What is the History of GM's 3.6L High Feature V6 Engine?
GM's 3.6L engine debuted in the 2004 Cadillac CTS and it quickly became one of GM's most widely used V6 engines in cars, trucks, and SUVs. The original 3.6L was identified under the option code LY7 and featured a 10.2:1 compression ratio, dual overhead camshafts, and a variable valve timing system. Soon after the release of the LY7 3.6L, GM introduced an improved version of its 3.6L engine, the LLT. The new engine was equipped with a direct fuel injection system, a higher 11.3:1 compression ratio and better fuel economy. The LLT version debuted in the 2008 Cadillac STS and was used up to 2017 in the Chevrolet Traverse. Following the LY7 and LLT, several new versions have been released as GM continues to dial in and improve its most popular V6 engine.
What 3.6L Engines Have Timing Chain Issues?
The majority of the timing chain issues are with the LY7 and earlier versions of the LLT 3.6L engine. By the 2012 model year, GM had made several changes to help address the timing chain issues the 3.6L engine was having. Although vehicles after the 2012 model year may still have timing chain problems, it is much less common than years past.
Why Do the GM 3.6L Engines Have Timing Chain Problems?
There are several factors that can cause timing chain systems to fail. While some of it can be blamed on the engine design, the number one cause of timing chain failure or stretch is from inadequate lubrication. Lack of regular engine oil maintenance causes engine oil to break down and degrade. This results in the timing chain system not being lubricated properly. Over time this will cause excessive wear to the timing components, causing the timing chain to stretch in length and in some cases fail completely. GM compounded this issue on earlier models with the use of an oil life monitor that was calibrated to allow excessive mileage between oil changes.
What Happens When Timing Chains Fail on the GM 3.6L?
When a timing chain stretches, it affects the correlation between the camshafts and crankshaft. This results in the engines valves opening and closing at the wrong time. Since the correlation between the camshafts and crankshaft is closely monitored by the engine control module (ECM), a check engine light is usually the first indication of a timing chain issue. If the timing chain stretch worsens, it will cause the engine to run poorly and possibly cause the engine to misfire. In extreme cases the timing chain may break or stretch far enough to cause a no start condition.
What Codes Set When a 3.6L Timing Chain is Bad?
The timing chain system on the GM 3.6L uses 3 separate timing chains, a primary chain and two secondary chains. The primary chain affects the timing on both banks while each secondary chain only affects the timing on the cylinder head or bank it is on. The ECM will set different diagnostic trouble codes (DTCs) depending on which cylinder bank it detects has a correlation issue or is out of time, bank 1, bank 2 or both banks. Issues with bank 1 will set P0016, P0017 and/or P0008, Issues with bank 2 will set P0018, P0019 and/or P0009.
Do Codes P0008, P0009, P0016, P0017, P0018, P0019 Indicate a Timing Chain Is Bad On a 3.6L?
Diagnostic trouble codes (DTCs) alone do not indicate faulty components. Although these DTCs are commonly set due to stretched timing chains on the 3.6.L engine, other problems can cause these DTCs to set, such as faulty or stuck VVT components or issues with camshaft and crankshaft sensors.
How Do I Diagnose GM 3.6L DTC's P0008, P0009, P0016, P0017, P0018, P0019?
Diagnosing timing chain correlation DTCs can be difficult and complex. To aid in diagnosing DTCs and timing chain issues refer to:
How Do I Replace a GM 3.6L Timing Chain?
For an instructional video and helpful hints to replace the timing chains on your GM 3.6L engine, refer to: