Starting in 2007 Dodge replaced the 5.9 series engine with a new, larger 6.7 liter engine. This engine came with emissions and was designed to run hot in order to burn clean. To cool the extra heat that the emissions equipment produced Cummins engineering added extra coolant passages to the engine block and cylinder head down the center between each of the cylinders. While this provided extra cooling capacity it also weakened the mating surfaces, which in turn causes them to warp. Also the 6.7 engine uses a new multi layer steel design head gasket and while it is tougher, it is also less forgiving to any imperfections on the sealing surfaces. Once there is enough warpage, either at the head or block surface, usually anything above .004, combustion gases will enter the coolant system. This can cause overheating, overfilling of the coolant reservoir, blowing coolant on the ground, heater problems and erratic fluctuations of the coolant temperature gauge.
While there are a few solutions to repair this situation such as resurfacing the head and/or adding head studs, even with these steps taken, warpage will still occur as well as repeat failures of the gasket, which is quite common.
The solution that we have is to have the cylinder head resurfaced and then o- ringed. O ringing involves a precise groove cut into the surface of the head and then a stainless steel o ring is installed. The o ring now adds a secondary seal to the head gasket at the fire ring area which can absorb warpage and still maintain a compression seal.
At XL Mechanical Service we have invested in the precision tooling required to cut and install these o rings in-house so we have complete control over the entire process. The cutter is designed to work with a Cummins OE head gasket and the stainless steel rings once installed do not move or break. We have done dozens of 6.7 heads with zero repeat failures. This process works on the 5.9 engine as well in high boost applications such as twin turbos.
If you have a 6.7 Cummins engine with head gasket issues then call us to discuss your specific repair requirements.
