the common problems before they make themselves known.
The 2011 Lincoln Navigator 5.4 engine problems- 2011 Lincoln Navigator was especially troubled by fluid leaks originating from the bell housing of the 6R80 transmission. Owners report intermittent leaks, sometimes going a fortnight without any spillage, then a 12-inch diameter pool would appear under the vehicle in a few hours. Most of these leaks appear to be associated with the housing and the case connector. This year, a technical service bulletin was issued for this transmission. A common solution for this problem was to replace the connector and monitor for any more leaks.
High Pressure Build-Up
If you experience more leaks, any person familiar with the 6R80 will tell you that you might have pressure build-up in your transmission. A plugged-up transmission vent will most likely be the main cause of your problems. Remove the cap for the vent to expose the usually red valve laced there to stop water from entering.
Even the slightest misalignment causes this valve to hold back enough pressure to cause multiple leaks in your transmission. Remove and replace the valve and observe for any more leaks periodically.
Preventative maintenance here would be to check the valve at determined intervals. When removing the valve, if you get a gust of pressurized air leaving the transmission housing, then you most likely need to replace the valve before any leaks spring up.
Hesitation in forwarding or reverse gears after a cold start. 5.4 engine problems sometimes originated from the transmission. Especially with the ’90 to ’10 Lincoln model, owners had a hard time getting started in the cold seasons.
To solve this, you need to replace your fore/front pump adaptor seal and separator plate.
For preventative maintenance, periodically check the shape of your separator plate and also clean the main oil pressure regulator valve along with its pit.
The ’11 to ’13 Lincoln Navigator was among the vehicles called back due to a faulty 6R80 transmission. Others included the 2011 to 2013 Ford F150, Expedition, and Mustang, all from the same years. A defective transmission range sensor caused several problems when the reverse position was engaged. Some were failure to engage reverse, the electronic gear selection display would not show the reverse gear, reverse lights would not operate, and periodical failure of the rear camera.
The solution for this is also preventative maintenance, replacing the 6R80 transmission’s lead frame assembly, which incorporates the TRS sensor.