Cummins 6.7L Head Gasket Failure Symptoms, Causes, and Repair Options

Overview of the Cummins 6.7L Engine

The Cummins 6.7L turbo diesel engine was introduced in 2007.5 model year Ram 2500 and 3500 trucks. It continues to be offered today and is regarded as one of Cummins' most reliable diesel engines.

The 6.7L features a straight-six cylinder configuration with 24 valves. It displaces 408 cubic inches (6.7 liters) and utilizes a variable geometry turbocharger. The engine is offered with three power levels: 325 hp/610 lb-ft torque, 350 hp/660 lb-ft torque, and 385 hp/850 lb-ft torque.

Common Issues with the 6.7L Cummins

Despite its reputation for reliability, the 6.7L Cummins is not without its common problems. Some of the most reported issues include:

• Failed emissions components like the diesel particulate filter, diesel oxidation catalyst, NOx sensor
• Exhaust gas recirculation (EGR) system problems
• Turbocharger failures
• Fuel system problems like lift pumps and injectors
• Oil leaks from gaskets and seals

One of the most critical gaskets on the 6.7L Cummins is the head gasket. If this gasket fails, it can lead to major engine damage.

Symptoms of a Blown Head Gasket

Some of the most common symptoms of a blown head gasket on the 6.7L Cummins include:

• White smoke from the exhaust
• Overheating without other leaks
• Bubbles in the radiator
• Engine oil contamination
• Coolant loss with no visible leaks
• Rough running or misfire

If you experience any of these symptoms, it's imperative to have the 6.7L Cummins inspected by a diesel mechanic. A blown head gasket can cause thousands of dollars in damages if left unchecked.

Causes of Head Gasket Failure

There are several root causes for a failed head gasket on the 6.7L Cummins:

• Overheating - can warp and damage head/block mating surfaces
• Improper torque on head bolts - leads to inadequate clamping force
• Repeated heat cycles - normal wear over time
• EGR soot - can erode gasket seals over time

No matter the cause, a blown head gasket needs prompt attention to avoid further damages.

6.7L Cummins Head Gasket Repair Options

Once you've diagnosed a bad head gasket on your 6.7L Cummins, you have a few repair options:

Stock Replacement Head Gasket

The most straightforward option is to purchase a new, OEM head gasket and perform the replacement yourself or have a shop do it. Stock gaskets run $200-$300 plus labor costs.

The downside is that the replacement gasket is prone to the same failure points as the original. For severe issues, an aftermarket gasket may be better.

Multilayer Steel (MLS) Head Gasket

For better longevity, many technicians recommend upgrading to a multilayer steel (MLS) style head gasket. Popular options are from companies like Cometic and ARP.

MLS gaskets feature multiple layers of stainless steel. This allows more even clamping force across the head/block surface. MLS gaskets run $500-$600 but are less likely to fail over time.

O-Ring Head Gaskets

An even more robust choice is an O-ring style head gasket for the 6.7L Cummins. These feature Viton O-rings around each cylinder for maximum sealing. Brands like Firepunk Diesel offer O-ring kits.

O-ring gaskets are the preferred solutions for high performance builds making big power. They ensure a leak-free seal around the cylinders. Expect to pay $800-$1000 for a complete O-ring kit.

DIY or Professional Replacement?

Replacing the head gaskets on a 6.7L Cummins is an involved process. It requires removing the cylinder heads, checking for flatness, cleaning gasket surfaces, replacing the gaskets, re-torquing the heads, and refilling fluids.

With specialty tools and experience needed, this is a job best left to professional diesel technicians. They have the skills to properly replace the gaskets without damaging other components.

However, with time and care, it is possible for hobbyists to DIY this repair and save on labor costs. Having a factory service manual is highly recommended before attempting.

Finding a Shop

When looking for a shop to replace your 6.7L Cummins head gaskets, be sure to find one specialized in diesel repairs. Ask around for referrals to the best local diesel mechanic.

Also check shop reviews online and ask about their experience with 6.7L Cummins repairs. Do they offer a warranty on their work? What gasket options do they recommend?

Finding a competent shop will give you peace of mind through the repair and ensure no corners are cut.

Preventing Future Head Gasket Failures

Once your 6.7L Cummins head gaskets have been replaced, you'll want to take precautions to prevent repeat failures. Here are some tips:

• Install an aftermarket coolant filtration kit to remove corrosive particles
• Install an EGR blocker plate kit to reduce soot contamination
• Use a coolant additive to strengthen gasket seals
• Install a coolant bypass kit to reduce heat cycles
• Upgrade to a reinforced head gasket like MLS or O-ring
• Closely monitor EGTs and coolant temps to avoid overheating

Performing routine maintenance and services on your 6.7L Cummins is also critical. Be diligent about oil changes, fuel filter changes, etc to extend the engine's service life.

With attention and care, your rebuilt 6.7L Cummins can deliver years of reliable service once again.

FAQs

What are the most common symptoms of a blown head gasket on the 6.7L Cummins?

White smoke from the exhaust, overheating without other leaks, bubbles in the radiator, engine oil contamination, coolant loss without visible leaks, and rough running/misfires are the most common symptoms of a 6.7L Cummins head gasket failure.

What typically causes a head gasket to fail on the 6.7L engine?

Overheating, improper torque on head bolts, excessive heat cycles, and EGR soot erosion are the most common causes of head gasket failure on the 6.7L Cummins.

What are the options for repairing a failed 6.7L head gasket?

Options include replacing with a stock gasket, upgrading to a multilayer steel (MLS) gasket, or opting for an O-ring style head gasket kit. An experienced diesel shop can advise on the best choice.

Is the 6.7L head gasket replacement a DIY job?

While theoretically possible for a hobbyist, the complexity of the 6.7L Cummins makes this repair best left to professional diesel technicians with proper tools and experience.

How can I prevent repeat head gasket failures on my 6.7L Cummins?

Installing coolant filtration, EGR blockers, coolant additives, bypass kits, and upgraded head gaskets can help. Closely monitoring EGT and coolant temps is also critical.