The GM 3.6L engine is a widely used V6 engine in many American-made SUVs, trucks, and cars. In fact, since its debut in 2004 in Cadillac CTS, this is the most popular 3.6L engine from General Motors to date.
The company started with the LY7 and then upgraded to LLT. Unlike the LY7, which had a 10.2:1 compression ratio, the LLT boasted a higher 11.3:1 ratio which meant better fuel economy.
General Look at the 3.6L GM Engine
The GM 3.6L is a powerful engine that has undergone several upgrades over the years. These upgrades have been undertaken to improve the engine's performance and correct some existing faults in the previous models.
Like many car engines, the GM 3.6L V6 engine has been dogged by some issues. The timing chain problems have been persistent and have been a headache for many car owners. If so many online car forums where car owners share ideas and ultimately get help through them, then the GM 3.6L engine timing chain problem is not something that one can wish away just yet.
The GM 3.6L engine boasts many benefits and, in some instances, is considered a V8 comparable in terms of power and performance. Indeed, many cars such as the Hummer 2, Chevrolet Camaro, and GMC Acadia use the GM engine.
The GM 3.6L engine comes with its share of issues, but in this article, we will take an in-depth look into the timing belt/chain problems that have dogged this engine for a long time.
Understanding the timing chain
The timing chain plays a vital role in internal combustion, ensuring the engine's proper running. The chain harmonizes the crankshaft and the camshaft rotation, and then the pistons and the valves will operate at optimal capacity.
But the camshaft and the crankshaft must be synced perfectly for this to be achieved. The timing chain has to run smoothly and without skipping any teeth. A properly working timing chain ensures the right amount of fuel, air, and exhaust gas are mixed before the piston is pushed down.
Though the chain is made of metal, it wears out. We will explore the problems associated with the GM 3.6L timing chain, which tends to wear out way too soon than those installed in many other cars.
The timing chain problems
While the timing chain issue is commonly associated with the GM 3.6L engine, it is more common in the LY7 version. The LY7 GM 3.6L engine was introduced in 2004 and has a 10.2:1 compression ratio. The engine is still in production to date.
The earlier versions of the LLT engine are also prone to this problem. Following numerous timing chain problems, GM upgraded the engines to address the issue. Cars using the GM 3.6L engine made in 2012 and onwards have fewer timing chain issues.
- Overconsumption of oil
Vehicles using the GM 3.6L are known to consume more than average when it comes to oil. Drivers must frequently replenish the oil to prevent the engine from depleting the oil, hence putting a strain on the timing chain tensioners.
If there is slack in the timing chain, then some teeth will be skipped, leading to the chain overstretching. Repairing this anomaly requires a lot of money.
There is a need to be vigilant to catch the running low oil problem in time. Several drivers have reported that the engine can run out of oil before the car even alerts the driver on the dashboard.
Many drivers have resulted in servicing their vehicles at 5000 miles or less. One needs to check the oil level frequently and also carry at least a quart of oil in the trunk just in case.
- Timing chain stretching
The camshaft and the crankshaft have a close correlation. If the timing chain stretches, this correction is affected. This causes the valves to open and close at the wrong time. The Engine Control Module (ECM), which closely monitors everything about the engine, will pick this anomaly in the valve opening and closing and trigger the CEL light.
This will probably be followed by the engine misfiring and, in extreme cases, stretching the chain so the engine won't start.
What causes timing chain problems in the GM 3.6L engine?
The GM 3.6L V6 engine is generally robust and a great performer. However, the timing chain issue is widely known such that when you ask in the online forums what to do with your faulty engine, a good number of people will advise you to just repair the car and sell it.
To understand the timing chain issue in this engine, we need to establish what causes it:
- Inadequate lubrication. The GM 3.6L engine is quite thirsty, and as such, it requires more oil than most V6 engines. Draining such oil should be done a lot more frequently too. Infrequent and inadequate oil in the engine means the engine runs on degraded oil. This means the whole system is inadequately lubricated, which then causes more than usual wearing out of parts. When this problem persists, the timing chain stretches in length and can even fail in some cases.
- There is a design fault that can be blamed on GM. General Motors changed the chain's design to a 7.7mm pitch from 9.5mm. In 2012, GM issued a memo where they offered a 'special adjustment timing chain wear' for cars running on the 3.6L engine. They went further to extend the timing chain warranty to 120,000 Miles, or 10 years whichever comes first.
- General Motors installed an Oil Life Monitor (OLM) in the earlier models of the 3.6L engine and calibrated it to allow for excessive mileage between oil changes. The company changed the mapping of the OLM to a shorter sequence. The problem seemed to drastically reduce in the newer models that were not using the OLM.
How do you know your car needs a new timing chain?
Because the GM 3.6L has been known to have timing chain issues, many drivers are on the lookout for any symptoms that indicate their car might have that issue. Many of the symptoms are easy to spot, but there are those that a mechanic can only identify. So, it is essential to ask your mechanic to help you pick some of the symptoms.
Here are the signs to look out for:
- Engine misfiring or runs poorly
- Metal shavings can be found in the oil
- The engine won't start, or it will just fail
- There is a ticking noise in the engine
- You'll notice more smoke and fumes than normal
- Check Engine Light (CEL) is on
- The engine starts acting up when the RPM reaches between 2000 and 4000
- There will be an oil leak at the front of the motor
- Engine rattles while idling
How to fix the GM 3.6L V6 engine timing chain issue
The timing chain issue has been persistent in the GM 3.6L engine. General Motors has repeatedly come forward to solve this issue but not to the satisfaction of all the customers. At one time, the company replaced the timing chain for free and, at other times, extended warranties on the engines.
In earlier days, GM even went in as far as making their oil spec called DexosI. Clearly, this never worked since the problem persisted.
Besides the company's numerous efforts to try and solve this issue, here are some of the things you can do to fix the problem:
- According to some drivers who have experience using the GM 3.6L engine, using oil with low NOACK helps keep the engine lubricated. Using a 5w-30 quality type of oil and changing every 5000 miles is said to help keep your timing chain intact.
- If the car shows the symptoms indicated earlier in the article, which include engine backfiring, CEL going on, and a ticking sound coming from the side of the engine, it is time to visit a mechanic. Check GM bullet in No 11340B released on 29th June 2012, which extended the engine's warranty to 10 years or 120,000 miles. The models covered were 2007-2009. The dealers will replace the timing chain, and all the repairs will be done for free.
- In some instances where the warranty has lapsed, you will need to gauge whether replacing the timing chain is practical or not. Replacing a timing chain in a GM 3.6L engine will cost you between $2000 and $ 3000. Buying a new engine will cost you around $7,000 or more. Given the risk of reoccurring timing chain problems, some car owners who have replaced the chain have sold their cars soon after. This raises a unique concern: many cars that run on this engine will be sold just before their warranties expire. This means new owners who buy these cars, many of whom without an idea of the problems dogging the vehicles will be in for a rude shock after only using the cars for a short time. General Motors should come up with a good solution to the timing chain issue because, much as the engine remains generally popular, the brand name can be tarnished by the bad PR the GM 3.6L gets.
FAQs
Has GM fix the 3.6 timing chain issue? ›
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.
Can you fix a timing chain without replacing it? ›Timing belts must be replaced on a regular basis, but timing chains do not. There's no reason to alter the timing chain unless it's damaged, strained, or otherwise affected.
What are the symptoms of timing being off? ›What causes ignition timing to be off? When any changes are made to the engine of a car, the ignition timing is adjusted accordingly. If not, you could experience several problems with your engine with improper ignition timing like knocking, hard to start, increase fuel usage, overheating, and reduced power.
How many hours does it take to fix a timing chain? ›During the combustion process inside the cylinders, camshafts open and close the intake and exhaust valves at just the right time. Overall, it should take a qualified mechanic between 5 and 8 hours to replace the timing chain and all of the parts that go with it.
Will timing chain throw a code? ›Hi there - yes, a worn or stretched timing chain, weak timing chain tensioner, or worn timing chain guides can cause misfiring, cam timing problem codes, low power and generally poor running of the engine. Most, if not all, of these problems will illuminate the Check Engine light.
What does a bad timing chain tensioner sound like? ›There is a rattling sound. A lax timing chain, or worse, a broken timing chain with loose parts within the engine, will produce a rattling sound when your car is idling. This rattling sound is typically most prominent while the engine heats up and disappears after some time.
How do I know if my timing chain is stretched? ›Signs of a Faulty Timing Chain
A common finding in a vehicle with a bad timing chain is unusual rattling noise when the engine is started or when brakes are engaged. It happens due to the loose or stretched timing chain that shakes and rattles while rotating when the engine motor is running.
Timing Chain vs Timing Belt. Timing belts require routine replacement—timing chains do not. Timing belts and timing chains both serve the same purpose—and that's to keep the camshaft(s) and crankshaft in sync. But there are differences.
What does a stretched timing chain sound like? ›Timing chain noise is commonly most noticeable during cold startup of the vehicle when oil pressure and oil flow is at its lowest. Excess slack in the timing chain can cause a rattling sound or even a clanking sound if the slack is severe enough to cause the chain to contact the timing chain cover.
Does timing chain affect acceleration? ›Over a period of time, the timing chain can stretch, which can cause the chain to skip a gear on the cam or crankshaft. This causes the engine's timing to fall out of calibration and often results in a misfire. The engine may also run poorly and lack accelerating power.
What happens if timing chain goes while driving? ›
A broken timing chain will cause an engine to not start or fail while driving. If the belt is already broken, the engine won't have enough compression to start. If it breaks or jumps while driving, the pistons will be damaged from contact with the valves. The valves themselves will bend and potentially ruin the engine.
What happens if you dont fix timing chain? ›If you don't replace the timing chain and it happens to break, then the engine can completely destroyed. Most engines today are “interference engines,” which means that the engine's valves move in and out of the same cylinder space as the pistons.
How long will a rattling timing chain last? ›Driving with a bad timing chain could give you serious engine damage, and it's also dangerous because it could cause your vehicle to stop suddenly without warning. A timing chain typically requires replacement anywhere from 40,000 to 150,000 miles.
Is there a sensor for timing chain? ›The sensor is actually a torque transducer that senses the net torque imparted to the timing sprocket by both sides of the timing chain. Prior to the introduction of this sensor, test engineers experienced great difficulty obtaining an accurate signal because of space limitations and the presence of high radial loads.
What problems can a timing chain cause? ›If the timing chain breaks while the engine is running, the engine will stop immediately and will likely bend valves and damage the pistons. The timing chain can also flail around inside engines and the loose ends may cause additional damage. It is not uncommon for this to damage the engine beyond repair.
Does harmonic balancer affect timing? ›The harmonic balancers found on many vehicles are constructed as two pieces of metal with a rubber layer in between to dampen the vibrations. If the layers separate or slip, the timing marks, which are usually stamped into the front of the pulley, can shift and thus throw off the placement of the timing marks.
Why does my timing chain rattle when I accelerate? ›At the point where the chain guides are worn beyond the ability of the hydraulic tensioner to take up the slack, the timing chain begins to rattle. This noise is caused by the timing chains becoming so loose that they whip back and forth against the guides and possibly the timing cover.
Can low oil cause a timing chain to stretch? ›These often result in the failure of timing chains and other engine components due to insufficient lubrication and oil contamination, the most common form of which is elongation (or stretching) of the chain past its factory set clearances.
How do I stop my timing chain from stretching? ›Regular maintenance and regular oil changes, using the correct oil, every 5,000 miles is the best way to combat timing chain stretch and failure.
What causes a timing chain to stretch? ›A series of links are connected by pins on which they pivot. Soot particles can lodge in the tiny clearances between the links and pins. They slowly scour the metal surfaces as the engine is running, enlarging the clearances. After a while, the timing chain stretches.
How do I know if I have a timing belt or chain checker? ›
In order to tell if your car has a timing belt or a timing chain the first thing you need to do is inspect your engine. Check the side of your engine, and if it has a tinplate or plastic cover, then you've got a timing belt. If your engine has neither of those, then it has a timing chain.
Has GM fixed lifter problems? ›There does not seem to be any repair to prevent the lifters from getting stuck and owners of the affected GM cars and trucks are placed into a position of waiting to see if they will become the victim of a faulty lifter resulting in a major engine failure.
Has GM fixed the oil consumption problem? ›According to allegations in the class action lawsuits, starting with some 2014 model vehicles, GM began implementing a Generation V Vortec 5300 engine that was redesigned to fix the excessive oil consumption of the Generation IV engines but did not resolve this issue.
Is the GM 3.6 VVT a good engine? ›Despite its rather lengthy list of problems, the GM 3.6 V6 is known to be quite bulletproof. The v6 power plant is powerful and tech-laden. Its Achilles heel though has to do with its engine oil changes.
What year did GM start variable valve timing? ›GM also patented an early system in 1975, but scrapped it due to lift problems. It was not until 1980 that a vehicle with VVT technology was made available for the North American market.
How do you stop a lifter from ticking? ›How Can You Quiet Your Car Engine? Once you verify the lifter ticking is not caused by a worn-out lifter or some other damaged part, the best thing to do is change the oil. Get rid of all the oil currently in the engine and flush it out before adding new oil.
How GM dealers handle engine valve lifter issues? ›If the customer has experienced prior valve lifter failures, dealers can choose one of three options: replace one bank of lifters and offer the customer a 60-month, 100,000-mile Powertrain Component Coverage Letter, replace the entire engine, or reach out to the District Manager of Aftersales for further guidance.
Is it worth fixing lifter tick? ›If your engine has a lifter tick, or tap, you need to have it fixed as soon as you can, because it can cause serious and expensive problems with your engine.
Is there a class action suit against GM? ›A California jury has ordered General Motors to pay $102.6 million to a class of consumers after finding that it hid an engine defect that caused problems including stalling and premature breakdown in tens of thousands of SUVs and trucks.
What are the 3 causes of oil consumption? ›- IMPROPER OR POOR-QUALITY OIL. Different engines require the use of specific lubricant blends. ...
- DAMAGED PISTON RINGS. ...
- OLD ENGINES. ...
- WORN SEALS OR GASKETS. ...
- BLUE SMOKE. ...
- LOW COMPRESSION. ...
- HIGH-CARBON FORMATION IN THE ENGINE. ...
- COOLANT DETERIORATION.
What years did Chevy have oil consumption problems? ›
The GM Generation IV Vortec 5300 LC9 gasoline engine has been the target of multiple lawsuits over the years due to alleged excessive oil consumption issues, with vehicles covered including the 2011- through 2014-model-year Chevy Avalanche, Chevy Suburban, Chevy Silverado, Chevy Tahoe, GMC Sierra, GMC Yukon, and GMC ...