2017-2020 Pathfinder & QX60 3.5L VQ35DD: Problems, Identification, and Used Replacement

Engine Identification: Is This Your Engine?

The 2017–2020 Nissan Pathfinder and Infiniti QX60 use a 3.5-liter V6 engine known as the VQ35DD. This engine is part of Nissan's long-running VQ series but has a key feature that makes it different from older versions: direct injection. In a direct injection system, fuel is sprayed directly into the engine's cylinders at high pressure. This is different from the older VQ35DE engine, which used multi-port fuel injection (fuel is mixed with air before entering the cylinder). Because of this major difference, the VQ35DD is not interchangeable with the older VQ35DE.

How to Confirm Your Vehicle's Engine

You can quickly check if your vehicle has the VQ35DD engine by looking at your Vehicle Identification Number (VIN).

• VIN Check: The 4th digit of your VIN must be 'D'. This confirms your vehicle was built with the VQ35DD engine.
• Engine Code Location: The engine code "VQ35" is stamped on the engine block itself. You can find it on the front, right-hand side of the cylinder block, near where the engine connects to the transmission bellhousing.

Common Failure Symptoms

When the VQ35DD engine has a serious problem, it will show several warning signs. Knowing these symptoms can help you decide if a replacement is necessary.

• Metallic Rattle on Cold Start: A brief rattling or chain-slapping noise when you first start the engine, which then goes away, is a classic sign of worn timing chain guides and tensioners. 🎬 Listen to an example of this cold start rattle If ignored, this can lead to catastrophic engine failure.
• Engine Sludge or Milky Oil: Finding a thick, dark sludge when you check the oil, or a milky, coffee-colored substance under the oil cap, points to a failed Positive Crankcase Ventilation (PCV) system and severe oil breakdown. This can block oil passages and starve the engine of lubrication.
• Rough Idle and Power Loss: As these engines age, carbon can build up on the intake valves, a common issue with direct-injection engines. This buildup can cause the engine to run rough, misfire, and feel less powerful.
• Engine Overheating: If the engine overheats but you can't find any external coolant leaks, it may be due to a failing internal water pump or a failed radiator cooling fan (a known issue between 20,000 and 80,000 miles).
• Oil Consumption: Piston ring wear can lead to increased oil consumption. If not monitored, this causes oil starvation and catastrophic failure.

Diagnostic Flowchart

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

This engine has several well-documented issues. Understanding them is key to a successful repair.

Engine Sludge & PCV System Failure

The VQ35DD engine runs hot and is known for degrading oil quickly. The PCV system, which is supposed to remove harmful gases from the engine, can become overwhelmed or fail. This traps blowby gases and moisture in the oil, causing it to break down and form sludge. This sludge can block oil passages, leading to catastrophic engine damage. The best prevention is performing oil changes every 3,500 to 5,000 miles with a high-quality full synthetic oil and regularly replacing the PCV valve (Part # 11823-6KA0A).

Timing Chain & Guide Wear

The timing chain system uses plastic guides that can wear out over time. When they wear, the timing chain becomes loose and can rattle against other parts, especially on a cold start before oil pressure builds up. If you hear this noise, the timing chain, guides, and hydraulic tensioners must be replaced immediately to prevent the chain from skipping a tooth or breaking, which would destroy the engine.

Intake Valve Carbon Buildup

Because fuel is injected directly into the cylinders, it no longer washes over the intake valves to keep them clean. Over time, oil vapor and combustion byproducts bake onto the valves, causing a hard carbon buildup. This restricts airflow, leading to a rough idle, misfires, and reduced power. The only effective remedy is a manual cleaning process, such as walnut blasting, which should be done by a professional shop.

Technical Service Bulletin NTB18-026

For 2017–2018 models, Nissan issued a TSB for an air-fuel ratio imbalance that could cause drivability issues. The fix involves reprogramming the Engine Control Module (ECM) and performing an Idle Air Volume Learn procedure. This TSB corresponds to NHTSA ID 10133185.

ABS Actuator Pump Recall

What Fails at Every Mileage Band

Under 60,000 Miles

Even at lower mileages, these engines can show signs of sludge (often starting around 50,000 to 60,000 miles) if the previous owner followed the factory-recommended long oil change intervals instead of shorter 3,500-5,000 mile intervals. A faulty or collapsed PCV hose can cause excessive crankcase pressure, leading to oil leaks and sludge formation. Radiator cooling fan failures are also reported between 20,000 and 80,000 miles, which can cause overheating.

• ✓Do during install (required): Replace PCV valve and hose with new OEM parts (Part # 11823-6KA0A) to prevent sludge.
• ✓Do during install (required): Use 5.1 quarts of high-quality full synthetic 0W-20 or 5W-30 oil and a new OEM filter.
• ✓Do during install (required): Replace all essential gaskets and seals (intake, exhaust, valve covers, rear main seal).
• ✓Cheap insurance while the engine is out: Consider replacing the thermostat and internal water pump.

60,000 - 100,000 Miles

In this range, a metallic rattle on cold starts becomes a common sign of wearing timing chain guides and tensioners, sometimes appearing as early as 80,000 miles. Carbon deposits on intake valves can begin to cause rough idling or reduced power. If not addressed with frequent oil changes, sludge buildup can lead to catastrophic engine failure.

• ✓Do during install (required): ALL items from the 'Under 60K' band.
• ✓Do during install (required): Replace spark plugs, all filters, and the serpentine belt.
• ✓Do during install (recommended): Perform a manual intake valve cleaning (e.g., walnut blasting) to remove carbon deposits.
• ✓Cheap insurance while the engine is out: Strongly consider replacing the full timing chain set (chains, guides, tensioners) as a preventative measure, especially if any startup rattle was noted on the donor engine.

100,000 - 150,000+ Miles

Past 100,000 miles, what begins as a timing chain rattle can progress to jumped timing or complete chain failure, causing severe engine damage. The labor-intensive internal water pump is a known failure point on high-mileage units. Piston ring wear can also lead to increased oil consumption.

• ✓Do during install (required): ALL items from the previous bands.
• ✓Do during install (required): Timing chain service (chains, guides, tensioners) is mandatory, not optional, at this mileage.
• ✓Do during install (required): Internal water pump and thermostat replacement is mandatory.
• ✓Do during install (required): Replace all seals, including front and rear main seals, and valve cover gaskets.
• ✓Do during install (recommended): Thoroughly clean the oil pan and inspect the oil pickup tube for sludge or debris.

Real Owner Experiences

Repair or Replace?

Deciding whether to repair your current VQ35DD or replace it with a used unit comes down to the severity of the damage and the cost of labor.

• Intake Valve Carbon Buildup: This is a maintenance-style repair for direct-injection engines. If the engine is otherwise healthy, a manual cleaning typically costs $500 to $1,300. Repair makes sense here.
• Minor to Moderate Engine Sludge: If the sludge has not yet caused oil starvation or damaged timing components, chemical engine flushes ($150-$400) or cleaning the oil pickup screen ($300-$600) can save the engine.
• Timing Chain & Guide Wear: If caught early (just a startup rattle), replacing the chain, guides, and tensioners costs $1,500 to $4,000 due to extensive labor and expensive OEM parts. Repair makes sense if the rest of the engine is in excellent condition.

When Replacement is Smarter: If the engine has suffered catastrophic failure from a skipped timing chain, severe oil starvation due to sludge (indicated by knocking sounds), or a cracked block, replacement is necessary. If a full rebuild for severe sludge approaches $8,500+, replacing it with a lower-mileage used engine is the more economical choice.

Replacement Cost Estimates

The cost to replace a VQ35DD engine can vary widely based on the type of replacement unit and local labor rates. The labor for this job is significant, typically estimated between 14 and 24 hours.

Installation Essentials: What to Know Before You Start

Replacing this engine is a complex job best left to experienced technicians. Here are critical points to be aware of.

What is Included (and Excluded) with a Used Engine

When buying a used VQ35DD from a professional auto recycler, it typically includes the engine block, cylinder heads, internally lubricated parts, oil pan, valve covers, intake manifold, timing covers, fuel injection system, throttle body, and harmonic balancer. It will generally not include the A/C compressor, starter, power steering pump, alternator, exhaust manifolds, external engine wiring harness, or engine mounting brackets. You will need to transfer these from your old engine.

Required Tools

This is an expert-level job requiring specialized tools, including:

• Engine hoist/crane or subframe lift table
• Flywheel/Flexplate Holder Tool
• Fuel pressure release tool
• High-pressure fuel line disconnect tools
• OEM-compatible scan tool (Nissan CONSULT-III plus or equivalent)

Required Parts & Consumables

When installing a used engine, always replace the following items to ensure reliability and prevent future problems:

• Engine Oil (5.1 quarts of full synthetic 0W-20 or 5W-30)
• OEM-spec Oil Filter
• Nissan Long Life Blue Coolant (50/50 pre-diluted mix)
• New OEM PCV Valve & PCV Hose (Part # 11823-6KA0A)
• Six new OEM-spec iridium spark plugs
• Intake manifold gaskets (upper and lower plenum)
• Exhaust manifold gaskets
• Thermostat and Gasket
• Valve cover gaskets (with integrated spark plug tube seals)
• Rear main seal
• Serpentine/Drive Belt
• Torque-to-Yield (TTY) crankshaft pulley bolt and flexplate-to-crankshaft bolts

Installation Gotchas & Common Mistakes

• FWD vs. AWD Oil Pan: The upper oil pan is different between Front-Wheel Drive and All-Wheel Drive models. You must transfer your original upper oil pan if the donor engine's drivetrain does not match your vehicle.
• AWD Transfer Case (PTU) Alignment: Misalignment can bind the intermediate shaft, damage splines, or cause severe vibrations. Replace PTU seals during reinstallation.
• High-Pressure Fuel System: This is a direct-injection engine. The fuel system must be properly depressurized before service. High-pressure fuel lines and injector O-rings are single-use items and must be replaced.
• Torque-to-Yield (TTY) Bolts: Crankshaft pulley and flexplate-to-crankshaft bolts must be replaced with brand-new OEM fasteners.
• Fragile eVTC Connectors: Electronic Variable Timing Control solenoids on front timing covers have fragile plastic connectors easily cracked during install.
• Integrated Spark Plug Tube Seals: Seals are integrated into the valve cover; if leaking, the entire valve cover must be replaced.
• Reusing Old Parts: Never reuse the old PCV valve, spark plugs, or gaskets. Reusing the old PCV valve is a primary cause of the sludge issue that destroys these engines.
• Wiring Harness: The engine wiring harness must match the vehicle's drivetrain (FWD vs. AWD) and model year. It is highly recommended to transfer your original wiring harness, sensors, and brackets from your old engine.
• Debris: Failing to clear the intake manifold of debris from a previous catastrophic engine failure will destroy the new engine.

Required Programming and Calibration

After the engine is installed, it will not start and run correctly without several electronic procedures. A dealer-level scan tool like Nissan's CONSULT-III plus is required.

• Immobilizer Re-marriage (NATS): The engine computer (ECU) must be synchronized with the vehicle's security components.
• Relearn Procedures: Several systems must be recalibrated, including the Idle Air Volume Learn (IAVL), Throttle Valve Closed Position Learning, Accelerator Pedal Released Position Learning, and Crankshaft Position (CKP) Sensor Phase Relearn. Failure to perform these steps will result in a poor-running engine.

Freight & Delivery Reality

A complete VQ35DD engine assembly is a massive piece of machinery. Verified shipping data shows this unit weighs approximately 490 lbs and measures roughly 35" x 35" x 36" before crating. Because of this size and weight, it ships as Less-Than-Truckload (LTL) freight on a pallet, not as a standard parcel.

When ordering a used engine, expect it to arrive via a large freight truck. You will need a loading dock, a forklift, or a truck equipped with a liftgate to safely unload it. Always perform a pre-purchase verification interview with the seller to confirm the VIN 4th digit is 'D' and to verify the drivetrain configuration (FWD vs. AWD). Upon delivery, thoroughly inspect the engine for any shipping damage before signing the driver's delivery receipt.

Arrival Inspection: Compression and Leak-Down Testing

When your used VQ35DD engine arrives, test its internal health before installing it. Do this while the engine is still on the shipping pallet.

Compression Test: A compression test measures how well each cylinder squeezes air. For the VQ35DD, a healthy used engine should produce between 150 and 200 PSI (pounds per square inch) in every cylinder. The most important rule is consistency. The pressure difference between the highest and lowest cylinders must not be more than 14 PSI. If one cylinder reads much lower than the others, the engine has internal damage.

Leak-Down Test: A leak-down test pumps compressed air into a cylinder to see how much air escapes. This tells you if the piston rings (metal bands around the pistons) or valves (metal doors that let air in and out) are sealing properly. A good used VQ35DD engine should show less than 15 percent air leakage in each cylinder. If you hear air hissing from the exhaust, intake, or oil cap area during this test, the engine has a bad seal.

Frequently Asked Questions (FAQ)