GM 4.3 Liter V6 Vortec LU3 Engine

The LU3 features excellent torque, fuel efficiency, durability, low cost of ownership, and steady improvement — all of which contribute to its popularity as a base engine in GM’s light-duty full-size vans. A counter-rotating balance shaft helps balance primary crank vibration, while the latest in electronic controls and the inherent low-end torque delivery of this overhead-valve engine have combined to make the engine very popular.

Engine highlights:

• Cylinder Block and Rotating Assembly: the LU3 features an iron cylinder block based on the small-block V8 architecture. Inside the block, the rotating assembly consists of a strong iron crankshaft, lightweight aluminum pistons and cracked powder-metal connecting rods.
• Electronic Direct Ignition System: a trio of ignition coils is mounted above the former location of the conventional distributor (a unique “stub” shaft is used to drive the oil pump). Each coil is directed by the engine’s controller to fire two cylinders. The ignition system uses a 58X crankshaft-sensing reluctor wheel, similar to those used in GM’s Gen IV V8 engines.
• Additional details: The LU3 incorporates a number of features designed to optimize performance and durability, while helping keep down ownership costs. They include:
  • Machined water pump and specific gasket delivers better pump-to-block sealing
  • Cast rocker arms offer more precise tolerances
  • Low-permeable intake sealing system helps ensure minimal fuel emissions seeping out of the intake system
  • Three layers of insulated tubing for the exhaust manifolds helps reduce noise
  • Extended-life spark plugs are designed to go 100,000 miles (160,000 km) without the need for replacement
  • Extended-life Dex-Cool coolant maintains its cooling and corrosion-inhibiting properties for 150,000 miles (240,000 km)