LMM Duramax was launched in 2007 and ended its journey in 2011.
The engine is similar to the well-known LBZ.
It provides a very reliable and satisfying service.
Though it is a reliable engine, it has some common problems.
These problems can be solved by following some methods or replacing some parts.
Which GM Vehicles have Duramax LMM Engine?
GM introduced Duramax LMM in 2007.
Duramax LMM continued from 2007 to 2011.
The Duramax LMM engine is used in the following GM vehicles:
- GMC Sierra HD
- GMC Topkick
- GMC Savana
- Chevrolet Silverado HD
- Chevrolet Express
- Chevrolet Kodiak
09 Most Common LMM Duramax Problems and Solutions
Although the Duramax LMM engine was way ahead of its time, there are 10 common problems with it, including low fuel rail pressure, winter starting issues, DPF problems, water pump issues, gasket failure, piston failure, etc.
Let’s discuss these problems and possible solutions.
01. Low Fuel Rail Pressure
Fuel filter problems cause low fuel rail pressure.
After 8,000-10,000 miles, the fuel filter became dirty.
So, low fuel rail pressure can happen because of this dirty fuel filter.
A weak FRV (Fuel Rail Valve) is also responsible for low fuel rail pressure.
Solution
The fuel filter is a changeable part.
For better service, replace the fuel filter every 20,000 miles.
The FRV is also replaceable.
You can also change the fuel rail valve to get rid of this issue.
02. Starting Issue in the Winter
Cold weather can affect the Duramax LMM engine as it is a diesel engine.
Spark plugs are normally used to start gas engines.
Diesel engines, however, use glow plugs to ignite the fuel.
Glow plugs become weak after two or three years.
A weak glow plug prevents your car from running during cold weather.
In the winter, this starting issue may also be caused by the fuel filter.
During the winter season, it causes a lack of fuel due to the fact that it collects all trash.
Solution
For better service, replace all glow plugs every 100,000 miles.
You can solve this issue by replacing it.
Change the fuel filter before winter.
The engine will give you better service with a new fuel filter.
03. DPF Issue
Maximum LMM Duramax has a common DPF issue.
It causes the engine to overheat, and so on.
This DPF problem can cause poor engine performance, low fuel economy, and harmful black smoke.
Trash, debris, etc., block this filter, and don’t let it work properly.
Solution
Almost all car manufacturers offer the option of cleaning the DPF.
If there are other issues with your faulty DPF, you need to change it.
It is costly to replace a DPF.
04. Piston Failure
LMM Duramax pistons can be burnt or damaged for various reasons.
If you continuously use low-quality fuel in your engine, it will cause piston failure.
Besides, extreme loads can also lead to a cracked filter.
Acceleration problems, white or gray smoke, and poor performance will notify you of a cracked piston.
Solution
Bad pistons need to be replaced to fix this issue.
The best thing is to go to a car mechanic and buy a new piston to replace the bad ones.
05. Water Pump Trouble
If there is a water pump problem, oil and coolant will start to leak.
And these leaks cause the engine to overheat.
The water pump problem starts after around 100,000 miles.
You must check your water pump when your engine temperature is high and the coolant level is low.
It is not a big issue to worry about.
Solution
Replace the water pump for better performance.
06. Fuel Injector Issue
Fuel injector problem is another common problem of LMM Duramax.
Fuel injectors supply fuel to the truck’s engine.
Some internal issues can corrupt the fuel injector.
Also, the fuel injector can be blocked by debris and trash that cause the engine not to work properly.
Solution
The fuel injector is replaceable and relatively inexpensive to replace.
The engine sign on the dashboard will notify you if there is any problem with the fuel injector or injector tube.
To fix the problem, consult an engine expert and have the injector replaced.
07. Gasket Failure
Another common problem with LMM Duramax is a blown gasket.
It is very risky for your truck to be driven with a blown gasket.
Overheating causes a gasket to blow out.
A blown gasket is responsible for excess loss of coolant.
You can identify a gasket problem by looking at the temperature gauge.
The temperature will drop suddenly if there is a blown head gasket.
Losing excess coolant will also notify you about a blown gasket.
Solution
There is no other solution to this problem except changing the gasket.
It needs to be changed as soon as possible to resolve the issue.
Otherwise, a blown gasket will harm your truck.
08. Transmission Problems
Having a 2007 to 2011 LMM Duramax engine, you may have already faced an Allison 1000 Transmission problem.
The transmission may be faulty if it overheats or has other problems.
Limp mode is also the result of a transmission problem.
Solution
Contact the manufacturer to repair the problem.
Repair or replacement of parts is the only solution to this problem.
09. Overheating
LMM Duramax has an overheating issue.
A faulty radiator can cause the engine to overheat.
Also, running out of coolant causes the engine to overheat.
If your DPF system becomes bad, your engine will overheat.
Solution
Replace the DPF system if it is faulty.
A faulty DPF can damage your car.
If there is a radiator problem, change it immediately to fix the overheating issue.
Is the LMM Duramax Reliable?
Yes, the LMM Duramax is undoubtedly reliable.
It is very similar to LBZ, and it gives excellent performance.
If you are looking for extremely good service, then LMM Duramax can be a good option.
Though it has some common issues, it works much better than its competitors.
It supplies better torque, more horsepower, and higher fuel economy.
Duramax LMM, made between 2007 and 2011, will give you the best service for around 400,000 to 500,000 miles.
So, you can install it in your car without any doubt.
FAQs
What year LMM Duramax is best?
Though all engines are similar, some are more popular.
Duramax LMM engines made between 2007 and 2011 are the best.
How many miles is a Duramax LMM good for?
Duramax LMM is good for over 350,000 miles.
It usually lasts longer than that.
But there have been some problems after a certain mileage.
What are the common problems with a 2008 Duramax?
The most common problems with 2008 Duramax are:
- Transmission problem
- Overheating problem
- Crankshaft failure
- Water pump trouble
- Limp mode issue
Is the 6.6 LMM a good engine?
Yes, the 6.6 LMM is an excellent engine.
It provides excellent service after the installation.
Average mileage is also better than its competitors.
So, it is a reliable engine.
Final Thoughts
Now you know all the common problems with the Duramax LMM engine.
It’s up to you whether you choose to buy it or not.
But as per my suggestion, although the Duramax LMM has some common problems, they are fixable and not costly to fix.
So, you can go for it.
Want to explore other Duramax engine problems? Check out the following articles:
