Duramax engines were created by a joint venture of Isuzu and General Motors in 2001. They replaced previous engines made in Detroit. They are known for their great power and torque performance ratings and overall reliability. But, some generations of Duramax engines are prone to several problems.
So, what year is Duramax to avoid? The first four generations of the Duramax engines, named LB7, LLY, LBZ, and LMM, are prone to some major problems. LB7 has a problem with the injection system. LLY has a problem with overheating and blown gaskets. LBZ pistons tend to crack if the engine has added horsepower. The cracked pistons also plague the LMM. These engines were made between 2001. and 2010.
Does this mean that these engines are bad? Well, no. If they are used and maintained properly, they will serve you great for a long time. Stay with us because we will go into detail regarding all these engines. Duramax engines are amongst the most popular diesel engines, and there are a lot of reasons for that.
Table of Contents
1.What is Duramax?
2.Common Problems with Duramax
3.What Year Duramax to Avoid
4.Duramax Maintenance and Care
5.FAQs
What is Duramax?
This 6.6-Liter V8 engine has a block of cast gray iron and a deep skirt design. Its robust design is made for heavy-duty work. Two upper inches of each cylinder bore were hardened to resist cylinder wall wear.
The rest of the internal components were created to be lightweight but at the same time, durable and robust. The crankshaft’s durability is increased so it can withstand high temperatures.
Connecting rods are made from forged steel and can endure high horsepower loads. Another innovative feature is the use of a high-power Bosch CP3 fuel injection pump that uses Common Rail technology.
A frequent problem of older Duramax engines is the lack of a fuel lift pump. Stock engines didn’t have problems with the lack of a lift pump. But, if you wanted to add some power to the engine, lack of high-pressure fuel became a problem. Injectors were in problem, and these engines required installing a lift pump.
From the L5P engine, all Duramax engines have a factory lift pump.
Advantages and Disadvantages of Duramax
From their creation, Duramax engines were praised for their high-power characteristics. They deliver a lot of horsepower and torque and, overall are good engines. They also withstand upgrades. You can upgrade a stock engine and double its power. Duramax engines are known as durable engines that can last over 300k miles.
Today there are a lot of all types of Duramax engines out there. That means that you don’t need to worry about parts. Also, most of the mechanics have a lot of experience with all-generation Duramax engines. You don’t need to think about finding a good Duramax mechanic.
The most common problems with Duramax engines are the fuel system and overheating.
Common Problems with Duramax
Although the Duramax engine is known as reliable, you should try some Duramax years to avoid it. We cannot say that these engines are the worst Duramax engines. They are still overall good engines. Duramax engine owners know these machines’ reliability, but they still have some common problems.
Correlation Between Problematic Years and Duramax Engines
The first generation of Duramax engines, the LB7, had a problem with fuel injectors and a water pump. Head gaskets and pistons are also a problem. Fuel filter housing O-rings caused fuel leaking.
The company’s second-generation engine, the LLY, and the connecting rods couldn’t handle any major upgrades. The large turbo made problems for the head gaskets. The EGR valve issues also often caused problems with overall engine performance. Glow plug failure remained a problem. Fuel pressure relief valve can also cause problems.
The third generation Duramax, the LBZ, had similar problems to the previous model. Add to that leakage from the transmission lines, and you know all you need to know about these engines.
The final Duramax years to avoid are those made between 2007 and 2010, the LMM. Low fuel rail pressure, the EGR valve, pistons, and the crankshaft are still a problem. Add to these the problems with the diesel particulate filter, and you know all the problems with the LMM.
What Year Duramax to Avoid
These engines are not bad; they have issues that need to be dealt with. Don’t write off these engines altogether. An average Duramax is an excellent engine.
LB7 2001-2004
LB7 Duramax engine that was made between 2001. and 2004. has a problem with the fuel injector failure. Most of the original owners changed the injectors while under warranty. But if you are buying a used LB7 check for this information. The injectors should be replaced with around 100k miles on the clock.
Duramax LB7 also has problems with fuel filter housing O-rings. This problem can result in a fuel leak and air entering the fuel system. This is a minor issue that can be easily fixed.
The water pump is another thing to look out for in Duramax LB7 diesel engines. They use a plastic impeller that is less durable than the iron one. It will deteriorate and cause a leak. That will result in lower coolant levels and frequent overheating.
Also, head gasket failures are not uncommon for an LB7 engine. This usually doesn’t happen before 100k miles on the clock, but be wary. These problems happen because of the poor head gasket design.
These gaskets are made from layered steel. During the compression stroke, the head sometimes lifts a little. This results in gaps in head gaskets. This will lead to leaks, and then coolant will reach the cylinders.
LLY 2004-2006
The next generation of Duramax diesel engines is the LLY. It shares some of the problems with the LB7 but has some unique problems.
LLY was a great engine back in the day, but today it looks like the time has passed over it. But, with a little upgrade, diesel engine enthusiasts can pull out a lot of power. There comes the first problem. When upgrading the LLY engines, bent rods tend to be a common problem.
When you pass a 500-wheel horsepower mark, the rods are a problem. These rods are very lightweight, making them susceptible to bending. You can either replace the stock rods or keep the upgrades at a minimum.
The LLY Duramax engine has the largest stock turbo of all Duramax engines. It also has the largest compressor wheel and the tallest exhaust vanes. This makes the turbo very powerful, which is great for the engine’s overall power. On the other hand, this is not so great for the head gaskets.
Over time head gaskets due to high temperatures and pressure, deteriorate. If the head gaskets are in trouble, you will notice the white smoke coming out of the tailpipe, coolant leaks, and engine overheating. Fixing the head gasket problem can cost up to $4,000. This will trigger a check engine light and will cause engine failure if ignored.
If you have problems with rough idling, misfiring, and overall poor performance, then you have a problem with the EGR. This engine is the first among Duramax models with the EGR. The EGR conducts exhaust gas recirculation to reduce nitrogen oxide levels in the atmosphere. When the EGR system becomes worn, it lowers the engine’s performance and makes it hard even to work.
Also, Duramax LLY is plagued with overheating problems. All Duramax made before 2006 have smaller radiators and cooling fans. Added heat combined with these smaller cooling systems components often leads to overheating in these diesel engines.
The fuel pressure release valve is another common problem in this Duramax engine. On the fuel rail is the pressure release valve, and it releases pressure when it becomes too high. Frequent use of this valve wears it down, leading to releasing pressure when it shouldn’t.
If you notice a sudden drop in power and a decrease in performance, you should check the fuel pressure release valve.
Problems with glow plugs are also something that you should turn a blind eye to. In Duramax LLY, the glow plugs are paired with problematic glow plug modules. Glow plugs modules often overload the plugs with the current. That can cause the plugs to break off, causing massive engine damage.
To fix this problem, it is enough to reprogram the module. Most dealerships do this for free. Most of these engines have this problem resolved. Nonetheless, pay attention to this issue when buying an LLY engine.
Check Out Common Issues with LLY Duramax Diesel 6.6 (2004.5-2006):
LBZ 2006-2007
LBZ Duramax shares some of the problems with its predecessor. The problem with the glow plugs, the water pump, the EGR valve, and the head gasket remains. These Duramax model years also have a problem with transmission line leaks and piston cracking issues.
The problem with cracked pistons usually happens in the first 100k miles. To avoid problems with pistons, you should use quality fuel and coolant liquid. You will know that you have a piston problem if too many exhaust gasses come out of the tailpipe. Also, a drop in performance is another symptom.
There are several moving parts in the transmission system. If any of them are worn or damaged, that will cause a leak. The transmission leakage is seen under the truck. Don’t forget to resolve this issue because, without fluid, the transmission cannot work.
LMM 2007-2010
Several issues from previous versions and older engines remained in the LMM engine. The most common are piston failure, leaky transmission leaks, crankshaft failure, and low fuel rail pressure.
The new component in the LMM Duramax engine is the diesel particulate filter. Every diesel engine needs to fulfill high diesel emission standards. The DPF is there to capture the diesel particulates that would usually go into the atmosphere.
The second part of the diesel particulate filter is the active regeneration system. It is used to burn off all the particulates caught by the DPF. That regeneration cycle is set to around 700 miles. When the time comes, owners must drive around 40 miles in highway conditions. That resolves the build-up in the DPF filter.
If the truck is driven in city conditions in these periods, the DPF filter cannot get hot enough to unclog. This causes excessive regeneration which can cause different engine and DPF problems. You can avoid this by simply driving on the highway during this period.
Duramax Maintenance and Care
Duramax engines and their pickup trucks require proper maintenance, which is key to keeping them in good condition. Also, pay attention when upgrading the exhaust system. Allow the engine to breathe freely.
Tips on Maintaining and Taking Care of Duramax
- Use a straight pipe, so the engine can breathe better
- Get an EGR plate to prevent black tar from entering the intake
- Use a high-quality synthetic oil
- Always use good fuel with additives for lubricity
- Change the fuel filter every 8000 miles
- Change the oil filter by the book
- Clean or replace the air filter regularly.
Ways to Prolong the Life of Duramax Engine
Always look for strange symptoms, like stalling and a drop in performance. This can be a sign of a big problem. Don’t wait to drive your truck to the mechanic if you notice any leaks.
FAQs
What Year Has The Best Duramax?
The best Duramax engines were made between 2011 and 2021. Those include the LML, LM2, L5P, LGH, XLD 25, XLD 28, and LWN.
Which Duramax is the Most Dependable?
Any Duramax engine made after 2010 is highly dependable. Choosing between LGL, L5P, LML, or LM2 is not a problem. They are all good engines.
How Long is a Duramax Diesel Expected to Last?
A Duramax engine is expected to last over 300k miles with regular maintenance. There are reports from many owners that Duramax engines can last over 500k miles. This means that these engines are highly reliable with long work life.
What is the best year of the Chevy 2500 in the Duramax?
Two generations of Duramax models stand out for a Chevy 2500: LBZ and LML. The LBZ was made between 2006 and 2007, and when major problems are resolved, you get a great engine. The LML was made between 2011 and 2016 and is a proven Duramax engine.
These engines are recommended for a wide range of cars, including GMC Sierra, Chevrolet Silverado HD, Chevrolet Kodiak, and other GM trucks.
What Duramax has head gasket problems?
The first three generations of Duramax engines, the LB7, LBZ, and LLY, had problems with head gaskets.
Final Considerations
GM started a revolution in 2001 when they introduced Duramax diesel engines, these engines proved their worth and are still very popular in used vehicles. They are easy to maintain and upgrade and are very reliable.
Still, all these engines have their problems. We recapitulate all the major issues with the older engines. Many components may seem to cause a problem depending on the model years. But these problems can be solved.
We mentioned all these issues so you can know what to look out for when buying a used truck. When you choose a good truck, you can be sure that you got a great Chevy that will serve you for years to come.
