Diesel Engine Wastegates Explained: How It Works, Calibration, And Engine Problems

Here at Highway & Heavy Parts, we have gone into extensive details on how turbochargers work. Besides the diesel engine itself, the turbo is the next most important component in making sure your truck operates properly.

If you want to get up to speed on turbochargers, how they work, and what causes them to fail, we suggest reading How Diesel Engine Turbochargers Work. Once you're up to speed with that, it's time to learn about wastegates.

Diesel Engine Turbocharger Wastegate

Chances are, that if you have been around forced induction internal combustion engines (even gas ones), you have heard the term wastegate mentioned before. But do you know what it does and how it works? We are here to help clear up some of that mystery.

The next time someone starts talking about wastegates and how they help the diesel engine work, you won’t just smile and nod politely without actually knowing what they are talking about. 

We are going to answer some of the most common questions related to boost pressure, turbochargers, and wastegates on diesel engines.

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How Does A Turbocharger Work?

Your engine, regardless if it’s gasoline or diesel-powered, is, at its core, an air pump. The more air it can get in, the more power it makes. If you can force additional oxygen in the combustion system, you get more power. It’s that simple.

Diesel Engine VGT Turbocharger

This is where forced induction comes in. There are a few different ways to get additional air to enter the combustion chamber on your diesel engine. Most commonly, it is done via a turbocharger. 

They make use of the spent gas coming from the engine by putting a turbine on the exhaust manifold. A secondary compressor wheel is added to help suck in the fresh air which is then fed into the intake. This is done via a shaft that is put between the hot and cold side of the turbo. 

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How Does A Diesel Wastegate Operate?

All right, enough about turbochargers. You’ve come here to learn how a diesel wastegate operates, right? In simple terms, the wastegate on a diesel engine creates a “leak” in the exhaust side of the turbocharger when the pressure gets to be too much. 

The intake side has an actuator that measures the amount of air going in. As the pressure or boost increases, the actuator will begin to open the wastegate on the exhaust side. Each turbocharger will have specific limits that will tell the wastegate when to open and close based on the manufacturer.

A wastegate is simply designed to be a failsafe unit so that the increased boost won’t end up exploding the housing from too much pressure. By allowing the spent gas to bypass the turbine and go straight out the exhaust pipe, the wastegate has done its job properly. 

Wastegate Calibration

Turbo Diesel wastegates pressures are calibrated specifically for each make and model. Most manufacturers calibrate their wastegates to be on the safer side, meaning that they will stay within specified pressures to ensure long service life. 

Unfortunately, by doing this, horsepower and torque are often sacrificed. You may have heard or even seen some owners physically clamping or kinking the wastegate hose. In theory, this will get you more boost pressure, which gives you more power. But, and this is a bit BUT, you might run the risk of having the turbocharger physically explode. 

Diesel engine turbochargers spin anywhere between 80,000 RPM and 200,000 RPM. The centrifugal force applied to its components is incredible, and by not allowing the wastegate to do its job, you could run the risk of severe problems.

 

7 Common Turbo Diesel Engine Problems

The internal combustion engine is a complicated piece of modern engineering. It is the result of thousands of moving and non-moving parts all working together in perfect harmony. The smallest problem such as a defective wastegate could mean thousands of dollars in repair bills and countless hours of downtime. 

Keeping your truck in tip-top condition is the key to getting the most out of it. From periodic maintenances such as changing the oil on time to daily visual inspections, keeping everything in good working condition is extremely important! 

Below, we have compiled a list of other 7 issues that can negatively affect your turbocharger and wastegate:

1. Pugged air cleaner

Changing your air filter on time can have several positive benefits. Better throttle response, longer turbo service life, and increased horsepower are just some of the advantages of changing your air cleaner regularly.

2. Excessive Crankcase Pressure

The easiest way to prevent excessive crankcase pressure on your turbo diesel engine is to make sure the oil is not overfilled. Too much oil in the crankcase could cause excessive crankcase pressure.

3. Drain Line Restriction 

In general, drain lines are a certain size so that they can accommodate the proper amount of fluid coming out. A plugged or restricted drain line can affect the overall performance of a turbocharger and/or wastegate. 

4. Valve Guide Seals or Piston Ring Failure

If your valve guide seals or piston rings fail, you might notice a big drop in performance and additional smoke coming from your exhaust. Additionally, this can affect the overall functionality of the turbocharge and wastegate. 

5. Damaged Compressor Wheel

Turbochargers work with watch-like accuracy. Sometimes, even the smallest particle getting into the system can end up causing serious damage. Keeping your air filter clean and making sure it’s on securely will often be the best way to prevent compressor wheel damage.

6. Damaged Turbine Wheel 

Heat, excessive PRM’s and foreign matter can all affect the turbine wheel. Periodic inspection of your turbocharger is a good way to spot potential turbine wheel defects before they become a bigger issue.

7. Turbo Bearing Faliure

As previously mentioned, diesel turbo engines can spin upwards of 200,000 RPM. The bearings on the shaft that connect the compressor and turbine wheel will take a beating. If not caught in time, they can fail, taking the entire turbo down with it. 

Keep in mind that the issues noted above are just some of the causes of diesel turbocharger failures. Oftentimes, it is not just a single symptom, but a combination of many problems that lead to turbo malfunction. 

The wastegate system is made to help keep your turbocharger healthy give you millions of trouble-free miles. If keeping your turbocharger in optimal running condition is important to you, read about other Ways to Keep Your Turbocharger Healthy!

 

Final Words 

Regular maintenance and inspection of the entire engine system are one of the best things that can be done to help prevent issues. If caught early enough, it can help save money and downtime. 

Got additional questions about your wastegate system? Give us a call today at 1-844-304-7688 or request a quote online today! Our ASE-certified staff is standing by and ready to help clear up any concerns you may have about your diesel truck.

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