6.0L Head Gasket Failure

by Rob Gaskell, Jr. and Rob Gaskell, Sr.

Experience has shown that at some point in the service life of the vehicle, it is likely that owners of the 6.0L Powerstroke will experience head gasket failure, and those with performance tuners installed are likely to experience this problem at very low mileage. At Fleet Service Northwest we have seen a trend for trucks with stock tunes failing at between 70,000 and 150,000 miles, and those with performance tuners failing at 22,000 to 80,000 miles or so.

When this issue is to be repaired, it is important that certain steps are taken to prevent repeat failure, and to address other potential problems while the engine is disassembled for head gasket replacement. These include installation of ARP Head Studs, careful cylinder head inspection, updating HPOP parts, and replacement of additional gaskets and seals that may lead to repeat failures if left unaddressed. Preventive installation of ARP Head Studs is also a great option for those who would like to avoid the inconvenience and risk of additional damage of blown head gaskets, since proper ARP Head Stud installation has proven to be a reliable long-term fix for this serious 6 Liter problem.

The Issues

The 6L Powerstroke suffers widely from head gasket failure, also known as "blown head gaskets," which can be ultimately attributed to stretching of the cylinder head bolts, resulting in a lack of sufficient clamping force between the cylinder head, gasket, and engine block. There are several factors that contribute to this stretching, some of which are serious problems that can be addressed through upgrades of their own. The best way to prevent head gasket failure on the 6L is to install ARP Head Studs preventively. Barring a preventive installation of head studs, avoiding performance tuners until head studs can be installed and maintaining and upgrading the EGR and engine oil cooler are important steps to prolonging cylinder head gasket life.

Degas Bottle/Radiator Cap Issues

Before condemning the head gaskets after this kind of coolant expulsion, the integrity of the radiator cap and degas bottle must be tested. The system should be pressure tested by adapting a coolant tester to one of the hoses which connect to the top of the degas bottle, rather than testing the cap separately. This will allow the performance of the sealing surfaces between the cap and degas bottle to be tested, as well as testing for leaks throughout the rest of the system. It is not uncommon for the degas bottle to crack at the seam between top and bottom. This may or may not be a result of overpressurization/overheating due to head gasket failure, and therefore head gasket should be considered as a possibility even if the degas bottle is cracked. Additionally, there is a revised fill level decal for the cooling system, which places the max fill level at the original min fill mark, and the new min fill mark at 5/8" lower than before. The new system fill level should be maintained whether the revised decal is present or not.

Stock Head Bolt Issues

The 6.0L Powerstroke has ten cylinder head bolts per head, and are installed at the factory using a torque-to-yield method. Torque-to-yield attempts to gain the maximum amount of clamping force from a bolt without damaging it and attempts to provide a more consistent clamping force across all ten bolts. This is done by initially tightening the bolts to a low torque, then turning each of them by a certain uniform angle. As the bolts turn through this angle, the distance between the head of the bolt and the engine block changes a predictable amount due to the pitch of the bolt threads. This method eliminates the unpredictable effects of friction which causes inconsistent clamping force for a given torque, as described in our ARP Head Stud Torque article.

There had been rumors about supposed head bolt or gasket improvement on later-model 6.0L trucks, starting with claims about the immunity of the 2005 model year to head gasket failure, with many owners and other concerned individuals later suggesting that the 2007 6.0L is immune from leaking head gaskets as the 2005 and 2006 model years showed widespread failures. In 2012, it is already quite apparent that the theories regarding the immunity of any of the 6.0L models were wishful thinking.

Head bolts can potentially stretch due to the heating and cooling cycles that all engines go through, which cause the bolts and cylinder heads to expand and contract. As the cylinder head expands and contracts, it can potentially increase the force on the bolt, causing it to stretch in a way that it will not recover from when the metal components cool. The head bolts on the 6.0L are designed to provide a sufficient clamping force around the cylinders and combustion chambers so that the high combustion pressures produced by the turbo diesel under heavy loads cannot escape. The head bolts are generally successful at providing this clamping force for a time, and some trucks have made it as far as 150,000 miles or more without a sign of head gasket leak. Many trucks experience this failure at significantly lower mileage, however, since the head bolts are simply not strong enough and do not have a large enough safety factor in the clamping force they are able to provide.

Engine Oil Cooler Issues

The two most common failures of this cooler include; clogging of the coolant passages due to deposits, which form as a result of contaminated or unmaintained coolant, and internal leakage between the coolant and oil passages. The first of these issues, clogging of the coolant passages, results in a higher than normal engine oil temperature. The best way to prevent damage due to unnoticed engine oil cooler clogging is to have the vehicle maintained by a qualified repair facility that inspects engine oil operating temperatures regularly and is qualified to recognize signs of trouble, as well as performing cooling system flushes approximately every two years, depending on usage.

This failure can lead to premature engine wear, fuel injector failure, and localized overheating of engine components. Engine oil in the 6L is used not only as a lubricant but also as a high-pressure hydraulic fluid in fuel injector operation. Engine oil is also used as a method of cooling engine components such as pistons, adding to the threat of localized overheating. This localized overheating is typically not indicated by the engine coolant temperature gauge and may go unnoticed by the driver, increasing the importance of proper maintenance by a qualified facility. The latest software updates for the 6.0L contain enhanced cooling system monitoring. This is why it is important to keep your truck's control module software up to date. This new programs will better alert you to an overheating condition by changes in the temperature gauge if high engine oil temperatures are present. This condition will also set a trouble code, and turn on the amber wrench light on the instrument cluster.

The second of the common oil cooler failures, leakage between the coolant and oil passages, is more serious and can lead to severe engine damage. The best way to prevent this failure is to eliminate the stock engine oil cooler and replace it with a Bulletproof Engine Oil Cooler, which is an air-to-oil rather than coolant-to-oil cooler. This eliminates the possibility that oil will leak into the cooling system since there is no longer a vulnerable connection between the two systems.

The most apparent symptom of a leaking engine oil cooler is the presence of oil in the coolant expansion bottle, as well as a milky appearance and consistency of engine oil or coolant. Since engine oil is under greater pressure than engine coolant, more oil typically enters the cooling system than coolant enters the engine crankcase. This oil contamination can cause sludge to build up in the cooling system, reducing cooling to critical engine parts, leading to localized overheating and premature failure of these parts. If left unnoticed, it can also reduce engine oil level and cause engine failure. Also, if enough coolant does enter the crankcase, it can contaminate and dilute the engine oil, removing its ability to lubricate engine components, leading to severe engine damage such as camshaft and crankshaft bearing failures, valve train damage, and injector failures.

EGR Cooler Issues

The 6.0Liter Powerstroke EGR cooler is mounted below the intake manifold on the right-hand side of the engine. This cooler is prone to rupturing, allowing coolant to leak into the exhaust system. This is often referred to as a "blown EGR cooler." The best way to prevent damage due to EGR cooler failure is to properly maintain or eliminate the stock engine oil cooler, as explained above, as well as to upgrade the EGR system with a Bulletproof EGR Cooler, which to date has never had a reported failure and features a lifetime warranty.

Common symptoms include steam from the exhaust while driving, as well as coolant loss with no evidence of external leakage. It is essential that possible head gasket leakage is ruled out if these symptoms are present, as either can be a sign of head gasket failure. The EGR Cooler uses engine coolant to cool exhaust gases which are reintroduced into the engine's intake to cool combustion temperatures and reduce nitrous oxide emissions. The EGR Cooler commonly fails due to overheating and boiling of the coolant inside it, rupturing it and causing coolant to leak into the exhaust manifold. This overheating in the cooler is sometimes caused by low coolant flow to the cooler since coolant must pass first through the stock engine oil cooler before it is delivered to the EGR cooler. As the engine oil cooler begins to clog, the EGR cooler is starved for coolant.

If the cooler leaks while the engine is not running, the coolant can enter engine cylinders through open exhaust valves. Attempting to start the engine after the coolant has entered a cylinder can lead to hydrolocking, where the incompressible coolant in the cylinder stops the engine from turning. The affected cylinder's connecting rod may bend as a result, requiring significant internal engine repairs or engine replacement to correct.

Performance Tuner Issues

Many 6Liter Powerstroke owners desire more horsepower, better towing performance, or better fuel economy from their Super Duty trucks. While there are an array of tuners available to address the desires of 6.0L owners, all tuners that increase horsepower and modify fuel delivery and turbocharger performance have one thing in common: they accelerate the occurrence of problems such as head gasket failure. The best way to prevent the head gasket failures that performance tuners contribute to is to preventively install ARP Head Studs and other upgrades.

Performance tuners increase fuel delivery rates and Variable Geometry Turbo (VGT) operation and may modify or eliminate EGR system operation as well. All of these modifications increase combustion temperatures and pressures, which can contribute to localized overheating near the cylinder head gaskets, as well as place a higher stress on the sealing connection between the cylinder head, gasket, and engine block. As described at the beginning of this article, 6.0L trucks with stock tunes typically see head gasket failures at 3 to 4 times the mileage as performance-tuned 6.0L trucks. The performance tuners and selected tunes used by the trucks seen experiencing low-mileage head gasket failure at Fleet Service Northwest represent a broad selection of tuner brands and options, including towing and economy tunes.

It is not our desire to warn 6.0L owners away from using performance and economy tunes, but rather to note the trend we've seen for tuners to accelerate the occurrence of some of the 6.0L's most severe reliability issues including head gasket failure. Many owners have been extremely happy with the added performance and economy which these tuners provide. These tuners do little more than accelerate problems that are likely to occur eventually regardless of tune, and problems for which Fleet Service Northwest has long-term answers for that can hold up to a wide variety of performance and economy tuners.

The Answers

Owners of the 6.0L Powerstroke often express a desire to replace their trucks with an earlier model Ford or another make, either due to a history of problems with their own truck or because of worry over potential problems that they have yet to experience. Because this is such a widespread attitude, the 6.0L-powered Super Duty has depreciated significantly in value, offering resale values which are relatively low compared to the very high purchase price the trucks originally demanded, leading to losses which are greater than the cost of maintenance and upgrades which significantly improve the reliability of the 6.0L. The upgrades and maintenance procedures related to head gasket failure recommended by Fleet Service Northwest, Inc. are the subject of this section.

Stock Head Bolt Answers

6.0L cylinder head gasket replacement using stock head bolts has proven itself over and over as a temporary repair, which will soon lead to an avoidable repeat failure. Installation of ARP Head Studs, on the other hand, is a necessary part of a proper head gasket replacement that has proven to be a long-term solution to 6.0L head gasket failure. It is essential that machining of the cylinder head surfaces is performed when replacing head gaskets, despite Ford's stance that the heads cannot be machined.

ARP Head Studs are made of a stronger steel, and torque tighter and are far less prone to stretching than stock head bolts. ARP head studs also engage fully into the threads in the engine block, reducing the stress and stretching of the threads which occurs while tightening the fasteners. A low-friction grease is applied to the threads, nut, and washer which are installed at the top of the head studs, reducing the torque required to provide the tension required to clamp the cylinder head and gasket to the engine block, as explained in our Head Stud Torque article.

Engine Oil Cooler Answers

As explained above, the engine oil cooler is a significant reliability issue with the 6.0L PSD. Fortunately, there is a permanent solution which has been developed by Bulletproof Diesel. The Bulletproof Diesel Engine Oil Cooler system for the 6.0L has proven to be a great improvement over the stock cooler, not only in its proven reliability but also in its improved cooling of engine oil.

The Bulletproof Engine Oil Cooler is an air-to-oil cooler which mounts to the rear of the air conditioning condenser. This mounting location allows optimal cooling of engine oil without reducing the performance of the vehicle's air conditioning system. Installation of this cooler helps reduce engine oil temperatures, especially when towing heavy loads and eliminates the recurring problems for which the stock engine oil cooler is notorious.

The Bulletproof Engine Oil Cooler kit includes everything which is necessary to install the engine oil cooler, including the oil transfer block, and remote-mounted engine oil filter system. The Full Bulletproof Kit also includes a Bulletproof EGR Cooler at a discounted price compared to buying the coolers separately.

EGR Cooler Answers

The EGR Cooler is another significant source of Powerstroke trouble which Bulletproof Diesel has addressed for both the 6.0L and 6.4L engines. For 6.0L's which still have stock EGR coolers, installation of a Bulletproof EGR Cooler should be a mandatory part of head gasket replacement, or of any other service which requires removal of the intake manifold. The Bulletproof EGR Coolers for both engines feature lifetime warranties and have already proven to be a great way to permanently solve an otherwise recurring problem with these engines. The Bulletproof coolers accomplish this through much more robust construction than the stock coolers, and by holding a higher volume of coolant, reducing the likelihood of coolant boiling within the cooler. This is done without taking up additional space in the engine compartment, as the Bulletproof EGR coolers are actually made by replacing the internal components in a stock cooler.

Performance Tuner Answers

Performance and economy tuners can add to the horsepower, fuel mileage and towing performance of a 6.0L Powerstroke, and add to the enjoyment and satisfaction owners get from driving their Super Duty trucks. When a 6.0L truck has been upgraded with ARP Head Studs and Bulletproof EGR and Engine Oil Coolers, the 6.0L/Super Duty platform can hold its own as one of the most durable and enjoyable trucks to drive, whether for occasional boat and camper trips, as the power plant for a mobile retirement home, or as a light commercial vehicle.

The Full Bulletproof Package

The Full Bulletproof Package is the most economical way to upgrade all of the 6.0L's most serious reliability issues, and includes ARP Head Stud installation combined with Bulletproof EGR and Engine Oil Cooler installation, all at once. The economy of this service comes from the elimination of significant repeated labor which would be required if performing each of these upgrades separately. Replacing the EGR cooler and replacing or upgrading the engine oil cooler both require removal of the intake manifold. The labor for these services accounts for approximately 1/3 of the labor required for head gasket replacement. This is one important reason that we recommend trucks receiving EGR and oil cooler replacement also receive and ARP Head Stud installation in combination with these repairs.

It has been our experience that many trucks which experience stock EGR cooler failure and do not receive ARP Head Stud installation at the same time, will experience head gasket failure in a short period of time following EGR cooler failure. This may be attributed to the EGR cooler failure itself, as described above, as well as to the general problem of 6.0L head gasket failure. Even if EGR cooler failure has not contributed in a significant way to head gasket failure, it is a predictable and preventable failure which is more economical to address preventively in combination with, rather than separate from, EGR and engine oil cooler upgrade and repair.

The Decision

Now that we've gone through the 6.0L's EGR and engine oil cooler problems, and the recommended repairs, it may seem to some owners that these trucks aren't worth keeping due to high maintenance costs, especially if you're facing one of these issues at this time. It is important to take all factors into account when considering replacing a truck since even major repairs are usually a more economical choice. The biggest factor is, of course, the purchase price of a new or used truck compared to the trade-in value of a 6.0L-powered truck. As mentioned before, the value of these trucks has depreciated due to their widespread problems, and the resulting desire of many owners to replace them with Duramax and Cummins-powered trucks, or other Ford trucks that matter, has helped keep the resale value of these other trucks high. A new truck payment may be $700 or more and still requires periodic preventive maintenance, meaning that a new truck may cost $10,000 a year just in payments and maintenance for the first few years.

Most 6.0L trucks are paid for by now or are nearly paid for, and even in some worst-case scenarios, average yearly maintenance will not come close to the cost of a new truck. Add this to the fact that the Ford Super Duty chassis is more robust and more capable than any other chassis in the light truck market. The powertrains on other trucks may lack the major reliability issues, but the trucks themselves just don't measure up to the legendary Super Duty platform.

If repairs and upgrades are performed correctly, and the preventive maintenance procedures recommended in this article and by the manufacturer are performed, the 6.0L Powerstroke can serve its owners economically for years to come. This means that the only reason to get rid of most 6.0L-powered trucks is that you are willing to pay more to have something different, or because you no longer need a truck and won't be replacing it. As the saying goes, it's usually worth more to you, than it is to anyone else.

Rob's Powerstroke Performance Center, 6.0l/6.4l Diesel Specialist, 6.6l Duramax Diesel Specialist

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