06 Common LBZ Duramax Problems and Solutions

GM began producing the Duramax LBZ engine in 2006 and continued from 2006 to 2007.

LBZ is a highly capable and reliable engine.

In Duramax’s engine lineup, it is regarded as the best.

Though it is known as one of the most reliable engines, it also has some common issues.

Most of these problems are minor and solvable.

Vehicle Application of the Duramax LBZ Engine

The Duramax LBZ engine is used in:

  • GMC Sierra HD
  • GMC TopKick
  • Chevrolet Silverado HD
  • Chevrolet Kodiak

The Most Common LBZ Duramax Problems

LBZ Duramax has 8 common problems, including head gasket failure, water pump failure, glow plug failure, cracked pistons, EGR valve failure, and transmission line leaks.

 1. Head Gasket Failure

Duramax LBZ Head Gasket Failure

One of the most common problems with Duramax LBZ is gasket failure.

Head gasket failure is a major problem that should be fixed quickly.

When the gasket fails, coolant leaks will be visible.

Coolant leakage is a sign of gasket failure.

Your vehicle will overheat if there is a blown gasket.

Your car’s temperature gauge can provide information about a failed gasket.

Your truck’s temperature gauge provides information about a failed gasket.

The sudden drop in temperature will alert you that you have a blown gasket.

Besides, you can know about it by noticing the excess loss of coolant.

Additionally, you can detect it by observing an excessive coolant leak.


And it is not possible to repair a failed gasket.

You should replace the broken gasket as soon as possible to fix the problem.

 2. Water Pump Failure

Duramax LBZ Water Pump Failure

Water pump failure is a common issue with almost all Duramax engines.

After driving for a long time, over almost 100,000 miles, the water pump will trouble you.

Your vehicle’s coolant or oil will start leaking if there is a problem with the water pump.

A failed water pump can cause a severe coolant leak in your vehicle.

At the same time, the temperature of your vehicle will start rising suddenly.

Therefore, low coolant levels and high temperatures are signs of a failing water pump.


It is very common to have a problem with the LBZ water pump.

Change the water pump, and your truck will perform better.

3. Glow Plug Failure

Duramax LBZ Glow Plug Failure

The stock glow plug’s quality in the Duramax engine is not up to the mark.

If your glow plug is faulty, it will be difficult for the engine to start because the engine starts with the help of the glow plug.

It produces the required heat for starting the engine.

So, starting your engine is only possible if the glow plug is good.

If the glow plug fails, your vehicle will emit excessive black or white smoke.

Check whether the glow plug is good or not if your vehicle produces smoke.

You need to change the glow plugs every 20,000 miles.

Don’t be worried, as it is not a major problem.


Changing the glow plug is the only solution to this problem.

 4. Cracked Piston

Low-quality piston sets are another common issue with the Duramax LBZ engine.

The piston gets cracked within the first 100,000 miles.

Driving your car with a cracked piston is dangerous.

Pistons can be burned or cracked for several reasons.

For instance, towing a heavier load than the towing capacity causes the piston to break down.

Besides, using low-quality fuel and coolant is also harmful to the pistons.

It causes a piston to blow out.

Use high-quality fuel to keep your pistons safe.

If there is too much smoke from the exhaust or the truck’s power output is reduced, it is a sign that your piston may have been cracked.


Changing the cracked piston is the only solution to this problem.

Changing the piston in the Duramax LBZ engine will cost around $1100.

 5. EGR Valve Failure

Duramax LBZ EGR Valve Failure

EGR valve failure is another common issue with Duramax LBZ.

It tends to fail within 150,000 miles.

The EGR valve can be clogged with debris or other trash.

You will smell gasoline if there is any problem with this EGR valve.

Your vehicle will burn more fuel if there is any problem with the EGR valve.


Take your vehicle to an experienced mechanic to find out why the EGR valve broke and how to fix it.

 6. Transmission Line Leaks

Duramax LBZ Transmission Line Leaks

Transmission failure is another common issue with the Duramax LBZ.

It is not a minor issue to avoid.

Damaged cooling lines, hardened seals, and deteriorated gaskets can cause transmission line leaks.

There are several moving parts in the transmission.

It will start leaking if any part of the transmission gets damaged or broken.

The fluid leaks under the truck will notify you about transmission line leaks.


Replace the transmission lines instead of patching them.

A transmission line is not costly.

It costs around $50 to $200.

Final Thoughts

Two of these issues are major, while the remaining four are minor.

If you plan to buy a truck with a Duramax LBZ engine, don’t hesitate, you can go for it.

The performance of Duramax LBZ won’t disappoint you.

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