GM 5.3L LS4 Engine Specs, Problems, Reliability, Info

5.3 V8 LS4 Engine Overview

The LS4 is a 5.3-liter gasoline naturally aspirated, all-aluminum Gen IV small-block V8 engine used in GM full-size passenger cars between 2005-09. The LS4 is a unique motor because it is the only LS engine adapted for transverse front-wheel-drive applications. It is also the first member of the Small Block engine family to feature GM's Active Fuel Management technology (cylinder deactivation). The 5.3L LS4 engine was used in FWD vehicles such as the Pontiac Grand Prix GXP, Chevrolet Impala SS, Monte Carlo SS, and Buick LaCrosse Super. By the way, LS4 can also refer to a 7.4L (454 cu in) Chevy Big-Block engines from the 1970s, and they do not have anything in common. So, let's take a closer look at the 5.3L LS4, learn about its specs, features, reliability, and common problems.

LS4 Engine Features

This engine is based on the fourth-generation Small Block architecture and has the same displacement as the Vortec 5300 (LH6/LC9/LY5), but it uses an aluminum cylinder block with sleeves instead of iron block. The LS4 block also features a 90-degree cylinder angle, 4.40-inch (111.8 mm) bore spacing, and 6-bolt main caps. It came with a cast-iron crankshaft, forged powder metal connecting rods, and aluminum flat-top pistons. The crankshaft is 13mm shorter than the standard. That reduced the length of the engine and allowed it to fit into the FWD engine bays.

On top of the block, there are aluminum OHV cylinder heads with 2 valves per cylinder, cathedral intake ports, and D-shaped exhaust ports. These heads are based on the LS6 heads. Intake valve diameter is 2.000 inches (50.8 mm), exhaust valve diameter is 1.575 inches (40.0 mm). The LS4 is a classic pushrod V8. It came with a single hollow steel hydraulic-roller camshaft inside the block, 7.385-inch long pushrods, and die-cast roller rocker arms. The stock 2005-07 camshaft specs: 193/193 duration (intake/exhaust), 0.482 in./0.482 in. valve lift (intake/exhaust); 114 degree lobe separation. In 2007 the engine was upgraded with a new camshaft with a 1-bolt cam gear attachment instead of 3-bolt. This camshaft has the following specs: 196/201 duration (intake/exhaust), 0.481 in./0.481 in. valve lift (intake/exhaust); 116 degree lobe separation.

While the LS4 has Active Fuel Management (AFM), it still lacks a Variable Valve Timing (VVT) system. The AFM (also known as displacement on demand (DoD)) can turn off half of the cylinders under light-load conditions to improve fuel economy (usually while driving on a highway). This technology uses a solenoid to deactivate the lifters on selected cylinders.

The 5.3-liter LS4 engine is equipped with a sequential fuel injection (port injection) and advanced manifold absolute pressure (MAP) sensor. The intake manifold is made of plastic, and it utilizes a 4-bolt, 76 mm throttle body. The ignition system on 2005–2007 models features a coil-near-plug design and a 24x camshaft reluctor ring. Then, the LS4 was fitted with an advanced 58X reluctor ignition. All electronic systems and operations are managed by an E67 Engine Control Module (ECM). It is also worth noting that the LS4 is not Flex-Fuel capable, can run on regular gas but premium gas is recommended. The stock engine revs up to 6,000 RPM and produces 300-303 hp and 323 lb-ft (438 Nm) of torque.

Engine Specs

Known Problems

The 5.3 LS4 engine has earned a reputation for its good reliability and performance for its size. While the engine itself is based on a robust platform of LS and Vortec V8s, its transverse layout can lead to unique problems, especially after heavy use. In addition, nothing lasts forever, and LS4 engines eventually wear out and break down. Here are some of the most common LS4 engine problems:

• Lifter failure: This is a common problem related to the AFM (or DoD) system. A dropped lifter can be damaged by hitting the cam lobe. Then, metal shavings and dust can get into the oiling system and cause severe damage to the engine.
• Excessive oil consumption: A widespread problem, also often linked to the AFM/DoD system. The frequent deactivation and activation of cylinders by the AFM system over time can lead to accelerated wear and tear on the cylinder walls, pistons, and valvetrain components. Oil issues are more common with engines that are used primarily on highways.
• Intake manifold failure: The LS composite intake manifolds are prone to cracking, especially if they are exposed to excessive heat or if the bolts are over-tightened.
• Transmission issues: The front-wheel-drive 4T65E transmission is a weak link. It is not as strong as the engine. A torque converter and torque converter clutch failure are common problems with this transmission.

5.3L LS4 Reliability Summary

Drawing the line, GM 5.3L LS4 V8 engine, is it good? Yes, this engine is generally reliable, strong V8 motor with adequate power and fuel consumption. At the same time, it is a modern engine that requires good care, using high-quality oil and premium gas — key factors for long life. With proper maintenance, the LS4 engine can last for many years and well beyond 200,000 miles.