2018 Lincoln Navigator 3.5L EcoBoost High-Output Engine: Problems, Identification, and Used Replacement

Engine Identification: Confirming the Correct High-Output 3.5L EcoBoost

The 2018 Lincoln Navigator uses a specific early-build version of the second-generation High-Output (HO) 3.5L EcoBoost V6 engine. This twin-turbocharged, direct-injected V6 is known for its impressive power but has critical design details that a buyer must verify before purchasing a used replacement. Failure to confirm these details can result in buying an incompatible engine.

Before purchasing, check the following on your vehicle:

Common Failure Symptoms

An engine may be failing if you experience one or more of the following symptoms:

• Loud Rattle on Cold Start: A prominent rattling or tapping sound from the front of the engine for 2-5 seconds after starting the vehicle cold is a classic sign of worn cam phasers.
• Engine Stalling or No-Restart: In some cases, worn cam phasers can cause the engine to stall during an auto start-stop event and fail to restart, possibly triggering diagnostic trouble code P164C.
• Excessive Oil Consumption: A noticeable drop in oil level between changes can indicate internal engine problems or valve cover issues.
• Rough Idling and Misfires: Can be caused by several issues, including carbon buildup on intake valves, failing ignition components, or stretched timing chains.
• Visible Oil Leaks: Puddles of oil under the vehicle often point to a leaking oil pan seal, a common issue on these early-build models.

Diagnostic Flowchart

Known Issues, Recalls & Technical Service Bulletins (TSBs)

This engine generation has several well-documented issues. When inspecting a used engine or performing a replacement, these items should be addressed.

Cam Phaser Rattle (TSB 23-2143 / CSP 21N03)

This is the most common issue. The original Variable Camshaft Timing (VCT) phasers can wear out, causing a loud rattle on cold starts as they lack oil pressure. Ford released an updated TSB for 2017-2020 models. The official repair is to replace all four cam phasers with updated, redesigned units. Many owners report repair costs between $3,000 and $4,000.

High-Pressure Fuel Pump Weld Failure (NHTSA Recall 18V392000 / Ford Recall 18S17)

This severe recall affects certain 2018 models built between February 20, 2018, and May 6, 2018. Welds on the high-pressure fuel pump assembly can fracture, leading to a fuel or oil leak. A fuel leak in the presence of an ignition source increases the risk of a fire. The remedy is to replace the high-pressure fuel pump assembly.

Two-Piece Oil Pan Leaks (TSB 20-2051)

Early-build 2018 models are prone to oil leaks from the factory RTV sealant on the two-piece oil pan. The plastic lower pan can warp, preventing a good seal. The fix involves meticulously cleaning the surfaces and resealing the pan with Motorcraft TA-357 High-Performance Engine RTV Silicone. Many owners opt to upgrade to the more reliable one-piece aluminum oil pan used on later models.

Excessive Oil Consumption (TSB 20-2423)

Some 2018-2020 models experience excessive oil consumption. The official remedy involves reprogramming the Powertrain Control Module (PCM) and replacing both engine valve covers.

Brake Master Cylinder Leak (NHTSA Recall 22V-150)

Affecting 2017-2018 F-150, Expedition, and Navigator models, the brake master cylinder can leak fluid into the brake booster. The remedy is to replace the brake master cylinder to prevent fluid leaks and potential loss of braking power.

Premature Water Pump Failure

High-mileage units are known to experience water pump failures. It is highly recommended to perform a preventative replacement of the water pump during an engine swap.

What Fails at Every Mileage Band

Under 60,000 Miles

Even low-mileage engines are not immune to the infamous cam phaser rattle. Reports show this can occur as early as 30,000 to 50,000 miles. One owner of a 2018 High-Output 3.5L EcoBoost reported phaser issues at 48,000 miles, while another experienced complete engine failure at 36,060 miles after a failed repair attempt for a rattling noise. Bad fuel injectors have also been diagnosed in this range.

• ✓Do during install (required): Standard replacements. Always replace single-use items like the high-pressure fuel line (Ford Part #HL3Z-9J323-C), torque-to-yield bolts (crankshaft pulley bolt, cam phaser bolts), and all relevant gaskets. Perform a fluid and filter service using 6.0 quarts of premium OE-spec 5W-30 full synthetic motor oil, a new Motorcraft FL-500S oil filter, and Motorcraft Orange or Yellow pre-diluted engine coolant (WSS-M97B57-A1 or WSS-M97B51-A1).
• ✓Do during install (recommended): Inspect Cam Phasers. Even on a low-mileage unit, listen for the characteristic cold start rattle. Given the high failure rate, preventative replacement with the latest revised parts during an engine swap is strongly recommended.
• ✓Cheap insurance while the engine is out: Replace all 6 OE-spec spark plugs, ensuring they are gapped to 0.030 inches.

60,000 - 100,000 Miles

Cam phaser failure remains a very common issue in this range, with many owners reporting the cold start rattle between 60,000 and 85,000 miles. One owner of a 2018 model had the engine replaced at 100,000 miles due to this issue. Turbocharger failure is also a possibility; one owner experienced failure of both turbos and the exhaust manifolds at 80,000 miles. Water pump failures often begin appearing around 50,000 miles.

• ✓Do during install (required): Mandatory Cam Phaser Replacement. If service history is unknown, it is critical to replace all cam phasers, timing chains, and tensioners with the latest updated parts. Thoroughly inspect the turbos for shaft play and replace the oil feed and return lines to prevent oil starvation.
• ✓Do during install (recommended): Preventative Water Pump Replacement. While the engine is out, replacing the water pump is cheap insurance against a future failure.
• ✓Cheap insurance while the engine is out: Replace the spark plugs, as EcoBoost engines are notoriously hard on ignition components.

100,000 - 150,000 Miles+

Turbochargers are a significant concern in this mileage range. While many last 120,000 to 150,000 miles with good maintenance, failure is common. If not already addressed, cam phaser and timing chain issues will almost certainly have presented by this point. Coolant leaks from turbo lines are also a known issue to inspect.

• ✓Do during install (required): Assume Major Component Replacement. Plan to replace the timing chains, guides, tensioners, and cam phasers as a complete kit. Perform a full gasket and seal service, including the front and rear main seals, valve cover gaskets, and the two-piece oil pan seal.
• ✓Do during install (recommended): Strongly Consider Turbocharger Replacement. Given that turbos typically last 120,000-150,000 miles, replacing them during an engine swap is highly recommended to prevent near-future failure and redundant labor costs.
• ✓Cheap insurance while the engine is out: Replace the water pump and spark plugs.

Real Owner Experiences

The following table highlights real-world failures and repair costs reported by owners of the 2018 3.5L EcoBoost High-Output engine.

Estimated Replacement Costs

Engine replacement costs vary based on the source of the engine, labor rates, and the scope of the work. The labor for an engine replacement on a Navigator is significant, often estimated between 16 and 24 hours.

Repair or Replace?

Deciding whether to repair your current engine or replace it entirely depends on the severity of the failure and the stacked costs of repairs.

• Cam Phaser Rattle / Timing System Overhaul ($3,500 - $7,000): This repair is common and makes sense when the rest of the engine is healthy (good compression, no oil consumption or bottom-end noise). The cost is significant but less than a full engine replacement.
• Two-Piece Oil Pan Leak ($500 - $1,200): If the leak is the only issue, repair makes sense. The repair involves significant labor to remove the pan, meticulously clean surfaces, and apply new sealant.
• High-Pressure Fuel Pump Failure ($800 - $1,500): When the pump fails but has not caused catastrophic damage, repair is manageable compared to an engine replacement. Check for recall eligibility first.

When Replacement is Smarter: Replacement becomes the smarter option when multiple major issues are present, such as cam phaser rattle combined with significant oil consumption, low oil pressure, or any internal metallic debris (e.g., bearing material in oil). If the cost of stacked repairs approaches or exceeds the cost of a quality used or remanufactured engine ($4,000 - $8,000+), replacement is more economical.

Installation Essentials & Common Mistakes

Proper installation is critical to the long-term reliability of a replacement engine. Reusing certain parts or skipping steps can lead to immediate and catastrophic failure. This is an expert-level DIY job requiring specialized tools.

Required Special Tools

• Steck Ford 3.5L/3.7L EcoBoost Engine Out Lift Plate Hoist Tool (Part #50133)
• Camshaft holding/alignment timing tool kit (OTC 303-1655 / 303-1656)
• Torx Plus TP55 socket and Inverted Torx sockets (e.g., E7)
• Crankshaft pulley/harmonic balancer puller
• High-pressure fuel line disconnect tools
• Bi-directional diagnostic scan tool (Ford IDS/FDRS or FORScan)

Key Installation Gotchas

• Turbocharger Oil Lines: The oil feed lines for the turbochargers contain small mesh screens that can become clogged with debris from the old engine. These lines and their fittings MUST be replaced to prevent oil starvation and immediate failure of the turbos.
• High-Pressure Fuel Line: The metal fuel line connecting the high-pressure pump to the fuel rail is a one-time-use, torque-to-yield part. Reusing it will cause a dangerous high-pressure fuel leak.
• Oil Pan Resealing: If reinstalling a two-piece oil pan, the surfaces must be perfectly clean, and the RTV sealant must be allowed to cure for at least 24 hours before adding oil. Rushing this step will guarantee a leak.
• Cab-Off Installation: Many professional shops lift the vehicle's cab off the frame to access the engine due to tight clearances.
• Wiring Harness: You must reuse the vehicle's original engine wiring harness to ensure electrical compatibility with body and chassis modules.

Questions to Ask Your Installer

• Have you worked on this specific High-Output 3.5L EcoBoost (Gen 2) before?
• Will you be performing a 'cab-off' installation, and is that included in the quote?
• Does your quote include replacing the single-use high-pressure fuel line and the turbocharger oil feed lines with new OEM parts?
• Does the quoted price include the mandatory PATS parameter reset and Crankshaft Position (CKP) sensor relearn required for it to start?
• How will you handle programming the 30-digit fuel injector IQA codes from the replacement engine into my vehicle's PCM?

Freight, Delivery & Pre-Purchase Verification

When ordering a used 3.5L EcoBoost engine, it will not arrive via standard parcel delivery. Based on verified shipping data, this engine assembly weighs approximately 450 lbs and measures roughly 36" x 36" x 40" before crating. It ships as LTL (Less-Than-Truckload) freight on a pallet.

Ensure your delivery location can accommodate a freight truck. If you do not have a loading dock or forklift, you must request liftgate service to lower the pallet to the ground. Always inspect the engine thoroughly for transit damage before signing the delivery receipt.

Before finalizing your purchase, verify the donor engine matches your vehicle by confirming the 8th digit of the VIN is G or T, the build date is on or before February 25, 2018, the oil pan is a two-piece design, and it is configured for an automatic transmission.

Before the First Start: Priming and Fluids

You must prepare your used 3.5L EcoBoost engine before turning the key. Used engines sit dry on warehouse shelves. If you start the engine without pumping oil through it first, you will damage the internal parts.

Mandatory New Fluids

Never reuse old fluids. Fill the replacement engine with the exact Ford-approved liquids:

• Engine Oil: Use 5W-30 synthetic blend or full synthetic oil. It must meet Ford specification WSS-M2C961-A1 (or the older WSS-M2C946-B1). Always install a brand-new oil filter.
• Engine Coolant: Use Motorcraft Yellow antifreeze (specification WSS-M97B57-A1) or Motorcraft Orange (specification WSS-M97B44-D). Mix the coolant half-and-half with distilled water.

The Oil Priming Procedure

You must build oil pressure before the engine actually runs. To do this, use the factory Clear Flood Mode. This is a computer setting that stops fuel from spraying into the cylinders when the gas pedal is pushed all the way down. It lets the engine spin to pump oil without actually starting.

1. Fill the engine with the correct amount of fresh oil and coolant.
2. Get in the driver's seat and press the gas pedal completely to the floor. Hold it down firmly.
3. While holding the gas pedal down, press the engine start button to crank the engine. Let it crank for 10 to 15 seconds.
4. Stop cranking. Take your foot off the gas pedal. Wait 30 seconds to let the starter motor cool down.
5. Repeat this process two or three times. Watch the dashboard. Stop when the low oil pressure warning light turns off or the oil pressure gauge moves up to a normal reading.

Frequently Asked Questions