Hi. Thanks for using JA! I will try and help you out.
I have seen oil cooler and oil pans leak, thats for sure. But not the Orings in the head so much. Have you had other mechanical problems with your engine? What kind of oil pressure does your engine normally have?
Thanks for the information.
I was interested in what your oil pressure was in case is was higher than it should be. This would not have an effect on the cylinder head but it would on the oil cooler. If the relief valve in the oil pump is stuck closed, the system will have higher than normal oil pressure causing the oil cool gasket to fail prematurely.
The Injection Actuation Pressure system for the fuel system is constantly changing from 3000 to 870 psi. The O rings on these plugs endure alot of stress while dealing with this pressure. Not to mention the temperature of the engine going from 215 to ambient. Over time, the O rings begin to leak. Caterpillar has change the material content for these several times. The problem always gets better but eventually the oil will begin to seep out once again. The most important thing about these O rings to make sure to lubricate the O rings upon installation. When they are put on dry, they may get cut when the plugs are torqued.
Please let me know if you have any more questions.
The C7 fuel system was redesigned from the one used on 3126B engines. The 3126B engine used a HI300 design. Due to new emission laws, the HI300 was not able to meet the demands needed for the new laws. So the HI300B was born. This fuel system has 4 injection modes compared to the 2 the HI300 had. The injection actuation pressures also run higher than the HI 300 did.
I believe the new fuel system design used on C7 engines is the reason for the oil leaks.