ighth, block
the wheels or set the brakes solid, put reverse lever in corner, open
cylinder cocks and give the engine steam. If steam comes out of both
cylinder cocks, and testing valve shows it is tight, then the packing is
blowing. Cylinder packing should be tested with steam first on one side
of the piston and then on the other.

77. Q. If engine should blow badly and be unable to start the train when
on the right dead center, on which side would be the blow generally?

A. On the left side. If the side standing on the quarter cannot start
the train, the trouble is usually there.

78. Q. If throttle were closed and steam came out of cylinder cocks,
what might be the cause?

A. To test for this, first shut off steam connection to the lubricator;
steam leaking into the cylinders can come from a leaky throttle or leaky
dry pipe.

79. Q. Is it possible to distinguish between a leaky throttle and a
leaky dry pipe?

A. Yes; a leaky throttle usually leaks steam at all times. A leaky dry
pipe will leak both steam and water. It will show a stream of water at
the cylinder cocks when the water level in the boiler is raised above
the leak in the dry pipe.

80. Q. What effect have leaky steam pipes in the smoke-arch, and how
should they be tested?

A. Leaky steam pipes waste steam and very seriously affect the draft in
the front end. A bad leak in the back part of the joint at the bottom
will blow into the tubes and make the engine smoke at the door with
throttle wide open while standing still. To test them, open the front
door and cover the joint with fine cinders. When the engine is given
steam, the cinders will blow away from the leak; to properly test them
in the shop, water under heavy pressure should be used.

81. Q. How should the test for a leaky exhaust pipe joint, or a leaky
nozzle joint be made?

A. About the only test that can be made on the road is to open the front
end and reverse the engine with throttle partly opened, watching the
suspected joint at the same time. For the bottom one with cinders around
the joint, for the top one it can sometimes be detected by holding a
torch near the joint.

82. Q. What should be done if a steam chest cracks?

A. Would loosen up the steam chest cover to free the sides, and wedge
between the studs and walls of chest, crowding the broken parts
together. A brake shoe key does this nicely. Would then tighten down on
steam chest cover and proceed.

83. Q. What should