4 Common Chevy LS6 Engine Problems

GM’s LS6 engine is built off of the LS1 – which was known to have a few weak points and problems. It did however get a number of upgrades to the heads, intake manifold, block, and a number of other smaller components. So the question is, is the LS6 more reliable?

Fortunately, all of these updates turned the LS6 into a very reliable engine. The engine does still suffer from a couple problems including broken valve springs, rocker arm failure, excessive oil consumption, and overheating. While this doesn’t pain a great picture, the engine offers great reliability and fixed a lot of the serious problems that the previous generation had. In this article we’re going to dig into each of these problems in-depth.

LS6 Engine Problems

• Excess Oil Consumption
• Broken Valve Springs
• Engine Overheating
• Rocker Arm Bearing Failure

Overall, the LS6 is quite reliable as a daily driver when left in stock condition. The majority of the LS6 problems come from the 2001 model year understandably as this was a new engine. Most of the problems with the 2001 models were addressed in the 2002 engine refresh.

For a stock engine, there aren’t too many problems, or at least many catastrophic problems. Once you begin to modify the LS6, such as adding an upgraded intake, and use the car for track racing, drag racing, etc. then problems usually begin to appear. However, these problems can usually be mitigated with various additional upgrades such as cooling system improvements with things like a larger radiator and oil cooler.

1) Excess Oil Consumption Problems

LS6 engines are prone to excessive oil consumption, consuming as much as 1 quart of oil for every 500 miles. Excess oil consumption is most common in manual transmission cars and ones that frequently drive aggressively or at high RPMs. The oil consumption is caused by a design flaw in the PCV system and valley cover which causes oil to seep into the PCV system.

The LS6 has a unique valley cover that has oil separation baffles and PCV plumbing built into it. When the PCV baffles aren’t correctly sealed to the valley cover oil seeps past and enters the PCV system. When this happens you will likely notice some oil leaks underneath your car as well as some minor performance issues.

If you are experiencing excessive oil consumption it is imperative to make sure your engine is always topped off with oil. Keep an extra few quarts of oil in your trunk and top off as needed to prevent running on low oil which can cause catastrophic damage to your internals.

2) Broken Valve Springs

2001 LS6’s are known to break valve springs. When the valve spring breaks, it no longer has enough tension or pressure to properly operate the valve. It can cause the valve to not fully close or even cause the valve to fall into the cylinder where it might crash into the piston. Additionally, it results in the loss of compression within the cylinder with the broken spring.

Ultimately, broken valve springs cause serious power losses and performance issues, and can cause serious engine damage. If the valve collides with the piston it can destroy both of those components and the cylinder head.

Failure Symptoms

• Loud valve noise from the engine
• Loss of cylinder compression
• Very rough idling
• Misfires
• Lack of power and acceleration
• Check engine light (usually for misfires)

3) Overheating Issues

The LS6 is a great engine when left in stock form and street driven. However, once you add additional power to the mix and drive it hard, whether it be on the street or on a track, the stock cooling system becomes problematic. Overheating is most common on Z06’s that are tracked or raced and on street cars that are heavily modified.

Power creates heat. Racing creates prolonged periods of high engine temperatures. The radiator and the oil cooler on the LS6 aren’t built well for either of these conditions which can cause overheating if they are not upgraded. Adding either a larger oil cooler or radiator, or both, are common cooling system modifications to prevent overheating. While neither of these upgrades will necessarily create more horsepower they will improve reliability and help keep engine temps down which does have a performance impact.

Preventing engine heat is one of the best reliability mods you can perform.

4) Rocker Arm Bearing Failure

Early model LS6’s were also prone to rocker arm failure. Rocker arms are part of the overhead valve system and is responsible for pushing the valves open. The rocker arms take the circular movement from the camshaft and transform it into linear movement. The cam pushes the tappet and pushrod upwards causing the rocker arm to compress against the valve spring and open the valve. On the LS6 engine, the rocker arm bearings are what cause the rocker arms to stop functioning properly.

If the rocker arm breaks or the bearing fails it can affect the valves ability to properly open and close. When the arm break the valves can’t open, or fully open, which virtually takes out the whole cylinder by preventing air from entering or leaving the cylinder. Broken or worn valve springs can also cause rocker arm failure.

Symptoms

• Rough idling
• Cylinder misfires
• Tapping or clicking noise from the engine
• Low power and lack of acceleration
• Check engine light (misfires)

LS6 Reliability

Overall, the LS6 is an extremely reliable engine. Outside of some of the 2001 model years, the engine has very few problems and none that are serious in nature.

The block, pistons, valves, heads, etc. are all very strong and can handle some significant power before needing to be upgraded. The cooling system on the LS6 is a weak point and will need to be upgraded for track and high horsepower applications. Outside of this, the LS6 is capable of surpassing the 200,000 mile mark when stock and properly maintained.