Phone: 503-982-5516 or 503-481-2737

To start with, monitoring both ECT and EOT is an essential first step. this should be done during a test drive. The two temps should not show a difference of more than about 10 to 15 deg. F. The next step would be to pressure test the system while engine is at or near operating temperature. If there is a drop in pressure, remove the egr valve, raise the back of the vehicle at leat 16", and look for coolant in the intake manifold. This test is not always conclusive as sometimes the EGR cooler will only leak during engine operation, or during hot soak to cooldown periods such as when sitting overnight.

Assuming you have no obvious external coolant leaks, the best method for determining a failed head gasket is to remove the intake manifold and EGR cooler, and bench test the cooler with a vaccum pump. Next, plug the coolant outlet on the oil cooler with a 5/8" cap and hose clamp, cap off the EGR cooler de-gas line at de-gas bottle and plug the intake to front cover passage with a 3/4" expandable rubber freeze plug. Pressurize the cooling system to 16 psi, then listen for escaping air in all the intake ports, and in the EGR cooler connection on the exhaust up-pipes. Any air heard indicates a leak between the cooling system and the combustion chambers. You could rotate the engine by hand a few times to ensure the valves on any leaking cylinders are open, but chances are you will hear the escaping air without doing this. there are other methods of diagnosing a failed head gasket, but this one seems to be the most conclusive and you should replace the EGR cooler with an upgraded Bulletproof cooler regardless. We have also used a cooling system combustion leak detector tool, but have yet to see a conclusive result from this method, or at least a result that made me comfortable in tearing the engine down at that point. Another method that we sometimes use is to "sniff" the air in the degas bottle with a five gas analyzer looking for C02,CO and HC. any level of these gases are a pretty conclusive indication there are combustion gasses entering the cooling system. this method works especially well in the early stages of head gasket failure which as stated earlier, can be extremely difficult to diagnose.

If you are blowing coolant only when pulling a load, there is a chance that combustion pressures entering the cooling system. In such a case, it may be impossible to do a proper leak test of the cooling system to identify the leak, and a combustion leak detector may be the only option for diagnosis for the average DYI'er.  A leaking EGR cooler may result in combustion gases in the cooling system, so the EGR cooler should still be bench-tested to ensure it is not the source of the leak.

The stock head gasket is a five layer, laminated stainless steel gasket with  sealing beads on the top and bottom surfaces. and one side of the center surfaces.. The layers  rely on head bolt tension to keep them compressed and sealed. We use black onyx head gaskets. these gaskets have a sealing materialover the entire surface, and do a much better job of sealing both the cylinder, and the water passages as well.

 It is believed that head gasket failures are often caused by a restricted oil cooler, which feeds coolant to the EGR cooler, causing low coolant flow to the EGR cooler. Low coolant flow can cause the coolant in the EGR cooler to boil, bursting the cooler. This results in a leak, and therefore a low coolant condition.. This is true in some cases, but we have also found failed head gaskets on stock 6.0's in which the EGR cooler was intact and passed the bench test. In this case, it is due to head bolt stretch. These bolts are 12mm x 190mm in length. The threads on the bolts measure about 110mm of the total length, with approx. 30mm actually threading into the cylinder block. This leaves about 70 mm or so of thread to weaken the bolt. These bolts are torque-to-yield, meaning they are installed and torqued, then turned a certain number of degrees beyond that point. This works well in a 6.0L with 250 hp, to be used in a medium-duty truck chassis, but cannot stand up to the higher horsepower, and resultant heat the occures when Ford engineers tuned the  fuel system for use in the F Series.

Under the stresses of tens of  thousands of thermal cycles, and given the high boost and combustion pressures, these bolts will lose their tension and allow combustion gases to enter the cooling system between the laminated layers of the head gaskets, ultimately resulting in total head gasket failure. It is even quite possibe for a 6.0 liter to be in the early stages of head gasket failure without the common symptoms. we have found a percentage of 6.0 liter's in which we have done a preventive head gasket/stud install, are already in the early stages of failure. we have found head gasket failure on 6.0 liters with as little as twenty thousand miles, but the most common failures are occuring in the eighty to one hundred thousand mile range. It had been rumored that ford upgraded the 6.0 head bolts in late 2005, and that 05/07 trucks dont blow head gaskets, this is not true. we are seeing more than a fair amount of 05/06 failures, and will surely see the 07's as well.

We strongly recommend the installation of cylinder head studs in all 6.0 liter Powerstroke diesels. If your truck is still under warranty and you have a head gasket failure, I would suggest you inquire whether or not the dealer will install studs if you buy them. I know many dealerships will do this. If your truck is out of warranty, you must decide if you want to chance a failure, or go ahead and get it done before they fail. It is a pretty expensive procedure but when combined with the installation of an upgraded EGR cooler, new oil cooler and a coolant filtration system, it will minimize the chance for failure, and make your truck many times more reliable for years to come. Lets face it, these trucks are expensive, and with the cost of buying a new Super Duty and the questions regarding their reliability, upgrading a few components on your current truck can make good economic sense.

We sell and install ARP head stud kits, the Bulletproof upgraded EGR cooler, engine oil coolers, and our own coolant bypass filtration systems. For prices and information visit our Ford Parts page or give us a call today. 503-657-5306

Rob Gaskell, Sr.
Owner
Fleet Service Northwest

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