9th. From the Kingston injection valve not being properly opened, or from its outside orifice being choked.
10th. The bilge injection may be so connected with the air pump or condenser as to impair the vacuum when its valve is accidentally stuck and its stop cock is left open.[66]
[66] It is obvious that a defective vacuum may or may not prevent an engine from starting, according to the degree of defectiveness.
The principal causes of heating are:
1st. The bearing caps being screwed down too tight.
2d. The bearings being left uncovered, thus allowing the brick dust used for cleaning the machinery, the dirt from coaling the ship, or the sand used for cleaning the decks, to get into the bearing.
3d. The oil grooves in the brasses being worn out or too shallow, or the brasses not being cleared at the sides.
4th. Improper fitting of the distance pieces or fit strips between the brasses.
5th. Bad oil or too light an oil.
6th. If the brasses are too slack and thump or pound, the back of the brass may be stretched by pening, causing the sides of the brass to close in upon and bind the crank journal or crank pin, and this will cause heating.