What Is A Head Gasket? Guide To Your Detroit Diesel or Cummins Engine’s Workhorse

October 5, 2021

Your head gasket is a critical component of your vehicle’s Detroit Diesel or Cummins engine. But, what is a head gasket? This flat sheet of metal is found sandwiched between your engine block and cylinder head and is considered to be your engine’s workhorse. What is the purpose of a head gasket? Well, in addition to sealing the engine block and cylinder heads of your engine so oil and coolant can properly circulate, the head gasket also seals the combustion chamber within your engine. With the proper sealing of these three main components, your vehicle will be able to produce enough power to move. It also will aid in keeping harmful gases from exiting your combustion chamber by directing them through to the exhaust system.

In addition to sealing the combustion chamber, engine block and cylinder head, the head gasket has several other duties. Within the combustible engine, the head gasket ensures the pressure created from the spark plug’s ignition of fuel vapors can’t escape from the combustion chamber. The combustion chamber contains pistons that require high pressure to ensure they continue to fire appropriately. In addition, the head gasket keeps your oil and coolant chambers separated to ensure no cross-contamination occurs.

In addition to sealing the combustion chamber, engine block and cylinder head, the head gasket has several other duties. Within the combustible engine, the head gasket ensures the pressure created from the spark plug’s ignition of fuel vapors can’t escape from the combustion chamber. The combustion chamber contains pistons that require high pressure to ensure they continue to fire appropriately. In addition, the head gasket keeps your oil and coolant chambers separated to ensure no cross-contamination occurs.

Throughout this article, we’ll highlight some more facts that help shed some light on the question, “What is a head gasket?” We’ll help you understand the types of head gaskets available, some signs of a blown head gasket and how you can go about replacing a head gasket in your Detroit Diesel or Cummins engine.

What Are Head Gaskets Made Of?

Now that you know what head gaskets do, let’s talk about what head gaskets are made of. In the past, head gaskets were constructed from either graphite or asbestos. In modern times, head gasket materials have evolved to eliminate the health risks associated with these past models and provide better sealing capabilities for your motor. While all head gaskets have the same duties, not all are the same. There are four main types of head gaskets that can be used in a Detroit Diesel or Cummins engine, each constructed from different materials in different ways.

Multi-Layer Steel

The most common types of head gaskets available for modern Detroit Diesel or Cummins are made from multi-layered steel. These head gaskets, as their name implies, feature multiple layers of steel that can range anywhere from two to five layers. The various layers are joined together using either an elastomer or adhesive and are treated with a gasket coating for maximum durability. Multi-layer steel head gasket materials are popular because they have been proven to withstand more significant pressure than other types of head gaskets.

Copper

Some vehicles use head gasket materials made from solid copper, which allows for superior strength and protection against leaks. Due to their copper construction, these types of head gaskets require some extra work to install. Those who choose to install them in their Detroit Diesel or Cummins engines must use a particular machine called an o-ring machine, making them a labor-intensive and costly option.

Composite

While not commonly used today, many vehicles from the 1980s feature composite head gasket materials. Composite typically refers to graphite – a weaker option when compared to multi-layer steel or copper. Graphite can protect against leaks, but it doesn’t really compare to newer head gasket materials. Most manufacturers have phased out composite head gaskets in favor of more contemporary materials.

Elastomeric

The final head gasket material available is elastomeric. These types of head gaskets use a strong steel core coated in rubber elastomeric beads. The elastomeric beads help to create a strong seal for the coolant and oil passages to protect the engine from leaks.

What is A Blown Head Gasket?

Detroit Diesel or Cummins head gaskets can blow when the seal between the cylinder head and engine block busts. Your head gasket sits between these two areas of the engine to perform its duties – when it fails, your coolant and oil can both leak, and gas can escape from the combustion chamber.

There are many reasons for head gasket failure within your Detroit Diesel or Cummins engine, but the most common cause tends to be overheating. In these models, high engine temperatures themselves are typically caused by a lack of coolant within the radiator, which can also occur from a leak. Some head gaskets can weaken sooner depending on the materials used, such as composite vs. multi-layered steel. Once the head gasket has blown, you must address it immediately. If you continue to operate your vehicle as normal with a broken head gasket, you can cause severe and sometimes irreparable damage to the motor. After a gasket blows, it can no longer act as a seal to maintain the pressure that is key for engine power.

Luckily, there are some signs of a blown head gasket you can look for to ensure you can go about replacing it as soon as possible. Some of the signs of a blown head gasket to watch for include:

  • Thick, white smoke coming from your exhaust.
  • Poor engine performance & a rough noise during idle.
  • Milky-colored engine oil due to the mixing of fluids.
  • An overheating engine or bubbles in the radiator.
  • Oil and coolant leaks on the exterior of the vehicle.

These symptoms may appear minor at first, and you may be tempted to ignore them. We highly recommend you get your vehicle checked out immediately if you notice one or all of them. Minor problems can quickly become big ones, and they may be signs you need to start thinking about replacing your head gasket.

Replacing a Head Gasket

Head gasket replacement in your Detroit Diesel or Cummins engine is considered to be one of the most challenging jobs for enthusiasts and mechanics alike. Most people probably want to know how to fix a blown head gasket without replacing it. Unfortunately, for these models of engines, this is only possible if you’ve caught the signs of a blown head gasket very early on. If you have, you can apply a quality sealer to stop leaks. If the head gasket is too far gone, you’re more than likely going to need to start thinking about replacing it. Finding the proper parts for head gasket repair is simple, just select your engine model and you’ll be able to find the right gasket for your head.

While head gasket parts aren’t too expensive, the labor it takes a mechanic to do the job can end up costing thousands. However, it is entirely possible to perform gasket repair yourself – just be sure to always consult your vehicle’s service manual if you’re thinking about taking the job.

We’ve compiled a list of six general tips you can use when replacing the head gasket of your Cummins or Detroit Diesel engine on your own.

  1. Always mark and index everything on your engine before starting removal.
  2. Check the cylinder head and block for flatness. You can check your service manual for the exact specifications; if they’re out of line, you’ll have to send them to a machine shop to be repaired.
  3. Do not use tools that will remove or scratch the metal on the engine block’s deck or mounting surface of the cylinder head. Surface irregularities can cause more issues in the future.
  4. Clean your bolt or stud holes before putting head bolts back in. Any interference within the threads can throw off your torque readings.
  5. Never use sealant unless the manufacturer specifically requires you to. Head gaskets that require sealants will come with the proper type, and the service manual will outline where and how much you should put on.
  6. 6. Always tighten head bolts in the proper sequence and torque as outlined by the service manual. If you don’t, your head gasket will not be installed appropriately and can fail quickly.

How to Prevent Head Gasket Failures

The best way to prevent head gasket failure for a Cummins or Detroit Diesel engine is to ensure your cooling system is working correctly and keep your engine properly tuned. Sticking to Cummins or Detroit Diesel’s recommended service schedule is the best way to keep your head gasket in a healthy condition. When you flush your coolant or antifreeze, always replace it with high-quality products that offer good protection for your engine.



If You’re Thinking About Replacing Your Head Gasket for Your Cummin or Detroit Diesel Engine, Shop Diesel Pro Power

Now that you know the answer to the question, “What is a head gasket?” you’ll be able to tell if yours is in healthy shape, or if you need to think about replacing it. If you’re seeing signs of a broken head gasket in your engine, check out our online shop full of top-rated head gasket replacement parts for makes and models of all kinds. We carry high-quality parts for regular and diesel engines such as Detroit Diesel, Cummins, Twin Disc and Allison. If you need assistance with purchasing a replacement head gasket, feel free to contact the experts at Diesel Pro today. Or, you can give us a call at 888-433-4735 in the U.S. and 305-545-5588 internationally.

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