Solving Ford 6.0L V8 Diesel Head Gasket Failures

The Ford 6.0 L diesel V8 engine was introduced in the mid-2003 production year, and ended in 2007 for most applications where it was offered.  It has been an engine with a reputation for problems through its relatively short production life, although as the engine received upgrades, and proper repairs, it became more reliable.    One major problem has centered on cylinder head gasket failures.

One of the major culprits here was the factory TTY (Torque to Yield) head bolts.  The TTY bolts are considered to be ‘one-time use’ products, and if they are removed from the engine for any reason, they must be replaced with new fasteners.  This is true in any application where TTY bolts are used.

The gasket failures could be caused by re-use of TTY fasteners, but also can be caused by failure of the oil cooler, an Exhaust Gas Recirculation (EGR) cooler failure, as well as performance add-ons… all of which will lead to increased cylinder pressures.  These cause the TTY fasteners to fail prematurely, since the bolts are stretched beyond their yield specs, and the head gasket will soon fail.

The installation procedure for replacing the OEM TTY head bolts can be relatively simple, to complex.

The question becomes:  Are you replacing the TTY bolts as a preventative maintenance procedure, or is this a repair caused by one of the three factors mentioned above.  Regardless of the situation, because the early examples of the engine is prone to the failure of the oil cooler and/or EGR cooler, it is advisable to consider these as Achilles heels for the engine.  Even a preventative maintenance head bolt replacement, should probably include replacement of those two components to avoid a failure in the future.

And, if you are considering a performance upgrade, replacement of the TTY head bolts becomes a “must do” item.

Solutions

While the most straightforward approach to the gasket/bolt failure is to get a new OEM gasket and TTY bolts, the solution itself is more complex.

If the underlying cause of the failure is one (or both) of the above mentioned coolers, they must be replaced before addressing the head gasket situation.  In the case of adding performance enhancements, they must be replaced with new, better than stock parts and find a stronger, more reliable fastener and gasket solution.  Both components in early engines were particularly vulnerable to design failure, and there are several aftermarket replacements which overcome the problems.

Given the track record of head gasket failure on the 6.0L Ford diesel engine, the smart money would be to eliminate all of the weaknesses – head bolts, the gaskets, the oil cooler and EGR cooler.  Servicing both areas requires removal of the valley cover for the oil cooler/filter assembly, and the intake manifold for the ERG cooler.  Many experts suggest removal of the truck cab to make the job easier, but there are head bolt replacement videos which outline how to do the job with the cab in place.

If you are going to replace the head bolts or the bolts and gaskets, you will need to pull the heads off the block after draining all of the engine’s coolant and oil.

After the head is off, both the head and block surfaces need to be cleaned.  After that is complete, each head bolt hole in the block needs to have the a thread chaser run down into each hole to the bottom to remove any debris, then blown clean with a blast of high pressure compressed air.  Before installing (or reinstalling) the head gasket, the cylinder bores and piston tops should be wiped cleaned using a clean, no-lint cloth and an engine cleaning solvent.  Using a steel straight-edge, check that the matching machined surfaces of the block and the head are perfectly flat.  Any warpage must be re-machined, to true the surfaces, or purchase remanufactured heads from a reputable supplier.

Before reassembling the heads to the block, you need to source high-quality head studs and fasteners to assure a trouble-free installation.  One company, Performance Quotient^®, a division of PRW Industries^®, offers a solution which focuses on the use of exceptional quality head studs, washers and nuts to clamp the head to the cylinder block.

The core of the Performance Quotient solution is the use of heat-treated, high-strength Custom 4135 Grade 12.9 Alloy Steel Cylinder Head Studs.  Each PQ^x® #101420 Ford 6.0L Diesel Head Stud Kit contains the required 20 – M14-2.0 x 33.85mm (9/16″-18 x 1.33″) studs, having a shank outside diameter of 13.44mm (0.53”) and an overall length  of 8.8125″, 20 – Custom 4135 Grade 12.9 Alloy Steel parallel ground washers and 20 – 12-point 9/16”-18 Custom 4135 Grade 12.9 Alloy nuts.  Additionally, the kit provides the installer with a 2 ml bullet of medium strength (blue) PRW Threadlocker and 0.5 oz. packet of PRW’s CMD Extreme Pressure Assembly Lube.

These studs are centerless ground to assure uniform diameters, and feature rolled threads for greater strength and thread conformity to the block holes (as compared to cut threads).  All studs, washers and nuts feature black oxide protective coatings.

The studs should be installed using the installer’s preference of threadlocker or engine oil.  The studs should be installed in the block finger tight initially, and if desired, snugged into place using the proper Torx driver, using the holes in the end of the stud.

It is advisable to use a new OEM replacement head gasket set (or a performance grade gasket if increasing power, or doing heavy towing).   The intake and valve cover gaskets must be replaced as well, and again, use OEM or better gaskets for best results.  While the factory may not specify that the turbocharger be serviced at this time, it has already removed, and probably should be cleaned, serviced and the seals and gaskets replaced before reinstallation.

PRW assembly lube should be used to install the washers and nuts, coating both sides of the washers and the threads.  Following the recommended tightening sequence, PRW recommends a four-step torqueing process – two rounds at 90 ft-lbs, loosening the nuts after each round, then retorque.  Then loosen the nuts and retorque to 130 ft-lbs, and finally loosen all nuts and retorque to 180 ft-lbs. to complete the installation.  This procedure is identical both for a new, replacement gasket, or re-installing the old head gasket.

The installation of new head studs on the 2003-07 Ford 6.0 L Diesel V8 diesel engine is indeed a long process when compared to a similar installation on a gasoline engine.  However, the piece of mind and operational longevity makes the investment of time, labor and material well worth it.