lbz duramax problems

LBZ Duramax Common Problems (Explained)

In this post, we are going to be looking at LBZ Duramax’s common problems. The Duramax engine was designed by General Motors (GM). The engines are manufactured by DMAX, a joint venture of the Isuzu and GMC companies. It is generally considered to be one of the best ever Duramax engines.

Though it has a great track record, it does also come with some significant problems associated with it. When compared with other engines in the Duramax line, significant improvements

What Problems Does LBZ Duramax Have?

The LBZ has its drawbacks. The turbocharger can be removed often due to vane stick problems. The pistons of the engine are made of aluminum which makes them prone to cracking at 600rwhp.

The LBZ has water pump problems which give out when the car reaches 100 000 miles. This results in the overheating of the engine.

Furthermore, the lack of a lift pump is a common problem amongst the Duramax engines which was only rectified later on in the 2017 model. Another common problem is the transmission cooler lines leaking. It’s quite commonly reported but the good thing is that it’s an easy fix and an inexpensive one at that.

If you are looking to buy a used LBZ Duramax engine, you should expect to pay five figures for it. The main reason for this is due to the fact that it is quite a popular engine especially for racing enthusiasts. It’s relatively easy to tune and is often turned into a hot rod.

However, if pushed to around the 700HP mark, it will rack some pistons. If this is something that you are looking into, you should be mindful of this fact and not push the engine close to these levels.

The next problem I will talk about is not something that you will experience in stock. However, when you tune it, the Allison transmission that comes with these engines will put the truck into limp mode if it detects the slightest amount of slippage. It’s a fine line you would have to walk should you choose to tune your engine.

Is the 6.6 LBZ Duramax Reliable?

LBZ model has enhanced power. It was a worthy competitor of the 5.9 litre Cummins engine which produced 325 horsepower and 610 lb-ft and power stroke engines’ 325 horsepower and 570 lb-ft. The LBZ can withstand significant modifications, hence is quite popular with enthusiasts.

The LBZ can easily be regarded as the most durable engine of the Duramax. The engine has significant factory power. The engine block is strengthened with more webbing, stronger main bearing caps, and 4mm deeper bores. Rods were changed to forged steel.

The rods and block are extremely capable and are an improvement from the LLT and LB7 whose rods were susceptible to bending.

How Many Miles Will a Duramax Last?

The Duramax engine is reliable and durable. When properly taken care of the, engine lasts about 300 000 miles. At 200 000 miles, the engine requires changes to water pumps and other essential parts of the engine.  Owners have reported that their trucks have given them as many as 500 000 miles of service

What is High Mileage for an LBZ Duramax?

The high mileage for the LBZ is considered at 300 000miles. The LBZ engine is versatile, reliable, and durable. If the engine is regularly serviced and maintained, it can reach a mileage of close to 500 000 miles.

Is LBZ the Best Duramax?

The LBZ engine is the best among its peers during the 05- 06 period. The LBZ is also the best Duramax engine to be made. The systems introduced by the LBZ were adopted in later versions.

The high factory performance coupled with an extensive capacity for tuning makes it the ideal car for heavy-duty use and for car enthusiasts who prefer higher horsepower motor vehicles.

The issues with the engine are relatively few compared to the other models of the Duramax. The Allison 1000 automatic transmission system provides efficiency and maximum output from the LBZ engine.


The LBZ is Duramax’s best edition. The engine has power and is drivable, reliable, and tunable. It is perfect for heavy-duty use and for car enthusiasts. This makes the LBZ a versatile and practical engine suitable for all occasions.

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