2008 INFINITI G37 Cylinder Head: Diagnosing Failure, VVEL Noise, and Replacement Costs

Symptoms of a Failing 2008 G37 Cylinder Head

A cylinder head problem can present in several ways, ranging from subtle performance issues to catastrophic engine failure. It's important to distinguish between a less severe external leak and a more serious internal failure like a blown head gasket or a cracked head.

• Overheating Engine: This is a classic sign. If the head gasket fails, hot combustion gases can leak into the cooling system, or coolant can leak out, causing the engine to run hot. If your temperature gauge suddenly spikes, pull over immediately to prevent severe engine damage.
• White Exhaust Smoke: Dense, sweet-smelling white smoke from the exhaust pipe that doesn't disappear after the engine warms up is a tell-tale sign that coolant is being burned in the combustion chambers. This is often caused by a breach in the head gasket or a crack in the cylinder head itself.
• Milky or 'Chocolate Milk' Engine Oil: Finding a creamy, light-brown substance on the oil dipstick or under the oil cap indicates that coolant has mixed with the engine oil. This is a serious condition that compromises the oil's ability to lubricate, leading to rapid engine wear.
• Unexplained Coolant Loss: If you constantly need to top off your coolant but can't find any visible leaks from hoses or the radiator, the coolant may be leaking internally into the cylinders or the oil passages. Bubbling in the coolant overflow tank when the engine is running is a strong indicator of a head gasket leak pushing exhaust gas into the cooling system.
• Engine Misfires and Rough Idle: A cylinder head issue can cause a loss of compression, leading to a rough idle, hesitation during acceleration, and engine misfire codes like P0300 (Random Misfire) or P030X (specific cylinder misfire).
• Ticking or Tapping Noises: While many things can cause a ticking noise, a specific tapping sound from the driver's side of the engine on a G37 can be related to the VVEL actuator housed in the cylinder head.

Is It the Cylinder Head or Something Else?

Before condemning the cylinder head, it's crucial to rule out other common VQ37VHR issues that can cause similar symptoms:

• Plastic Heater Hose Connector: These engines are known for a small plastic connector in the heater hose system, located near the firewall on the passenger side, that can become brittle and crack, causing a mysterious coolant leak. Check this area carefully for signs of dried coolant before assuming an internal leak.
• Water Pump Failure: The water pump can fail and leak coolant, often from a weep hole, which can be difficult to see. This will cause overheating and coolant loss.
• Torn Intake Boot: A random misfire (P0300) and rough running can be caused by something as simple as a cracked rubber intake boot located between the air filter box and the throttle body. This allows unmetered air into the engine, disrupting the air-fuel ratio.

Known Issues, TSBs, and Recalls

While the 2008 G37 has no engine-related recalls, there are well-documented common problems and Technical Service Bulletins (TSBs) you should be aware of.

VVEL Actuator Tapping Noise (TSB ITB11-034)

Some owners report a "tapping sound" from the driver's side (Bank 2) of the engine. Infiniti released a TSB acknowledging this issue, which relates to the VVEL actuator. The fix often involves a simple software update for the Powertrain Control Module (PCM) performed by a dealer, rather than a mechanical repair. If you hear a tapping noise, this should be investigated before considering head replacement.

Oil Gallery Gasket Failure

One of the most notorious issues with early VQ37VHR engines (2008-early 2012) is the failure of the paper oil gallery gaskets located behind the timing cover. When these gaskets fail, they cause a significant drop in oil pressure, which can trigger a P0011 or P0021 trouble code and put the car in limp mode. While this is not a cylinder head failure, replacing these gaskets is an intensive job that requires removing the timing cover. Since cylinder head replacement also requires removing the timing cover, it is absolutely essential to replace the gallery gaskets with the updated metal versions during the job.

Recalls

The only significant safety recall for the 2008 INFINITI G37 concerns the passenger-side Occupant Classification System (OCS), which could prevent the airbag from deploying correctly. This recall is unrelated to the engine or cylinder head.

Buying a Used 2008 G37 Cylinder Head: What to Check

A used OEM cylinder head is often a cost-effective and reliable choice, as factory castings are typically of high quality. However, careful inspection is critical to avoid buying a bad part.

• Verify Compatibility: The cylinder heads are side-specific. The right (passenger side) head is different from the left (driver side) head. Ensure you are buying the correct one for your needs. The initial part numbers provided (11040- series for right, 11090- series for left) are a good starting point. Also, confirm the casting number is 'EYO' if possible, as this was specified for this engine family.
• Check for Warping: Overheating is the number one killer of cylinder heads. Use a precision straightedge and feeler gauges to check the mating surface for flatness. Lay the straightedge across the surface in several directions (lengthwise, widthwise, and diagonally). Any gap larger than the manufacturer's specification (typically a few thousandths of an inch) means the head is warped and must be resurfaced by a machine shop.
• Inspect for Cracks: Carefully examine the entire head for cracks, paying close attention to the areas between valve seats and around spark plug holes. Cracks can be very fine and difficult to see. A machine shop can pressure test the head to guarantee it has no hidden cracks.
• Examine the VVEL Assembly: The VVEL system is complex and sensitive. Inspect the assembly for any signs of damage, scoring, or binding. A complete, intact used head is highly preferable to one that has been stripped of its components.
• Look at the Camshafts: Check the camshaft lobes and bearing journals for scoring, discoloration from heat, or excessive wear. These are signs of oil starvation, which could indicate the donor engine had other problems (like failed gallery gaskets).

Replacement Cost & Difficulty

Replacing the cylinder head on a 2008 Infiniti G37 is a highly complex and labor-intensive job, primarily due to the Dual Overhead Cam (DOHC) design and the intricate VVEL and timing chain systems.

• Installation Difficulty: 5 out of 5. This is not a DIY job for the average home mechanic. It requires specialized tools for holding the timing chains and VVEL components, in-depth knowledge of the VQ37VHR engine, and extreme precision. Professional installation is strongly recommended.
• Estimated Labor Time: A professional technician will typically quote 15-20+ hours for this job.

Frequently Asked Questions (FAQ)