Chevrolet Equinox Service Manual: Engine Component Description (LFX)

The High Feature V6 (VIN Code Identifier “3” for both cars and trucks) RPO LFX isa 3.6-Liter VVT-(Variable Valve Timing) engine with direct injection. The LFX hasE85-compatible valves and seats with special materials and coatings that require slightlydifferent service procedures from gasoline valves. The direct injection system placesthe high pressure injectors in the cylinder heads. This engine incorporates 2-intakeand 2-exhaust valves per cylinder, and uses a dual overhead cam design with individualintake and exhaust camshafts. A camshaft position actuator is mounted on each camshaft.The cylinders are arranged in 2-banks of 3 with a 60-degree included angle. The rightbank of cylinders are number 1-3-5 and the left bank of cylinders are 2-4-6, viewedfrom the flywheel end of the engine. The engine firing order is 1-2-3-4-5-6.

The cylinder block is constructed of aluminum alloy by precision sand-casting withcast in place iron cylinder liners. Each main bearing cap incorporates 6-bolts boltingthe cap into the engine block. Along with 2-outer and 2-inner bolts, 2-side boltsare used in the deep skirt block. To prevent aeration, oil return from the valvetrainand cylinder heads is channeled away from the rotating and reciprocatingcomponents through oil drain back passages incorporated into the cylinder heads andengine block. Pressure-actuated piston oil cooling jets are mounted between opposingcylinders. A knock sensor is located on the each side of the exterior of the engineblock. The crankshaft position sensor is located on the right side of the exteriorof the engine block.

The crankshaft is a hardened, forged steel design with 4 main bearings. Crankshaftthrust is controlled by the upper portion of number 3-main bearing. The crankshaftposition reluctor wheel is pressed onto the rear of the crankshaft in front of therear main journal. A micro encapsulated adhesive is used on the reluctor wheel toaid retention. The crankshaft is internally balanced, and has an integral oil pumpdrive machined intothe nose in front of the front main journal.

The connecting rods are steel and have full floating piston pins. The piston pinsare a slip fit in the bronze bushed connecting rod. Round wire retainers are usedto retain the piston pin into the piston. The cast aluminum pistons incorporate apolymer-coated skirt to reduce friction. The piston uses two low tension compressionrings and one multi-piece oil control ring. The top of the piston contains a shapedportion for the directinjection system to aid in fuel-air charge mixture and even combustion.

The camshaft drive system consists of one primary timing drive chain driven by thecrankshaft sprocket. The primary timing drive chain drives two intermediate driveshaft sprockets. Each oil-pressure-fed intermediate drive shaft sprocket drives separatesecondary timing drive chains. Each secondary timing drive chain drives the respectivecylinder head's intake and exhaust camshaft position actuators.

The primary timing drive chain uses two stationary timing drive chain guides and ahydraulically-actuated tensioner with built-in shoe. The tensioner minimizes timingdrive chain noise and provides accurate valve action by keeping slack out of the timingdrive chains and continuously adjusting for timing drive chain wear. The tensionerincorporates a plunger that adjusts out with wear allowing only a minimal amount ofbacklash. The tensioneris equipped with an oiling jet to spray oil onto the timing components during engineoperation. The secondary timing drive chains use a stationary timing drive chain guideand movable timing drive chain shoe. The secondary timing drive chain shoe is undertension from a hydraulically-actuated tensioner. All tensioners are sealed to thehead or block using a rubber coated steel gasket. The gasket traps an adequate oilreserve to ensure quietstart-up.

The engine incorporates a camshaft position actuator for each intake and exhaust camshaft.Camshaft phasing changes valve timing as engine operating conditions vary. Dual camshaftphasing allows the further optimization of performance, fuel economy and emissionswithout compromising overall engine response and driveability. Variable valve timingalso contributes to a reduction in exhaust emissions. It optimizes exhaust and inletvalveoverlap and eliminates the need for an exhaust gas recirculation-(EGR) system.

The camshaft position actuator is a hydraulic vane-type actuator that changes thecamshaft lobe timing relative to the camshaft drive sprocket. Engine oil is directedby a camshaft position actuator oil control valve to the appropriate passages in thecamshaft position actuator. Oil acting on the vane in the camshaft position actuatorrotates the camshaft relative to the sprocket. At idle, both camshafts are at thedefault or "home" position.At this position, the exhaust camshaft is fully advanced and the intake is fully retardedto minimize valve overlap for smooth idle. An internal lock pin locks the inner rotorto the outer camshaft position actuator housing at idle and maintains this positionduring start-up conditions. Under other engine operating conditions, the camshaftposition actuator is controlled by the engine control module-(ECM) to deliver optimalintake andexhaust valve timing for performance, driveability and fuel economy. The camshaftposition actuator incorporates an integral trigger wheel, which is sensed by the camshaftposition sensor mounted in the front cover, to accurately determine the position ofeach camshaft. The exhaust camshaft position actuator has a different internal configurationthan the intake camshaft position actuator since the exhaust camshaft position actuatorphasesin the opposite direction relative to the inlet camshaft position actuator.

The camshaft position actuator oil control valve-(OCV) directs oil from the oil feedin the head to the appropriate camshaft position actuator oil passages. There is oneOCV for each camshaft position actuator. The OCV is sealed and mounted to the frontcover. The ported end of the OCV is inserted into the cylinder head with a slidingfit. A filter screen protects each OCV oil port from any contamination in the oilsupply.

The camshaft front journal has several drilled oil holes to allow camshaft positionactuator control oil to transfer from the cylinder head to the camshaft position actuator.The center camshaft bolt hole is counterbored to allow oil to flow around the camshaftbolt and to the camshaft position actuator. Oil in this oil passage is used to movethe camshaft position actuator to the default or home position.

Radially outward from the center of the journal is a set of 4-drilled camshaft positionactuator oil holes. Oil in this group of oil holes is used to move the camshaft fromthe default position to a specific set position as determined by the ECM. Seal ringsare used at the front and rear of the front camshaft journal to prevent oil leakagefrom the camshaft position actuator hydraulic system. The seal is made from a plasticcompoundthat resists wear and has a diagonal end gap to enhance sealing. The camshaft positionactuator is mounted to the front end of the camshaft and the timing notch in the noseof the camshaft aligns with the dowel pin in the camshaft position actuator to ensureproper cam timing and camshaft position actuator oil hole alignment.

The cylinder heads are cast aluminum with powdered metal valve seat inserts and valveguides. The cylinder heads also feature integrated exhaust manifolds; the exhaustmanifolds are incorporated into the head casting. Two intake valves and two exhaustvalves are actuated by roller finger followers pivoting on a stationary hydrauliclash adjuster-(SHLA). In the E85 fuel compatible LFX engine, the valves and seatsare constructedwith specialized materials and coatings to perform properly in the E85 fuel environment.The intake valves in the LFX engine are slightly larger than those in the LFW engineto allow the additional air necessary for a 3.6L displacement engine.

Separate exhaust and intake camshafts are supported by bearings machined into thecylinder head. The front camshaft bearing cap is used as a thrust control surfacefor each camshaft. Each spark plug is shielded by a tube that is pressed into thecylinder head. Each spark plug ignition coil is also mounted through the spark plugtube. The engine coolant temperature-(ECT) sensor is threaded into the cylinder head.With direct injection,the high pressure injectors are located in machined bores below the intake ports.A stainless steel, high pressure fuel rail is attached to the intake side of the head.

The intake manifold assembly is used to deliver a dry-air charge to the combustionchamber. Fuel is introduced directly to the cylinder during the intake stroke. Asthe piston approaches top-dead center, the air-fuel mixture is ignited by the sparkplug. An electronically controlled throttle-(ETC), through the ECM, coordinates theinput from the driver with various control components.

Right hand-(RH) and left hand-(LH) designation through the engine mechanical sectionare viewed from the rear, non-front-cover side, of the engine or from inside the vehicle.These banks are also referred to as Bank-1-(RH) and Bank-2-(LH).