A timing chain is the critical connection between your engine’s camshaft and crankshaft. Located in the front of the motor, the chain is run through a series of guides, gears, and pulleys. There is also usually a chain tensioner that has the critical job of keeping the chain tightened within a specific specification.
A properly tightened timing chain is critical to keeping your engine’s well, … timing in check.
Timing chains have made a recent resurgence over timing belts because the chains have a longer life expectancy. Well, most of them anyway.
Like any component in your car a timing chain will eventually need maintenance of replacement. But if you regularly maintain your oil, a lubricated timing chain shouldn’t give you much trouble for 120,000+ miles and can last for upwards of 300,000+ miles1.
Even with proper maintenance, the timing chains in many of GM’s 2007-2010 2.8L and 3.6L V6 engines are susceptible to stretching. Owners of vehicles with these engines, like the Buick Enclave, have experienced issue due a stretched timing chain as early as 40,000 miles.
What Happens When There’s Slack in the Timing Chain?
Intake, compression, combustion, and exhaust are the four stages of the internal combustion engine. In order to achieve those stages over and over again, pistons and cylinders have to move in unison with the precision of a classical ballet.
The timing chain is the conductor, controlling the timing of all those moving parts.
When the timing chain has slack it can throw the pistons and valves into more of an interpretive jazz dance. It sorta works at first … you know, in an artsy way. But eventually pistons start misfiring, valve timing is thrown off, a trumpet player goes off key, and before you know it your engine is destroyed.
Timing chain slack can be due to a defective chain tensioner, or the result of a worn out and stretched chain.
Symptoms of a stretched timing chain include:
- A check engine light should come on once sensors in the engine realize the timing is thrown off
- You’ll start to notice a rattle, especially at idle as the loose timing chain vibrates around the engine.
- The engine will start to misfire as combustion timing is thrown off.
- You might find metal shavings in the oil as small bits of the timing chain fall off or shavings accumulate as your camshaft gets scored by the chain. It could also cause dreaded oil sludge.
- Mechanics might tell you the timing chain “jumped a tooth” as it was improperly tensioned.
- In the worst case scenario, pistons smash into the valves, bending them resulting in catastrophic engine failure.
Engine Codes P0008 and P0017
Speaking of check engine lights, in TSB #PIP3423M Buick recommends technicians inspect for loose timing chain or tensioners when trouble codes P0016, P0017, P0018, P0019, P0008 or P0009 pop up.
The most common codes owners see when experiencing timing chain issues are P0008 and P0017.
Why Does GM’s 3.6L V6 Timing Chain Stretch?
The most common cause of timing chain stretch is irregular oil changes. If the timing chain isn’t properly lubricated, it will start to wear out and elongate as its pulled through guides and around gears.
That’s the hill GM was originally willing to die on as it blamed the problem on owners and irregular oil changes.
They lightened their stance slightly in 2011 with Customer Satisfaction Program 10287 which offered to reprogram the engine control module (ECM) in certain vehicles, like the 2009 Enclave.
General Motors was aware of the problem since 2007 and continued to manufacture with the problem in future models and offers no relief to consumers with this exorbitant cost to repair estimated at $3400. – 2010 Enclave owner
GM’s Extended Warranty for 2009 Enclave Owners
In November 2012, GM released a special coverage adjustment (#11340C) for timing chain wear in 2.8L and 3.6L V6 engines (LP1/LY7/LLT).
In their letter to customers, they admitted that the previous “fix” didn’t work and the problem could happen even with regular oil changes:
Recently, you took your vehicle to your dealer to have Customer Satisfaction Program 10287 performed. Your dealer reprogrammed the engine control module to prevent premature wear of the timing chain and the illumination of the Service Engine Soon light. Further analysis has shown that the reprogramming may not fully correct this condition for all vehicles; we, therefore, are providing you with additional protection for the timing chain.
To remedy the problem, GM extended warranty coverage on the timing chain to 10 years / 120,000 miles from the date the vehicle was originally placed in service.
If the vehicle’s “service engine soon” light came on and it turned out to be timing chain related, the chain would be replaced free of charge within the extended warranty period.
Compensation was also offered to owners who already paid for timing chain repairs.
Timing chains that look like they’re about to pop will get replaced within the extended warranty period, free of charge. If a timing chain replacement isn’t necessary, dealerships are instructed to reprogram the engine control module (ECM).
Where Does That Leave Other Owners?
Even though the engine design basically stayed the same, the coverage for Enclave owners was limited to the 2009 model year.
Without mentioning names, let’s just say that left 2008 and 2010 owners up a certain creek without a paddle.
Needless to say, we are not very happy about this especially as it appears to be an issue in the past and I suspect our enclave was made with 2009 materials and therefore should be covered under the same 2009 extended warranty … Essentially they have a faulty timing chain whose extended warranty didn’t cover enough years and ours stretched and ended up damaging the engine and the total repair was $9911
Estimated Timing Chain Repair Cost
The estimated repair cost for a stretched timing chain in a Buick Enclave is between $3200-$3400.
Why so expensive? While the chain itself isn’t all that much, the process of replacing involves some serious labor like taking out the entire engine and disconnecting the transmission. Additionally, a stretched timing chain will almost certainly damage other components that will also need replacement like cylinder heads, camshaft position sensors, O2 sensors, etc.