If you own a 6.7 Cummins engine, you know how important it is to keep it running smoothly.
However, like any other engine, it is susceptible to problems, and one of the most common issues is a blown head gasket.
A blown head gasket can cause a wide range of problems, from loss of power and overheating to coolant leaks and low compression. Keep reading to find more information.
6.7 Cummins Head Gasket Symptoms
Here are the symptoms of head gasket failure in the 6.7 Cummins engine:
Loss of Engine Power and Overheating
A blown head gasket in the 6.7 Cummins engine can cause a loss of engine power, as well as overheating.
Overheating can occur due to the engine’s inability to properly regulate coolant flow and combustion chamber temperatures.
As the engine temperature rises, it may cause a decrease in engine power, leading to a rough idle or stalling.
Oil and Coolant Mixing
Antifreeze can mix with oil due to a blown head gasket, leading to a worse heat exchange reaction.
A visual sign of this is an oil film in the coolant reservoir .
Poor Engine Performance
A blown head gasket can cause a decrease in engine compression, which can lead to poor engine performance.
This may result in engine misfires, rough idling, and a loss of power.
White Smoke from the Exhaust
White smoke from the exhaust can be an indication of a blown head gasket.
This is due to coolant leaking into the combustion chamber and being burned with the fuel.
A blown head gasket can cause coolant to leak from the engine.
This may result in a noticeable loss of coolant and the need to frequently refill the coolant reservoir.
Diagnosing head gasket issues in a 6.7 Cummins engine
Here are some tests that you can perform to diagnose the issue:
Check the Engine Oil
One of the easiest and most effective ways to test for a blown head gasket is to check the engine oil.
If the oil is a milky white color, like coffee with too much cream, it means that the coolant is mixing with the oil, and you do have a blown head gasket on your hands.
It is also recommended to drain the oil from the pan to check for signs of coolant contamination.
Look for External Leaks
Check for leaks to the outside, such as coolant stains on the bottom of the head near the gasket joint.
Inspect the Coolant
Check the coolant for signs of contamination, such as a brownish or milky color, which indicates that the coolant and oil are mixing.
Perform a compression test on each cylinder to check for low compression, which is a sign of a blown head gasket.
Look for Exhaust Gases in the Coolant
Check for exhaust gases in the coolant using a chemical test such as Blockcheck.
Check for Pressure in the Cooling System
If there is pressure building up in the cooling system, this is another telltale sign of a blown head gasket.
Repair options for a failed head gasket in a 6.7 Cummins engine
Here are some of the common repair options for a failed head gasket in a 6.7 Cummins engine:
Thread chaser and reassembly process: Before beginning any repairs, it is important to run a thread chaser into the head bolt holes to ensure a secure fit.
Once everything is clean and dry, the reassembly process can begin.
The new gasket should be carefully placed on the engine, and the head should be lowered onto the engine, ensuring it registers into the alignment dowels.
Fire ring grooves and MLS gasket:
In the event of a head gasket failure, some people opt for a bomb-proof top-end solution.
This involves cutting fire ring grooves in the head, using mild steel fire rings, and utilizing a factory 6.7L MLS gasket with center rings removed.
While there are DIY repair options available, a professional repair may be the best choice for some.
This may involve taking the vehicle to a reputable mechanic who specializes in Cummins engines.
They may have access to specialized tools and equipment and can ensure that the repair is done correctly the first time.
Upgrade cylinder head fastener:
Head gaskets can fail due to overworking. In this case, upgrading the cylinder head to the engine block fastener to a better one may be an ideal solution.
The 6.7 Cummins has a high-pressure common-rail system that sends fuel to the engine, which works faster and better than previous systems.
Preventing head gasket issues in the 6.7 Cummins: maintenance tips and best practices
Here are some tips on how to prevent head gasket issues in the 6.7 Cummins:
Use the right head gasket:
The head gasket used in the 6.7 Cummins is a factory 6.7L MLS unit, but it is recommended to remove the center rings and uses mild steel fire rings instead.
These fire rings should be .105-inches thick and cut between .040-inch to .041-inches deep to accommodate the 4.340-inch inside diameter of each ring.
During installation, it is important to clean and dry the engine, use a thread chaser to clean the head bolt holes, and ensure the head registers into the alignment dowels.
Proper installation will prevent any leaks or damage to the gasket.
Overheating is a common cause of head gasket failure in the 6.7 Cummins.
To prevent overheating, make sure to keep the cooling system in good condition, check for any leaks, and ensure the coolant is at the right level.
Monitor drive pressure:
High cylinder pressure can also contribute to head gasket issues.
It is recommended to monitor the driving pressure and avoid excessive pressure that can lead to gasket failure.
Use high-quality parts:
When replacing parts in the engine, use high-quality parts that are designed to handle the power and performance of the 6.7 Cummins.
This includes head studs, valves, and other critical components.
You should perform regular maintenance to keep the engine in good condition. It can help prevent any issues that can lead to head gasket failure.
This includes oil changes, filter replacements, and inspections of the cooling system and other components.
Frequently Asked Questions
What Are The Common Symptoms Of A Blown Head Gasket In A 6.7 Cummins Engine?
Some of the most common symptoms of a blown head gasket in a 6.7 Cummins engine include loss of power, overheating, white smoke from the exhaust, coolant leaks, oil leaks, and low compression in one or more cylinders.
How Can I Tell If My 6.7 Cummins Engine Has A Blown Head Gasket?
If you notice any of the symptoms mentioned above, it is likely that your 6.7 Cummins engine has a blown head gasket.
However, the best way to confirm this is to perform a compression test and a leak-down test to check for low compression and coolant leaks.
What Causes A Blown Head Gasket In A 6.7 Cummins Engine?
There are several factors that can cause a blown head gasket in a 6.7 Cummins engine, including overheating, excessive pressure in the cooling system, low coolant levels, and poor maintenance.
Can I Still Drive My 6.7 Cummins Engine With A Blown Head Gasket?
While it is technically possible to drive a 6.7 Cummins engine with a blown head gasket, it is not recommended.
Driving with a blown head gasket can cause further damage to the engine and may lead to costly repairs down the road.
How Much Does It Cost To Replace A Head Gasket In A 6.7 Cummins Engine?
The cost of replacing a head gasket in a 6.7 Cummins engine can vary depending on several factors, including the severity of the damage and the cost of parts and labor in your area.
You have to spend $1,500 to $ 3,000 for this service.
How Can I Prevent A Blown Head Gasket In My 6.7 Cummins Engine?
To prevent a blown head gasket in your 6.7 Cummins engine, it is important to maintain proper coolant levels, avoid overheating the engine, perform regular maintenance, and address any symptoms of a blown head gasket as soon as they appear.
A blown head gasket can be a serious problem for your 6.7 Cummins engine.
Regular maintenance, proper coolant levels, and avoiding overheating the engine can all help prevent a blown head gasket.
If you suspect that your 6.7 Cummins engine has a blown head gasket, be sure to have it inspected by a qualified mechanic and address the issue promptly to avoid costly repairs in the future.