cylinder blocks, main bearing plate and the spark plugs
Ignition spark timed wrong. See 'Magneto Timing'.
to the specified torque readings indicated in the
following paragraphs of reassembly.
Low grade of gasoline.
While the engine is partly or fully dismantled, all of the
parts should be thoroughly cleaned.
Restricted cooling air circulation.
accumulated dirt between the fins.
Part of air shroud removed from engine.
If it is desired to disassemble the engine, the following
Dirt between cooling fins on cylinder or head.
order should be substantially adhered to.
disassembly progresses, the order may be altered
Engine operated in confined space where cooling air is
somewhat if desired, as will be self-evident to the
continually recirculated, consequently becoming too hot.
mechanic. Reassembly of the engine should be made
Carbon in engine.
in the reverse order.
TESTING REBUILT ENGINE
An engine that has been completely overhauled, such
Engine operated while detonating due to low octane
as having the cylinders rebored and fitted with new
gasoline or heavy load at low speed.
pistons, rings and valves, should go through a thorough
"run-in" period, before any amount of load is applied to
Poor grade of gasoline or of low octane rating.
The engine should be started and allowed to run for
about one-half hour, at about 1200 to 1400 R.P.M.
Engine operating under heavy load at low speed.
without load. The R.P.M. should then be increased to
Carbon or lead deposits in cylinder head.
engine operating speed, still without load, for an
additional three and one-half to four hours.
Spark advanced too far. See 'Magneto Timing'
The proper 'running-in" of the engine will help to
Loose or burnt out connecting rod bearing.
establish polished bearing surfaces and proper
Engine overheated due to causes under previous
clearances between the various operating parts and thus
add years of trouble free service to the life of your
Worn or loose piston pin.
ENGINE BACKFIRES THROUGH CARBURETOR
Water or dirt in gasoline.
The air cleaner, oil filter, magneto, electric starter and
Poor grade of gasoline.
After the flywheel screen has been removed, drive out
Sticky inlet valves. See 'Valves'
the pin in the crankshaft and remove the flywheel nut
Spark plugs too hot. See 'Spark Plug'.
The flywheel is mounted to a taper on the crankshaft.
Hot carbon particles in engine.
Take a firm hold on the flywheel fins, pull outward and
at the same time strike the end of the crankshaft with a
babbitt hammer, see Fig. 10. The flywheel will slide off
DISASSEMBLY AND REASSEMBLY OF VH4D
the taper of the crankshaft. Do not use a hard hammer
as it may ruin the crankshaft and bearings. When
Engine repairs should be made only by a mechanic who
reassembling the flywheel, be sure the Woodruff key is
has had experience in such work. When disassembling
in position on the shaft and that the keyway in the
the engine, it is advisable to have several boxes
flywheel is lined up accurately with the key.
available so that parts belonging to certain groups can
be kept together, such as, for instance, the cylinder
To disassemble air shrouding, refer to Fig. 11. First
head screws, etc. Capscrews of various lengths are
remove cylinder head covers and the screws mounting
used in the engine, therefore great care must be
the flywheel shroud to the lower cylinder shrouds and
exercised in reassembly so the right screw will be used
cylinder heat deflectors, then remove the screws holding
in the various places, otherwise damage may result.
the flywheel shroud to gear cover.
Tighten the capscrews and nuts of the manifolds,
cylinder heads, gear cover, oil pan, connecting rods,