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Chevy 6.6 Gas Problems : [ Common Issues & Solutions ]

Chevy 6.6 Gas Problems : [ Common Issues & Solutions ]

As a car owner or an automobile critic, you might have a distinct opinion about the Chevy 6.6L V8 gas engine. Well, the public view reveals some mixed feelings, and the engine looks pretty reliable on paper. However, it isn’t absolutely flawless when it comes to the practical ground. Some problems do come with it, particularly in controlled environments or tests.

It is for the common Chevy 6.6 gas problems that some critics consider Dodge and Ford engines to be better picks. So, if you own one of these branded cars, or are willing to purchase one, it makes sense to know the common glitches.

This way, you will make a calculated approach while purchasing the car. In brief, Chevy 6.6 seems to be quite reliable. However, the common issues with this engine include low power, knocking sound, weak engine transmission, and weak acceleration.

We have discussed the common Chevy 6.6 gas problems in this article.

Chevy 6.6 gas problems

Chevrolet introduced its 6.6 V8 engine after the Duramax ones. These engines feature an automatic transmission (6-speed). Gas engines traditionally offer better acceleration.

Car owners would usually expect the 6.6 engines to deliver better speed pickups, but that is not the case. The Duramax engines outperform the Chevy 6.6 gas engines as the latter has certain problems. Obviously, these gas problems imply a significant drawback for cars and trucks. Besides, these trucks tend to be excessively heavy.

1. Knocking sound

Chevy truck owners have reported a light knocking sound. Locating this noise turns out to be difficult. However, experts suspect that it comes from the transmission case.

Particularly, when you keep the truck idle or park it somewhere, you may hear this noise. Usually, you would come across this problem after you change the oil. So, you might encounter this issue after changing the oil for the first or second time.

Some drivers stated that they changed the first oil at 2,400 miles, when they noticed the knocking sound. They made the second oil change around 6,500 miles, when the sound again came back.

Poor valve springs and filters might lead to this problem. You can resolve this issue after you inspect the fuel line and the valve.

Some experts also believe that an oil issue leads to this noise. Therefore, they recommend switching to a synthetic oil of a better grade. However, you might have to drive your truck for around a thousand miles even after changing the oil, so that the noise completely vanishes.

You must note that the knocking sound issue bothers some Dodge and Ford truck owners as well.

2. Low power and authority

One of the most bothersome Chevy 6.6 gas problems is the lack of torque and horsepower. This hinders the ability of these trucks to tow heavy weights. When you compare this gas engine to the Duramax diesel engine, you would find that the former comes with lower torque and horsepower.

The Chevy Silverado HD 2020, for instance, comes with a turbo diesel engine. It is a 445-hp engine featuring 910 pound-feet of torque. The maximum towing capacity is around 36,000 pounds, which easily outperforms the gas engine trucks.

Big block and diesel engines deliver maximum torque when the RPM is low. Therefore, it would be a better decision to use them for towing.

The lack of power and authority is also evident from the weak acceleration of the trucks. They are very sluggish, even when you don’t load the trucks to their full towing capacity.

However, some users are satisfied with the acceleration and engine power of the gas engine. They hold the opinion that it performs pretty well, considering the standard parameters of a truck engine.

3. Slow acceleration

We have already mentioned that the slow acceleration of this gas engine often bothers the owners. This is why the online forums are loaded with negative comments about this engine.

The Duramax outperforms this engine in every department in terms of speed and acceleration.

Ultimately, slow acceleration would take a toll on your drive quality, as you would expect your truck to deliver the desired performance. There’s a lot of room for improvement if Chevy wants to bring the gas engine at the same level as the Duramax.

Depending on whether you want the Chevy as your work truck or a daily driver, you need to make the purchase decision. The acceleration issue is evident in the daily driver trucks.

Ultimately, you won’t find the agility that comes with gasoline engines in this one. No wonder, why critics have been harsh on Chevy as they are unhappy with the performance.

When you think of purchasing a truck, you cannot afford to overlook the speed. Therefore, slow acceleration continues to haunt the owners.

4. Low transmission speed

Well, the transmission speed could have been better in the 6.6-liter engine, considering what the competitors are offering to owners. Rather than the 6-speed transmission, experts believe that a 10-speed transmission would be a better integration for the engine.

However, even if the engine had a 10-speed transmission, the experience might not have been better. Problems would continue to haunt the owners due to the upshifts and downshifts.

Considering the six-speed option, the transmission in this Chevy engine isn’t the best. Evidently, the gas engine has plenty of room for improvement to impress the users.

5. Limited towing capacity

Although Chevy continues to be a celebrated brand, the low towing capacity of the 6.6-liter gas engine makes it a bad choice.

The towing capacity of this engine is only 5,000 pounds. it is adequate to pull a trailer or a boat. Even a small Chevy car can tow this weight, so you would want your truck to be a better hauler.

How good is the new 6.6 gas engine?

The gas engine of 6.6 liters from Chevy has some problems. Overall, it is decent and you might consider purchasing a truck with this engine. We have already explained the common issues that these gas engines come with. So, you shouldn’t have new surprises when you get one of these trucks.

In some forums, people have commended that even though Dodge or Ford performs better with their engines, they have a fascination for Chevy trucks.

In case you belong to this category, you can go for the purchase. If you are not too demanding in terms of acceleration or towing capacity, you can settle for a Chevy truck with the 6.6 gas engine.

What is the fuel mileage for a 6.6 gas engine?

You can expect around 18 mpg on highways from the 6.6-liter gas engine. On the other hand, this Chevy engine can deliver around 14 mpg in cities.

However, if you are hauling loads or towing, the mileage would be low. A positive side for the owners, you won’t need to invest in premium fuel for this engine. Regular gas would be sufficient for its optimal performance.

Now, if you compare the engine to Duramax, the latter needs premium fuel to achieve the promised mileage. This implies that the fuel charges for the owners of Duramax engines would be considerably higher.

Is the GMC 6.6 A good engine?

Yes, the GMC 6.6 is a good engine. For most truck owners, the engine power would be adequate. It is capable of towing a weight around 17,370 pounds.

So, if you are willing to carry your Yacht or tow any load, you can find a reliable engine in this one. Compared to the diesel engine, the gas engine turns out to be cheaper by around $10,000.

What transmission does the 6.6 gas have?

The 6.6-liter gas engines come with 6-speed automatic transmission. For a gas engine, you would expect better acceleration from it.


Considering the price, the Chevy 6.6 happens to be a decent pick. After all, it won’t cost you as much as a diesel engine. However, as an owner, you need to be prepared to encounter common problems from time to time.

While some users are not happy with Chevy due to these problems, others have prioritized the cost-effectiveness of the engine and opted for it over Ford or Dodge.

In reality, most of the Chevy 6.6 gas problems are minor issues. Fixing the flaws won’t drain your resources heavily. However, if you fail to address certain issues immediately, they might lead to some major problems. So, if you are ready to bear with these common issues, you might consider purchasing a gas engine truck from Chevy.