GMC 4000 Series Service Manual page 301

Sec. 6B
Page 290
TORO-FLOW DIESEL ENGINE
Figure 1 — Air Filter in Ventilation Tube
6. Start engine and check for oil leaks at shell
gasket and retaining bolt.
7. Stop engine, allow a few minutes for oil to
drain into oil pan; recheck oil level on dipstick. If
n ecessary, add oil to raise level to "FULL" mark.
NOTE: Recommendations for oil change per­
iods, oil specifications, and viscosity are contained
in LUBRICATION (SEC. 0) of this manual.
CRANKCASE OIL LEVEL AND
VISCOSITY OBSERVATION
A bayonet-type oil level gauge at right side of
engine is provided for checking crankcase oil level.
This gauge is marked "ADD" and "FULL."
Daily, or oftener if necessary, check crank­
case oil level. Make oil level check preferably
after a day's run and after engine has been stopped
for at least five minutes. Remove dipstick, wipe
clean with cloth, reinsert dipstick, then remove
again. Oil level should be maintained between
"ADD" and "FULL" marks without overfilling. Do
not operate with level below "ADD" mark. Add oil
whenever the oil level reaches or falls below the
"ADD" mark.
When checking engine oil level, make note of
oil viscosity. If there is evidence of crankcase oil
dilution as indicated by oil appearing too "thin" or
by level above the "FULL" mark on dipstick, make
necessary investigation to determine cause of di­
lution and make necessary corrections.
DRIVE BELTS
Inspect all drive belts for evidence of worn or
frayed condition as well as for other damage. Re­
place belts if worn.
NOTE: Belts used in pairs must be replaced
as a matched pair. Follow instructions given in
ENGINE COOLING SYSTEM (SEC. 6K) of this
manual for replacing and/or adjusting drive belts.
G M C S E R V I C E M A N U A L
FUEL SYSTEM
and injection units for evidence of leaks and dam­
age. Repair as necessary.
SYSTEM (SEC. 6M) for detailed information on
fuel filters, injection pump assembly, control
mechanism and servicing fuel injection nozzles.
Recommendations pertaining to fuel system service
intervals are contained in applicable "Owner's and
Driver's Manual."
in cold weather, refer to suggested remedies in
"Trouble Diagnosis" under "Hard Starting."
CRANKCASE VENTILATION SYSTEM
is employed on Toro-Flow engines. The opening for
escape of blow-by gases is through a baffled oil
separator installed in cylinder block at rear of
left-hand bank of cylinders.
in road draft tube near lower end.
filter element should be made to assure free flow
of gases. To clean filter element remove from
engine, wash in solvent and reinstall.
check battery electrolyte specific gravity at each
cell to be sure battery is fully charged. Add water
and charge battery as necessary.
PRELIMINARY TEST OF
CYLINDER COMPRESSION
on one or more cylinders, the following test should
be made to determine which cylinders may be at
fault;
temperature is reached.
clamps. Remove the high p ressure line between
injection pump and nozzle holder at cylinder to be
checked. Use care not to bend the high pressure
line when removing. Remove the nut at each end
from the threads at pump and nozzle holder and
lift the line away from both units without bending.
on injection nozzle holder. Remove nozzle holder
retaining bolts and pull the holder assembly out of
well in cylinder head. Clean nozzle holder cavity
and gasket seat in cylinder head, then turn engine
Make periodic inspection of fuel filters, lines,
Refer to applicable portion of ENGINE FUEL
NOTE: In case of complaints of hard starting
Road draft type crankcase ventilation system
A filter element assembly (fig. 1) is installed
A periodical inspection of road draft tube and
CHECKS PRIOR TO TUNE-UP
Before performing other tune-up procedure,
In case there is evidence of low compression
1. Start engine and run until normal operating
2. Stop engine and remove high pressure line
3. Disconnect leak-off hoses from tee or elbow