GMC 6.2 Engine Problems

GMC 6.2 Engine Problems – Are They That Serious?

Are you planning on purchasing a GMC Yukon or a Sierra and you want to properly inform yourself about this engine before you make a purchase? If this is the case and you want a GMC product really bad then you came up to the right place because there will be a lot to cover on the GMC 6.2 engine problems and more.

Getting yourself properly informed before you make a purchase on basically anything, you need to do good and thorough research because car shopping is not grocery shopping. Cars cost a lot of money and for many of us means the whole world. So, getting the right one is key if you want to have happy and fulfilling ownership with a good time spent.

And the engine is one of the most important aspects when purchasing a new or used vehicle. The engine is basically the heart of the vehicle and with this engine, you are able to run the car. If the engine performs rather well, your ownership will be trouble-free in most cases. But if it doesn’t then you probably going to have some problems that will cost you an arm and a leg to repair. That’s why we are going to help you out by covering the most common problems with this engine.

First, we will learn the basics of this engine and its specs. Then we will cover the applications of the 6.2 engine and then we are going to elaborate on the GMC 6.2 engine problems and estimate if it is a good deal or not. So, if you want to learn more, follow along till the end.

6.2L V8

So what is the GMC 6.2 engine? This engine in fact is not a GMC engine but a Chevy engine that is shared between General Motors products and marques like GMC, Cadillac, and Chevrolet.

The 6.2 engine was launched as a replacement for the Gen IV Vortec. This engine as you know is a V8 engine with a pushrod design. Who said that pushrods are dead? They are still beating strong and are real workhorses of the American economy.

This generation of this V8 engine is also known as EcoTec3. It is mainly a truck engine but can be also found in other applications such as SUVs and even sports cars like the Corvette.

As you know, the EcoTec3 engines that are 6.2 liter have separate designations. There is the LT1 used in the Corvette C7 and the Camaro, the LT2 used in the Corvette C8. The LT4 is used in the Corvette ZO6, Camaro ZL1, and other high-performance products as well as the LT5 which is one of the most powerful engines out there pushing 755hp on the Corvette ZR1.

But the designations that we need in this case are the L86/L87. These are the engines that we focus on in this article and we want to elaborate on them for you to learn if they are a good deal or not. And these engines are truck engines. Used primarily in the Silverado/Sierra, Tahoe/Yukon, Escalade/Suburban.

Any of these vehicles produced since 2014 up until now have these engines. The L86 is the older version while the L87 is the newly upgraded version. But more on the GMC 6.2 problems a bit later after we cover the specs.

GMC 6.2 Specs

Now let’s discuss the specifications of the L86/L87 also known as the 6.2. After we finish we will cover the applications and later we will focus on the GMC 6.2 engine problems. So, let’s get into it.

These engines feature an all-aluminum block. Meaning that they are quite lightweight. But still, they use cast iron cylinder sleeves. This is quite essential since there is a lot of compression inside the cylinders. So, you wouldn’t want to rely on aluminum for this purpose. Although aluminum is a strong metal, it still can break. That’s why cast iron cylinder sleeves were used. The cylinders are positioned at a 90-degree angle like most classic pushrod designs.

This engine has a bore of 103.25mm and a stroke of 92mm. This is something that is shared with all of the Gen 5 blocks like the LT1, LT2, etc.

This engine uses the classic pushrod design meaning that this engine doesn’t implement an overhead camshaft like more modern V8 engines but it still relies on the old design. But although it is an old design, it is far more reliable as well as way cheaper. Meaning that this engine can be made for cheaper and is also quite cheaper to maintain.

The engine uses aluminum heads with direct injection. The direct injection causes some of the GMC 6.2 engine problems that we are going to elaborate on later.

What is interesting about this engine is that it implements an AFM. Also known as active fuel management, or displacement on demand. Meaning that some of the cylinders can turn off so the engine can save some fuel.

The power numbers of the 6.2 engine are 420hp and 460 lb-ft of torque. Now let’s discuss some of the applications.


So, what are the applications where you can find this engine in the first place? Where you could find the GMC 6.2 L86/L87 engine? The answer is that you can only find the 6.2 engine in Chevy, GMC, and Cadillac applications, and is often used to power only trucks and SUVs.

It is used primarily in the GMC Sierra and the Chevy Silverado. As you know, these are some of the best-selling GM trucks out there. Either they look different, under the skin it is basically the same truck. They share the 6.2 engine and have about the same power numbers.

Other products that use the 6.2 are the GMC Yukon, Chevy Tahoe, and the Cadillac Escalade. These are the SUV options that GM is offering. Similar to the pickup lineup they are also sharing the same componentry. Even though the GMC and Escalade are somewhat more luxurious than the Tahoe. So, you can expect the maintenance cost for these vehicles to be quite high.

This is because they are luxury items. Luxury items are always on the higher end, whether it comes to purchasing them in the first place or maintaining them.

So, overall, these are the applications that you need to pay attention to if you want to get the 6.2L engine. But remember that this engine is only available in vehicles above the year 2014. In earlier GM models there was used the Gen IV GM engines.

But what about the GMC 6.2 engine problems? Well, we are going to elaborate on all of the different problems in the following chapters where we will separate a chapter for each of them. And when we finish we are going to give our reliability score on this engine and determine if it’s a good purchase or not.

GMC 6.2 Engine Problems

Now let’s discuss the GMC 6.2 engine problems. Knowing them will be a lifesaver for you if you are planning on purchasing a GMC or a similar GM product to the ones that we listed above.

GMC 6.2 Engine Problems

What is worth noting is that we will go in-depth with each of the problems and we will learn which of these problems are easy to fix and which of the GMC 6.2 engine problems are more difficult and expensive to solve. So, let’s dive into the problems.

GMC 6.2 Engine Problems, Problems #1. Lifters Collapsing Causing Bent Pushrods

Do you remember that we covered the AFM or also known as Active Fuel Management also known as the thing when 4 cylinders are shutting down in order to improve the fuel economy? Well, this system is troubling this engine by a big margin. Don’t understand me wrong. I really like the idea of this system but the thing is that it doesn’t work that well in practice.

It makes some damage to the pushrods of the engine. This system works with the help of some complex lifters that are not seen in other similar products out there and these lifters serve the purpose of deactivating the 4 cylinders and turning your engine into a V4.

Sometimes the lifters collapse and cause the problem of bent pushrods. When this problem happens you will be aware of it. Since you will be down on power and the engine will not be happy at all.

The only solution would be replacing these lifters as well as the pushrods that were damaged. This is often covered under warranty if it happens on relatively low mileage. But if you are buying an older GMC or Chevy, this problem might be a big deal since it is rather expensive to fix. It will probably cost you more than a grand to sort it out.

Also, there are people that are disabling this AFM thing and driving it like that. There is also the option to delete it completely. This route is more expensive. But it’s the only way that you will get rid of these problems once and for all. Now let’s move on to the other GMC 6.2 engine problems.

GMC 6.2 Engine Problems, Problems #2. Excessive Carbon Buildup

The carbon buildup is another in the line of GMC 6.2 engine problems that pisses owners off. So why the hell this carbon is building up inside of your engine? Well, the answer is simple, direct injection. The direct injection system is making this carbon buildup a real menace in these engines.

The old LS engines were using port injection, the fuel delivery was not so precise, but it was good enough to clean off the intake ports. Now in this generation of the 6.2, the fuel is dumped in by direct injections. This means that the ports of these engines are not cleaned as they used to be in the older design.

And over the course of 60,000 miles, your intake valves will be completely clogged up. This clogging up can be so bad that it could basically ruin the performance of the truck or a car. Many cars also have this system on them.

The point is that with these systems the benefits are rather small but the downsides are rather big. The only way around this problem would be to clean your intake valves with a method called walnut blasting or take it to a dealership and let them clean it off with their special machines. You will end up paying a hefty fee of about $500 or even more in some cases. But at least you will be safe for another 60,000 miles.

Just make sure that you fix these GMC 6.2 engine problems on time. You don’t want to leave it like this and the valves to get damaged. Then the repair will be even more expensive.

GMC 6.2 Engine Problems, Problems #3. Direct Injection Pump And Injectors Failure

Another downside of the direct injection system of this engine that attributes the GMC 6.2 engine problems to be more expensive is the direct injection pump and injectors to fail.

These things work with absolutely zero tolerance. So, if you put some gas that has even tiny microscopic impurities, it will fail. So, if you have this engine or you plan to purchase one, you need to investigate the injectors as well as the fuel pump if they are working fine.

GMC 6.2 Engine Problems

If they are not working fine, it will cost quite a bit of money to get this thing sorted out. $2,000 in best-case scenarios. So, you need to be fully aware of these things and not step on a rotten floor. Make sure that the GMC or Chevy is sorted out when it comes to these components because fixing them is a rather expensive business. Now let’s move to other smaller GMC 6.2 engine problems that also can be frustrating to solve.

GMC 6.2 Engine Problems, Problems #4. Intake Manifold Gaskets That Leak

There is also a problem with higher mileage GMC products with the 6.2 engine that often have problems with the intake manifold gaskets. This problem is happening because the material that these gaskets are made out of becomes hard and it doesn’t seal well.

When there is not enough of a good seal in the intake manifold, there is a lot of unmetered air that is entering inside of the engine. Meaning that you will often see a check engine light as well as other notifications that something is wrong. The engine precisely will not be very happy with this work.

Since there is unmetered air into the combustion the engine will run lean and will have the trouble of keeping up. So, the computer will dump more fuel which will worsen your fuel economy.

What is good about this problem is that it is not that expensive to fix and you can do it by yourself. The intake manifold gasket is on top of the engine and you only have to remove a few components to get to it. Now let’s move on to other GMC 6.2 engine problems. Since there is a lot to cover still.

GMC 6.2 Engine Problems, Problems #5. Broken Exhaust Manifold Bolts

And the last of the GMC 6.2 engine problems that we are going to cover is the broken exhaust manifold bolts. The bolts on the 6.2 are often to break like on many truck engines out there and they are a pain to be replaced.

What is bad though is that you have to replace them if you want to fix that exhaust leak. These leaks can be really frustrating to deal with since gases can get inside of your cabin as well as other problems like check engine lights on the dash.

The check engine is often activated because of the O2 sensor that is getting some wrong readings and turns on the alarm in the ECU that something is wrong. Another symptom that often happens with broken exhaust manifold bolts is the hissing sound. You will hear a hiss coming from the front when the engine is working. This means that the exhaust engine is leaking.

The repair for this problem would probably be rather expensive since a lot of components have to come off for the mechanic to have the ability to reach the engine. You cannot expect to get this sorted under a grand since there is so much work.

And here we end our list of GMC 6.2 engine problems. These are the things that you need to be aware of when it comes to this engine. Now let’s discuss the overall reliability of the engine.

GMC 6.2 Engine Reliability

We have covered the GMC 6.2 engine problems and now let’s see the overall reliability. When it comes to reliability we can conclude that the 6.2 engine is a reliable engine after all. This engine is not a bad engine by any means. It is really good and deserves to be one of the top picks when it comes to picking an engine for their future truck.

On a scale of 1 to 5, when it comes to reliability, we will give the GMC 6.2 engine a solid 4. When it comes to the longevity of the block you shouldn’t worry about it much since it is a really proven design that is like nothing else out there.

But sometimes everything is in the little things like the AFM system that often breaks and bends the pushrods. To fix this problem you are going to need to replace the damaged lifter as well as the pushrod.

Another drawback is the direct injection system that creates carbon buildup in the intake ports. In addition to this, these injectors are also known to break from bad fuel and cause many headaches. They are really expensive to replace. So, if you are in the market for a GMC and you are learning the GMC 6.2 engine problems. This should be your top priority.

The AFM system luckily can be turned off, so you can consider this problem to be solved. The injectors and fuel pump should be your top priority when it comes to GMC 6.2 engine problems. Now let’s take a look at some of the alternatives.

GMC 6.2 Engine Alternatives

We have covered the GMC 6.2 engine problems. Now let’s take a look at some of the alternatives. And the alternative that you will probably look at is the RAM and its 6.4L Hemi.

The 6.4L Hemi is an engine of similar size and specs. Even though it is a bit less power than the GMC 6.2. This engine is also another great option if you are in the market for a truck. But this doesn’t mean that this engine doesn’t have problems.

The main problems with this engine are the issues with the MDS. This is Chrysler’s own AFM. Meaning that these cylinders that are shut off suffer from some poor lubrication. But luckily this system can also be turned off like the AFM.

Then there is the famous HEMI ticking sound that often appears on higher mileage engines that are well above 100,000 miles. This isn’t a big problem though since it is a minor sound.

Then there is also the problem with the HEMI misfiring. This issue is caused by the 16 spark plugs that are on this engine. Double that of the GMC 6.2 engine. Meaning that you will have to do more frequent spark plug changes. Overall, that’s no big issue with this engine. The problems of the 6.4 HEMI are rather smaller than the GMC 6.2 engine problems though.

GMC 6.2 Engine Problems Essential Knowledge

  1. The 6.2-liter EcoTec3 V8 is the most popular engine found in Chevy’s Silverado trucks and is also used in Corvettes, Camaro SS models, and big SUVs.
  2. The engine has six variations, with some having more problems than others.
  3. Direct fuel injection, a main design feature of the EcoTec3 V8, causes carbon build-up in the intake ports, resulting in poor idling, inferior acceleration, engine misfiring, and richer fuel charges.
  4. All direct-injection engine designs have this problem, which typically develops around 75,000 miles on the ticker.
  5. An oil catch can system can help lessen the carbon build-up problem by sloughing off excess oil and depositing it into the can in the engine compartment.
  6. EcoTec3 V8 lifter collapse can happen due to the active fuel management system, resulting in impaired driveability, but is usually covered by an extended warranty.
  7. The A8 automatic eight-speed transmission, which is used with most all 6.2-liter EcoTec3 engines, can experience problems, such as engine vibrations, shuddering, and rough gear changes from First to Second and when shifting down from Second to First.
  8. Moisture in the transmission fluid used in assembly is blamed for the A8 automatic transmission issues, and technicians should flush the system and replace the filter to fix it.
  9. Smaller problems that occasionally occur include fuel injector and fuel pump malfunctioning, splitting engine mounts, broken manifold bolts, and lower intake manifold gaskets failing.
  10. To lessen potential problems associated with the 6.2-liter EcoTec3 V8 engine, it may be helpful to invest in an oil catch can system and to regularly maintain the transmission fluid.

GMC 6.2 Engine Problems

In Conclusion…

In this article, we have covered quite a bit when it comes to the GMC 6.2 engine problems. First, we learned what is the 6.2 engine and some of the basics when it comes to it. Then we covered its specs and we indicated that is a truck engine. After, we learned the applications of the 6.2 engine.

Then we elaborated in-depth on the GMC 6.2 engine problems and we learned all about them. The most notable problems with this engine are the issues with the AFM system as well as the carbon deposits on the intake runners caused by the direct injection system. And lastly the problems with the fuel pump and injectors. Overall, not a big issue on the overall reliability of this engine.


  • Benjamin Ritchie Says

    The info on the hemi 6.4 being more hp and torque then gm’s 6.2is wrong. Hemi is 410/429 where gm that’s actually underrated is 420/460. Just wanted to correct that was all. If you drive either or you fell a big difference. Gm 6.2 aside for dfm issues is a very stout motor. Also carbon on the intake valves has been virtually eliminated with updated valve cover and valley breathing on the L87 design. I had a previous L86 and it didn’t seem a issue either.

  • David A Ball Sr Says

    2022 High Country 6.2 ourchased November of 2022 New. ar 3k miles the fuel injectors needed to be replaced nd at 8115 miles (August 10 months of ownership) blown lifters

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