1948-1952 Shop Service Manual - - Hudson-Essex-Terraplane Club

ENGINE TUNE-UP 2 -5
5. After completing amperage draw test, turn tester control
knob to " OFF" position.
NOTE: Excessively high readings will indicate a short in
the starting motor circuit or an excessive drag on the motor
due to a bent armature shaft or the field coils touching the
armature. Low readings indicate excessive resistance in the
circuit caused by loose connections, worn brushes, or weak
brush spring tension.
CYLINDER BALANCE TEST
The Cylinder Balance Tester compares the evenness of the
power output of each cylinder in the engine.
To isolate one weak cylinder, short out half the cylinders.
The half giving the lower reading will include the weak
cylinder.
Air bubbles prevalent in the radiator filler neck (radiator
filled with coolant to the over-flow pipe) indicates a leaking
cylinder head gasket, cylinder head or internal cracks in the
water jackets.
An extreme blow-by at the oil filler pipe indicates defective
piston rings. (Compression pressures by-passing the piston
rings).
COMPRESSION
Compression should be checked with a reliable compression
gauge and with the engine at operating temperature
(ignition switch off ).
1. Remove foreign matter around spark plugs. Loosen spark
plugs about one turn to break free any accumulated carbon,
start the engine and accelerate to 1000 R.P.M. to blow
out the carbon. Stop the engine and remove the spark plugs
placing them in the order that they were removed.
FIGURE 7
1. Connect the vacuum gauge and tachometer as shown in
Figure 7, and set the throttle until engine is running at 1500
R.P.M.
2. Ground the master clip of the cylinder balance tester and
connect individual leads to spark plugs 2-3-4 and 5. Engine
will now be running on cylinders 1 and 6.
3. Note the reading on the vacuum gauge. Make the same test
on each pair of cylinders in the following sequence.
6 cylinder 1-6, 2-5, 3-4
8 cylinder 1-8, 3-5, 4-7, 2-8
NOTE: A variation of more than 1 inch of vacuum or 40
R.P.M. between pairs of cylinders being tested indicates
either a defective plug or unequal compression in a cylinder.
NOTE: Starting and accelerating the engine after the plugs
are loosened is very important to remove loose carbon and
prevent the carbon flakes falling on the piston crown and
around the valve.
2. Insert the compression gauge in each spark plug hole in
turn and crank engine with J-2679 Remote Control
Switch. Crank engine for at least 4 compression strokes.
Note reading on the first as well as final stroke.
3. Compression at each cylinder should be at least 100
pounds. Compression between cylinders should not vary
more than 10 lbs.
NOTE: If the compression gauge moves up in jerky steps
of 10 or 20 pounds at a time, it generally indicates a sticking
or leaking valve. If two adjacent cylinders show low
compression readings, check for a leaking cylinder head
gasket or loose cylinder head.