Nissan Armada 2025-2026 Service and Repair Manual: Inspection

INSPECTION AFTER DISASSEMBLY

Cylinder Head Bolts Outer Diameter

• Cylinder head bolts are tightened by plastic zone tightening method. Whenever the size difference between and exceeds the limit, replace them with new one.

  

  	: 50.5 mm (1.988 in)
  	: 11 mm (0.43 in)

  Limit [ - ]

  : 0.16 mm (0.0063 in)

• If reduction of outer diameter appears in a position other than , use it as point.

Cylinder Head Distortion

NOTE:

When performing this inspection, cylinder block distortion should be also checked. Refer to Inspection.

Using a scraper, wipe off oil, scale, gasket, sealant and carbon deposits from surface of cylinder head.

CAUTION:

Never allow gasket fragments to enter engine oil or engine coolant passages.

At each of several locations on bottom surface of cylinder head, measure the distortion in six directions , , , , , and ).

• If it exceeds the limit, replace cylinder head.

Valve Dimensions

• Check the dimensions of each valve. For the dimensions, Refer to CylinderHead.

• If dimensions are out of the standard, replace valve and check valve seat contact. Refer to “VALVE SEAT CONTACT”

Valve Guide Clearance

Valve Stem Diameter

• Measure the diameter of valve stem with micrometer (A).

  

  Standard

  : Refer to CylinderHead.

Valve Guide Inner Diameter

• Measure the inner diameter of valve guide with bore gauge.

  Standard

  : Refer to CylinderHead.

Valve Guide Clearance

• (Valve guide clearance) = (Valve guide inner diameter) – (Valve stem diameter)

  Standard

  : Refer to CylinderHead.

• If the calculated value exceeds the limit, replace valve and/or valve guide. When valve guide must be replaced, Refer to Removal & Installation.

Valve Seat Contact

• After confirming that the dimensions of valve guides and valves are within the specifications, perform this procedure.

• Apply prussian blue (or white lead) onto contacting surface of valve seat to check the condition of the valve contact on the surface.

• Check if the contact area band is continuous all around the circumference.

  

  	: OK
  	: NG

  • If not, grind to adjust valve fitting and check again. If the contacting surface still has “NG” conditions even after the recheck, replace valve seat. Refer to Exploded View.

Valve Spring Squareness

• Set a try square (A) along the side of valve spring and rotate spring. Measure the maximum clearance between the top of spring and try square.

  

  	: Contact
  C	: V-block

  Limit

  : Refer to CylinderHead.

• If it exceeds the limit, replace valve spring.

Valve Spring Dimensions and Valve Spring Pressure Load

• Check the valve spring pressure at specified spring height.

  

  Standard
  	:Refer to CylinderHead.

• If the installation load or load with valve open is out of the standard, replace valve spring.

INSPECTION AFTER INSTALLATION

Inspection for Leakage

The following are procedures for checking fluid leakage, lubricant leakage.

• Before starting engine, check oil/fluid levels including engine coolant and engine oil. If any are less than the required quantity, fill them to the specified level. Refer to Fluids and Lubricants.

• Follow the procedure below to check for fuel leakage.

  • Turn ignition switch to the “ON” position (with engine stopped). With fuel pressure applied to fuel piping, check for fuel leakage at connection points.

• Run engine to check for unusual noise and vibration.

  NOTE:

  If hydraulic pressure inside chain tensioner drops after removal/installation, slack in guide may generate a pounding noise during and just after the engine start. However, this does not indicate a malfunction. The noise will stop after hydraulic pressure rises.

• Warm up engine thoroughly to check that there is no leakage of fuel, or any oil/fluids including engine oil and engine coolant.

• Bleed air from lines and hoses of applicable lines, such as in cooling system.

• Summary of the inspection items:

  Items		Before starting engine	Engine running	After engine stopped
  Engine coolant		Level	Leakage	Level
  Engine oil		Level	Leakage	Level
  Transmission / transaxle fluid	AT & CVT Models	Leakage	Level / Leakage	Leakage
  	MT Models	Level / Leakage	Leakage	Level / Leakage
  Other oils and fluids*		Level	Leakage	Level
  Fuel		Leakage	Leakage	Leakage
  Exhaust gases		—	Leakage	—

  *: Power steering fluid, brake fluid, etc.

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