February 24, 2022

5 Signs of Head Gasket Failure (and what to do about it)


A leaky head gasket can be a, “Oh no! What now?” moment for a diesel truck owner. A cloud of smoke or a surge in the temperature gauge is never a good sign. And it’s not an easy fix.

The head gasket is the seal between the cylinder head and the engine block. It contains the explosive gases from the combustion chamber while allowing coolant and oil to circulate through the engine. It keeps the liquids where they belong, outside of the cylinders.

If the head gasket fails, the oil and coolant can be contaminated with each other, and the combustion gases can escape.

Gaskets are highly engineered precision-manufactured components that are critical to your engine’s operation. They are made of multiple layers of steel and other materials or copper in high-performance applications.

Given that a turbo-diesel can generate up to 75 PSI or more, head gaskets have a tough job. When a gasket starts to show signs of failure, you should pay attention. It’s not a good idea to keep driving if at all possible. The damage from a head gasket leak ranges from pulling the head and reinstalling a new one to a top-end rebuild or even a complete replacement.

Read About: TrackTech Products 101: Fasteners, Gaskets, and More

Keep in mind it’s not always the actual gasket that fails. Often, the fasteners, the engine deck, or the installation process leads to failure.

We’ll look at the top five signs of head gasket failure and one of the best ways to address the problem.

1. Head Gasket Failure Sign: Overheating Engine

An overheating engine is one of the most common signs of a blown head gasket. When the gasket fails, gases leak into the coolant, or the coolant can leak into the cylinders. That means there’s not enough coolant to cool the engine, and the temperature gauge spike in a few minutes. If it gets hot enough, the engine could seize.

2. Head Gasket Failure Sign: Gray, Blue, or Sweet-Smelling Smoke

When the head gasket leaks, coolant and oil flow into places where they’re not supposed to be. White, sweet-smelling smoke pouring out of the exhaust is a sign that coolant is leaking into the cylinders. If the exhaust is gray or blue, oil is leaking into the cylinders. A coolant leak can also produce a strange odor wafting out of the air vents in the cabin.

3. Head Gasket Failure Sign: Loss of Power/Starting

You may experience trouble starting your truck, or it may suffer a noticeable loss of power. Both signs are due to the same root cause. When the gasket isn’t sealing, the engine loses compression because air and fuel are escaping. The engine may turn over but not ignite. Or, it may start but run rough. At this stage, it may be a minor leak and could be safe to drive to a safe or convenient place to park rather than the side of the road.

4. Head Gasket Failure Sign: Coolant Leaks

The coolant may leak from under the radiator cap or leak out around the gasket. New signs of droplets or puddles of coolant are clear indications of a problem. Even if you don’t spot any leaks, you have a leak somewhere if your radiator runs low frequently. If oil leaks into the coolant, the coolant reservoir under the hood could turn black. The LB7 Duramax has been known to blow coolant out of the reservoir while towing if there’s a minor head gasket leak according to Diesel World magazine.

5. Head Gasket Failure Sign: Contaminated Oil

A chocolate milkshake sounds like a good thing, but not in this case. The oil may get contaminated with coolant, so it looks like a milky sludge. You won’t want to drink this one with a straw. You may notice it when you check the oil or change the oil.

Diesel Truck Head Gasket Problems

Head gasket issues have been an issue for diesel trucks since the early days. As we said above, it’s not always technically the gasket’s fault. For any number of reasons, the seal between the engine block and the head is not performing as it should.

If you’re upgrading the power in your truck, upgrade to a performance head gasket rated for the cylinder pressure you have in mind. Otherwise, the cylinder head can lift and stretch the bolts. That leads to a loss of clamping force on the gasket. This can lead to the problems we discussed above, like loss of power, coolant leaks and weird smells and exhaust.

In these situations, the gasket itself didn’t fail. The gasket interface was the problem. So, the unsophisticated engine builder will blame the head gasket for failing. But it’s a poor workman that blames his tools.

Head gasket thickness is an often-overlooked factor to avoid leaks and failures. If you have the engine block decked or resurfaced to achieve a flat, smooth surface, you may need a thicker gasket to maintain the proper piston clearance. Using the wrong head gasket thickness could cause piston-to-valve contact, resulting in serious engine failure. You can have the engine decked multiple times and use slightly thicker gaskets for each round.

One of the most critical factors in head gasket performance is proper clamping force. This is governed by the type of head fasteners, the engine deck fastener holes and structure, and the installation. It’s critical to torque the diesel engine cylinder head fasteners to the correct torque and in the correct pattern as specified in the shop manual or other manufacturers’ instructions.

For example, the Ford 6.0L Power Stroke was notorious for head gasket failures. Many stock engines failed between 70,000 and 150,000 miles. Performance tuners got only 20,000 to 80,000 miles, according to Fleet Service Northwest.

The failure is commonly called a blown head gasket, but that’s not fair. The real problem was that the cylinder head bolts stretched, reducing the clamping force on the gasket. Yes, the gasket leaked, but it wouldn’t have with proper clamping force. The best fix is to install cylinder head studs while replacing the gasket and repairing any other damage to the engine.

According to Engine Builder magazine, the head fasteners in the 2005-2006 6.0L Power Stroke were the common torque-to-yield (TTY) bolts. The goal in using these bolts is to ensure the maximum clamping force. TTY bolts are torqued to a specified setting and then turned an additional quarter or half turn to reach the specified angle of the bolt head. The bolt threads were designed to clamp down a given amount in the final turn to ensure consistent pressure across the head. But things didn’t work out that way. Unfortunately, the bolts were not strong enough to go over 150,000 miles without stretching.

The blighted 6.0L also suffered from EGR Cooler failures. If the internal brazing cracked, pieces could get sucked into the intake manifold and blow the head gasket.

Each engine manufacturer has particular issues leading to diesel head gasket failure. Ram Cummins and GMC Duramax diesels typically have six head bolts around each cylinder, which helps reduce gasket problems. The Duramax V8 engines were designed with 18 head bolts per cylinder bank. The Cummins inline sixes use 24 head bolts. Having more cylinder bolts helps spread the clamping force across the head and around each cylinder. In Ford’s case, the 6.0L and 6.4L Power Stroke engines had four head bolts per cylinder, which contributed to their problems. Hopefully, Ford learned its lesson with six bolts per cylinder on the 6.7L and 7.3L Power Stroke engines.

What Can You Do About Head Gasket Problems?

Whether your truck is packing a Cummins, Duramax, or Power Stroke under the hood, there’s one common remedy to reduce cylinder head gasket problems. Each OEM engine has its quirks and strengths, and some fixes are well documented. But those hard-won tricks of the trade may not apply to the other engines.

Here’s the one universal upgrade you can make: install high-performance head studs. Precision manufactured to very high tolerances, head studs can handle the increased pressure of turbo diesel pulling at the upper end of its weight limit, climbing the Rockies on a hot summer day.

Read About: Why Gasket Thickness Matters

Plus, head studs make it easy to remove and replace the head using the same fasteners. If you’re constantly tweaking your engine, that could save a lot of time and money. Plus, it’s easier to maintain a consistent clamping force across the block to keep the head gasket where it needs to be.

TrackTech Fasteners understands that fasteners are perhaps the most critical component of any engine. No matter how well other parts perform, a weak fastener can be catastrophic for the performance – and even the life – of your vehicle. That’s why we’ve developed a wide range of heavy-duty fasteners, including the strongest head studs in class for a wide range of diesel trucks, including the Ford Power Stroke, Chevy Duramax Silverado, Dodge Cummins Laramie, and many others.

TrackTech Fasteners are tested under the harshest conditions both in a lab and on the track, so buyers know they are getting the best possible quality. If you’re worried about head gasket failure on your diesel pickup truck, turn to TrackTech Fasteners® for peace of mind.

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