36. Compressor head gasket
Restricted discharge line.
Clear restriction or replace line.
Loose head bolts.
Tighten evenly to a torque of 25-30 foot
Faulty compressor or
Check for rough or poorly machined
head or block surfaces. Replace necessary
Either too much fuel or not enough fuel for com-
bustion can be the cause of a problem in the fuel system.
Many times work is done on the fuel system
when the problem is really with some other part of the
engine. The source of the problem is difficult to find,
especially when smoke comes from the exhaust. Smoke
that comes from the exhaust can be caused by a bad
fuel injection valve, but it can also be caused by one or
more of the reasons that follow:
Not enough air for good combustion.
An overload at high altitude.
Oil leakage into combustion chamber.
Not enough compression.
FUEL SYSTEM INSPECTION
A problem with the components that send fuel to
the engine can cause low fuel pressure. This can
decrease engine performance.
Check the fuel level in the fuel tank. Look
at the cap for the fuel tank to make sure the
vent is not filled with dirt.
Check the fuel lines for fuel leakage. Be
sure the fuel supply line does not have a
restriction or a bad bend.
Install a new fuel filter. Clean the fuel
screen located in the inlet valve of the fuel
Remove any air that may be in the fuel
system. If there is air in the fuel system, use the prim-
ing pump and loosen the nuts holding the fuel lines tor
the outside of the cylinder head, one at a time. Do this
until fuel, without air, comes from the fuel line
CHECK ENGINE CYLINDERS SEPARATELY
An easy check can be made to find the cylinder
that runs rough (misfires) and causes black smoke to
come out of the exhaust pipe.
Run the engine at the speed that is the roughest.
Loosen the fuel line nut at a fuel injection pump. This will
stop the flow of fuel to that cylinder. Do this for each
cylinder until a loosened fuel line is found that makes no
difference in engine performance. Be sure to tighten
each fuel line nut after the test before the next fuel line
nut is loosened. Check each cylinder by this method.
When a cylinder is found where the loosened fuel line
nut does not make a difference in engine performance,
test the injection pump and fuel injection nozzle for that
Temperature of an exhaust manifold port, when
the engine runs at low idle speed, can also be an
indication of the condition of a fuel injection nozzle. Low
temperature at an exhaust manifold port is an indication
of no fuel to the cylinder. This can possibly be an
indication of a nozzle with a defect. Extra high
temperature at an exhaust manifold port can be an
indication of too much fuel to the cylinder, also caused by
a nozzle with a defect.
The most common defects found with the fuel
injection valves are:
Carbon on tip of the nozzle or in the nozzle
Do not test or disassemble nozzles unless you
have the correct service tools.
NOTE: Do not disassemble fuel nozzles before they
have been tested. See TESTING PENCIL-TYPE FUEL