If you know Lifeonfour, then you know we love diesel engines, and we’re an authority when it comes to their problems. Today, we’re taking a look at a very specific diesel engine from GMC. The engine we will be discussing is the inline-6 GMC 3.0 diesel, that you’ll find in 2019+ Tahoe’s, Suburban’s, Cadillacs, etc.
Having done a good investigation on a car or a truck is always a good idea before you buy. And when it comes to trucks, there are a lot of things you have to be worried about. Especially the ones with diesel engines, which can be pretty expensive to fix since diesel do come with some really expensive components. But you shouldn’t worry because we are going to cover all about this GMC engine.
First, we are going to learn more about the specs of the 3.0 engine and then we will dive deeper into the GMC 3.0 diesel engine problems. Lastly, we will learn more about the reliability of this engine. So, let’s dive into the topic.
Basic GMC 3.0 Diesel Engine Specs
Before we dive into the GMC 3.0 diesel problems, let’s take a look at the specs of this engine. Specs are important, especially for those who are looking to buy a truck with one of these engines. So, let’s cover them briefly before we move on to the problems.
The GMC 3.0 engine is part of GM’s Duramax diesel family of engines. This engine was conceived as a fuel efficient engine intended to serve the purpose of being the workhorse for the full-size half-ton pickup trucks, as well as the full-size SUVs that GMC offers. We are talking about the GMC Sierra and the GMC Yukon. But more on the applications we will cover later on.
When it comes to the design of this engine, this is a proper modern diesel engine. It has six cylinders and a total displacement of 3.0L. The block is made out of cast aluminum alloy that is very strong and saves about 25% of the weight compared to cast iron.
The engine also has forged steel crankshaft and forged steel piston rods.
The cylinder head of this engine is DOHC which means that it implements a dual overhead camshaft layout. There are four valves per cylinder, two for the intake and two for the exhaust.
There are also a ton of modern diesel technologies such as DPF, EGR, common rail fuel injection, and a variable geometry turbo.
But here is the list of specs of this engine.
- Configuration: inline-6
- Displacement: 3.0L
- Bore: 84 mm
- Stroke: 90 mm
- Block & Head Material: Aluminum
- Head Design: DOHC, 4 valves per cylinder
- Compression Ratio: 15.0:1
- Turbocharger: Yes
- Fuel Injection: Common Rail
- Horsepower: 277 hp
- Torque: 460 lb-ft (623 N-m)
Common GMC 3.0 Diesel Engine Problems
Common problems with the GMC 3.0 diesel engine include:
- Crank Start Issues
- Injector Failure
- HPFP Failure
- EGR Failure
- DPF Failure
- Oil Pump Belt Problems
We learned more about the common problems of the GMC 3.0 diesel engine, now let’s move on and learn more about these problems in detail.
Crank Start Issues
The first and most common problem is a very odd issue that appears on these engines, especially the early engines. This is the problem when the engine continuously cranks and does not start or it starts eventually after long cranking.
This problem’s actual cause is not yet known, but many people assume that this is caused by the crankshaft position sensor or the wheel from which the sensor gets the reading.
Many people replace the wheel and call it a day, in many cases, this solved the problem. Some people solved the issues by adding a washer between the sensor and its mounting position in order for the sensor to get a proper reading.
Other possible causes according to GM include issues with the wiring harness, fuel pump, and other things that are very unlikely to trigger such a problem.
Although it is a really frustrating issue to deal with on a day-to-day basis. So, if the engine cranks a lot before starting, make sure that you stay away from it since it can be pretty expensive to fix.
Diesel fuel injector failures are another common problem that plagues the 3.0 GMC engine. These engines are using common rail diesel injection.
Common rail diesel injection uses very high-tech high-pressure diesel injectors that can often malfunction and cause problems.
They can fail in two ways, they can end up clogged or they can leak fuel. Both of these cases are a problem because you need a perfect spray pattern in order for your engine to work properly.
The solution to this problem is simple, you either rebuild the injectors or replace them. Rebuilding the injectors is far cheaper than replacing them because not only will you need to replace them, but you will also have to reprogram the new injectors to your engine. This means that the new injector will not work immediately on your engine.
These are basically some of the frustrating issues when it comes to owning a diesel engine. Now let’s move on to the next GMC 3.0 diesel problems.
The next problem on our list is the HPFP failure. So, what is an HPFP, and why does it fails? Well, HPFP is the high-pressure fuel pump.
This is the secondary fuel pump located in the engine bay. This HPFP is essential in order for the injectors to work well.
What this pump does is compress the fuel at the right pressure. But these pumps are notorious for failing and causing a ton of headaches for the owner.
They can fail in multiple ways, they can throw codes and check engine light, they can produce whining noises, and they can also leak fuel.
All of these situations mean that you have to replace this component. And replacements are not cheap since they cost a good penny.
Problems with the EGR on this engine are also quite common and can happen frequently. So, what is an EGR, and why is it a problem?
Well, the EGR is the Exhaust Gas Recirculation Valve. This is an emissions device that redirects some of the exhaust gasses into the intake manifold in order to cut down on NOx particles.
This EGR is very prone to develop carbon buildup and this carbon buildup will ruin the valve. Even if you clean it, it could still malfunction because it can fail internally.
That’s why regular cleaning is mandatory when it comes to these EGR valves in order to keep them in good condition.
Also, the EGR cooler can cause problems, it can crank and cause leaks to occur.
Common symptoms with this EGR system include rough idle, poor performance, bad emissions, limp mode, and check engine light.
The DPF can also be a problem on these GMC 3.0 engines. So, what is a DPF, and why is it a problem?
The DPF is the Diesel Particulate Filter, this is another emissions device but this device is installed on the exhaust system.
What the DPF does is collect the soot in its body and then when the DPF gets full, diesel is injected into the exhaust and this ignites the soot. This process is called DPF regeneration.
And what many people don’t know is that this regeneration has to be done when the DPF gets full.
You have to drive the car at higher RPMs over a 30-minute period on the highway in order to regenerate the DPF and bring it back to normal. Or else, it will clog up and cause problems.
In these cases, manual cleaning is the only way around the problem.
Oil Pump Belt Problems
The last problem on our list of issues with the 3.0 GMC engine is the oil pump belt problem. So, what is an oil pump belt, and why is it a problem?
Well, this is a special belt that is installed to drive the oil pump. This is a wet belt that is covered in engine oil.
The problem with this belt is that it has a limited lifespan, unlike the chains that were used previously for this purpose.
So, we can say that it is a terrible design. Not to mention that the transmission has to be removed in order to get to this belt and replace it. Which is a very expensive thing to do.
Which Models Have The GMC 3.0 Diesel?
The following GMC, Chevy, and Cadillac models can be fitted with the GMC 3.0 diesel engine:
- 2021 – Present GMC Yukon/Yukon XL
- 2019 – Present GMC Sierra 1500
- 2021 – Present Chevy Suburban
- 2021 – Present Chevy Tahoe
- 2019 – Present Chevy Silverado 1500
- 2021 – Present Cadillac Escalade/Escalade ESV
What Are The GMC 3.0 Diesel Problems?
Common problems with this engine include long crank issues, injector failures, HPFP failures, EGR and DPF clogging up, and oil pump belt problems.
Is The 3.0 GMC Diesel Reliable?
Yes, it is fairly reliable but it has its fair share of expensive parts that need to be replaced once they reach the end of their lifespan. This makes this engine very expensive to maintain because we are talking about thousands of dollars spent on repairs.