A blown out cylinder head gasket can invariably be traced to failure to securely tighten cylinder head nuts, particularly during the first 50 miles a new car is driven. During this period the new cylinder head gasket becomes slightly compressed, as a result all of the cylinder head nuts can be taken up several times until the gasket obtains a permanent set. This also applies when a new cylinder head gasket is installed in an old car.
After completing a drive-away trip, instruct your mechanics to go over all of the cylinder head nuts and see that they are securely tightened. An additional check should also be made before delivering the new car to the owner, and again when the car is brought in for inspection.
The nuts should be tightened with the engine thoroughly warmed up. When tighten- ing the nuts it is of course understood that excessive force should not be applied, as there would be a possibility of damaging either a stud or nut.