6.6 Duramax V8 Diesel Problems – Customers’ Complaints and Reviews

Although the 6.6-liter Duramax is sometimes called the best diesel engine in the Chevy lineup, we often get bad reviews and opinions from very irritated owners. We've decided to write a full article describing the most common issues and problems your Duramax diesel engine may have. We've also talked to mechanics and asked which problems of these engines they have to repair most often.

Today, we'll tell you about all the common problems of the 6.6 Duramax diesel engine. Unfortunately, these engines are not ideal and they still have their issues. We've investigated some forums and spoken to owners in order to provide you with the most up-to-date and fair information about this engine and its drawbacks.

Key features and my opinion about the engine

• Production years:2001-now
• Average lifespan of Duramax V8:240,000-280,000 miles
• Fuel supply type:Common Rail
• Power range:250-550 hp
• Fuel efficiency:average
• Engine block material:cast-iron
• Engine reliability score:medium
• The most common problems:DPF and EGR problems, weak sensors, injectors contamination, fuel pump problems.

What good things do we know about the 6.6 Duramax V8?

It's a very efficient engine. If you count up the amount of energy it produces from, let's say, one gallon of diesel, you will see that the engine is super-efficient. This means that you will burn less fuel for making the same distance as with many other diesel engines. The eventual mpg depends on the vehicle, but it's impressively good.

This engine can live long and it has just a couple of minor problems that will probably bother every owner. Overall, the 6.6 Duramax is one of the best big-displacement diesel engines in America. Yes, the competition is not very dense, but still, this is a very important thing to remember.

Here are some other advantages of the 6.6 L engine:

• it's one of the best engines for towing trailers, even small Duramax diesel engines are good, but the 6.6-liter one is just a beast;
• overall durability - the engine is reliable and it will not break now and then, it won't make you go to specialists every week;
• the engine is relatively comfortable, it doesn't vibrate as much as smaller diesel units and it doesn't produce a lot of sounds;
• the 6.6L Duramax is still thought to be quite an eco-friendly engine, as far as it can be with its displacement;
• the engine offers wonderful acceleration for a diesel unit - hard to say exactly because it depends on the vehicle type;
• the engine was engineered by Isuzu, it was first introduced in 2001 and it's still in production which is a surprisingly long life.

The Duramax V8 engine has a relatively simple OHV construction, its block is made of iron. It can be repaired even after fatal failures. The engine is equipped with a simple Garett turbocharger. The injection system is common-rail. It's not that simple and it will take some money from you when it's broken. But still, it's not the worst solution.

Well, it's a fairly good engine that has no weak points if you just look at the specs. But once you start researching forums and reviews, you will see that things are a little worse than they seemed to be just a moment ago. As with any engine in this world, the 6.6 Duramax has some problems and we need to know about them.

What are the main problems of the 6.6 Duramax diesel?

The durability and reliability of this unit don't change the fact that it has some common issues. They are not fatal and these engines are still good. We want you to hear this - we don't think the Duramax is a weak series of engines.

Here are some of the main issues you can have.

1) Fuel pump problems

Nearly all diesel engines will have some problems with fuel supply once they reach a certain mileage. High-mileage engines will just kill your budget with their fuel pump problems. This is true for the 6.6 Duramax because it uses expensive injectors and it needs high pressure of diesel fuel to work properly. The high-pressure pump is likely to fail every 60,000 miles or something like that.

It doesn't mean you will not be able to repair it. Replacing the pump solves all the problems. But this will take a lot of money from your pocket. Unfortunately, finding a good mechanic who can help you with this is as hard as finding good parts.

2) Fuel injector issues

The 6.6 Duramax engine is known to have a lot of issues with injectors. The common-rail system is controlled by Bosch equipment and it's not bad. At least, for the first 100,000 miles. After that you have two choices: you may keep on driving your vehicle with OEM parts and repair them every 10,000 miles. Or you can forget about it and replace the common-rail system to get it going for another 100,000 miles.

The biggest problem is the price. You may kiss goodbye thousands of dollars to get your vehicle back on track.

3) Leaks

As with any engine with high pressure of oil and fuel, the 6.6 Duramax will leak oil from every second seal and gasket. We know about head gasket problems. Also, the fuel filter O-ring may leak fuel. One more possible place for a coolant leak is the water pump.

Repairing your engine after it started leaking is not a very hard task. All you need to do is to replace a certain seal, ring, or gasket that is leaking. After that, you'll be ready to drive more miles with no problems.

Leaks should be treated right when they occur because they may lead to low levels of oil or coolant.

4) Overheating problems

Diesel engines do not tend to overheat. But the 6.6 Duramax may surprise you. One of the most important things to watch out for is the coolant level. With the low level of antifreeze, your Duramax may start boiling and it will cause big problems with the engine in the end.

Overheating may also be caused by problems with the thermostat. It should work properly in order to avoid coolant circulation in a small circle without getting to the main radiator. If the thermostat is stuck, it may cause problems.

5) Turbocharger issues

This is a high-mileage problem but you still need to consider it. The 6.6 Duramax engine has a simple turbocharger, so it will not bother you up until 200,000 miles. But everything has its own lifespan, and at this mileage, your turbo will probably need replacement or a solid repair.

Some symptoms of a failing turbocharger are as follows: loss of power, black smoke from the exhaust pipe, high fuel consumption, check-engine light, excessive oil consumption, etc. If you experience these problems in your vehicle, it may be the best time to go and check the turbocharger.

How to avoid problems with the 6.6 Duramax V8?

This engine can go up to 300,000 miles if you maintain it properly. If it's poorly maintained, the engine may die at about 180,000 miles or even sooner. Under the good maintenance, we understand regular oil and filter changes, good liquids and fluids for your vehicle, and solving problems when they come.

It's important to know a specialist who can diagnose your engine, help maintain it, and also repair it if needed.

Here are some of the most important factors that prolong the 6.6 Duramax's lifespan:

• good oil - use the oil that is recommended by Chevy for this engine, otherwise, the longevity will be questioned;
• regular maintenance - this is a simple tip but it helps owners drive their vehicles with Duramax engines for decades;
• only high-quality fuel - cheap diesel fuel with unknown background is not an option for you if you have the vehicle equipped with this engine;
• no revving up - the highest RPM for the 6.6 Duramax engine is 3450 rotations, the unit doesn't love being revved up like crazy;
• regular diagnostics - find a mechanic who will diagnose this engine once a year and see if it can go another year with no problems.

We've included all simple rules on this list and they will help you prolong the lifespan of your vehicle. It's not very hard to make sure that the engine can run another ten thousand miles. You just need to take it to a specialist. Unfortunately, the 6.6 Duramax is not that simple to perform all the repair and maintenance procedures on your own in your garage.

Final words

If you own or are planning to buy a vehicle equipped with the 6.6 Duramax engine, you should read this article carefully. Yes, this is a pretty good and durable engine that can be called the best in its sphere. But it still has some problems and issues you need to know about.

We've tried and gathered all the information we could get online. Also, we've spoken to mechanics and to owners of a vehicle equipped with the 6.6L Duramax diesel engines. We hope the guide of problems and solutions that we've created above will help you sort out your thoughts about this wonderful engine.