3 Common Duramax Diesel Engine Problems and How To Fix Them

Written By JD Diagnostics & Diesel Repair on Nov 15, 2021

If you need a vehicle with lots of power and versatility, then opting for a truck with a diesel engine is imperative. In the past year, there has been a 28% increase in the number of diesel vehicles sold in the United States. One of the most popular diesel vehicle manufacturers on the planet is General Motors. 

The 6.6-liter Duramax diesel engine is one of the main motors you will find in General Motors (GM) trucks. While these engines are extremely durable and reliable, they do have some problems. Here are some common Duramax diesel engine problems and what can be done to fix them. 

Most Common 6.6-liter Duramax Problems

1. Issues With the Fuel Lift Pump

Duramax diesel engines use a direct injection fuel system. One of the most important parts of this fuel system is the fuel injection pump. The CP3 fuel injection pump that comes stock in most Duramax engines are reliable, but they are not very powerful. 

Since there is no lift pump for this fuel system, the injection pump has to work very hard to both suction fuel from the tank and pressurize the fuel. The lack of a fuel lift pump usually results in a loss of fuel rail pressure when the engine accelerates. 

How To Fix This Lift Pump Problem

Probably the best way to fix this common Duramax problem is by adding an aftermarket lift pump. With the addition of a lift pump, you can make your Duramax engine last longer. A new lift pump also improves engine performance and reduces emissions. 

2. Water Pump Problems Are Common

Newer Duramax engines come equipped with water pumps that have plastic impellers. These impellers are extremely weak and prone to failure. Water pumps on Duramax engines are also prone to leaking. These leaks can result in engine overheating issues. Water pump leaks also affect system pressure, which can result in coolant supply inadequacies. 

Replacing a Duramax Water Pump

When confronted with a damaged water pump, you need to replace it right away. Finding a water pump replacement with an iron impeller is a good idea. Replacements with these impellers tend to last longer and perform better. If your Duramax engine has lots of miles, you may want to consider changing your thermostat and water pump housing. Doing this can help you avoid further issues with your cooling system in the future. 

3. Duramax Engines Are Notorious For Fuel Injector Problems

Perhaps the most common complaint you will hear from Duramax diesel owners is in relation to the original fuel injectors these engines come with. The team at GM even admitted their injectors were poorly designed and fixed them in the past few years. One of the main problems with these injectors is that they are prone to cracking. 

These injectors also have fault ball seats. The faulty ball seats make these injectors leak over time. Bad injectors can create problems with loss of power, rough idling and excessive smoke. 

Remedying Your Injector Issues

Replacing faulty injectors is really the only way to address this problem. These injectors are located under various other engine components, which is why hiring professionals to replace them is a wise move. 

Don’t Let Your Duramax Engine Problems Linger

If you are currently dealing with the Duramax engine issues mentioned in this article, you need to take action. The longer you let these issues linger, the more damage they will cause. With the help of a knowledgeable diesel mechanic, you can get your Duramax diesel engine issues diagnosed and fixed in a hurry. 

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