Unless this shows signs of blowing it will not require attention. If, however, there are signs of leakage examine the faces of the joint washer and if necessary fit a new one. Very carefully clean the surfaces and refit the cylinder head. Tighten the cylinder head nuts a little at a time so that the head is pulled down perfectly evenly. Be careful not to strain the nuts when tightening, as if considerable force is used it will be found that it may still be possible to go on turning the nuts but excessive pressure of this nature is quite unnecessary to hold the head securely and to make a satisfactory joint and may cause serious distortion.