S3 AND 71 SERIES DIESEL ENGINES 6C-49
DIAGNOSIS AND TROUBLESHOOTING
(53 AND 71 SERIES DIESEL ENGINES)
Contents of th is sectio n a re lis te d in Index below:
TESTING AND DIAGNOSIS
Locating a M isfiring Cylinder
Checking C om pression P r e ssu r e
Engine Out of Fuel
F uel Flow T est
F uel Quality
Fuel P r e ssu r e T est
Engine O il P r e s s u r e T est
Cooling System
C rankcase P r e s s u r e
Exhaust Back P r e s s u r e
A ir B ox P r e s s u r e
A ir Inlet R estrictio n
P rop er U se of M anometer
TROUBLESHOOTING
Hard Starting
Low Starting Rpm
Low C om pression
Fuel
Abnormal Engine Operation
Uneven Running o r Frequent Stalling
Detonation
Lack of Pow er
Exhaust Smoke A n alysis
B lack o r Grey Smoke
Blue Smoke
White Smoke
No Fuel or Insufficient Fuel
A ir Leaks
Fuel Flow
Faulty Fuel Pump
High Lubricating O il Consumption
E xternal Leaks
Internal Leaks
Oil Control at Cylinder
Low O il P r e ssu r e
Lubrication Oil
P r e s s u r e Gauge
C irculation
O il
Pump
E x c e ssiv e C rankcase P r e s s u r e
Cylinder B low -B y
B reather R estrictio n
A ir F rom B low er or A ir Box
E x c e ssiv e Exhaust B ack P r e ssu r e
Abnormal Engine Coolant T em peratures
Above N orm al Operating T em peratures
B elow Norm al
TESTING AND DIAGNOSIS
Certain abnorm al conditions which so m etim es
in terfere with sa tisfa cto ry engine operation, to
gether with methods of determ ining cau se of such
conditions, are covered on the follow ing pages.
SATISFACTORY ENGINE OPERATION
DEPENDS PRIMARILY ON:
1. The p r e se n c e of an adequate supply of air
co m p re ssed to a su fficien tly high com p ression
p r e s s u r e .
2. The injection of the proper amount of fuel
at the right tim e.
L ack of pow er, uneven running, e x c e s s iv e v i
bration, stallin g at idle sp eed , and hard starting,
may be caused by either low com p ression , faulty
injection in one or m ore cy lin d ers, or lack of su f
fic ien t air.
Since proper co m p ressio n , fuel injection and
the proper amount of a ir are im portant to good
engine perform an ce, detailed p roced u res for their
in vestigation a re given a s follow s:
LOCATING A MISFIRING CYLINDER
(R efer to F ig. 1)
1. Start the engine and run it at part load until
it reach es norm al operating tem perature.
2. Stop the engine and rem ove the valve rocker
c o v e r (s). D isca rd the gask et(s).
3. Check the valve clearan ce 0.024" for the
53 S e r ie s engine and 0.014” for 71 S e r ie s engine
a s d escrib ed e a r lie r in this sectio n .
4. Start the engine and hold an in jector fo l
low er down with a scre w d riv er, to prevent op er
ation of the in jector. If the cylinder has been m is
firin g , th ere w ill not be any noticeable difference
in the sound and operation of the engine. If the c y l
inder has been firing properly, th ere w ill be a
noticeable d ifference in the sound and operation
when the injector follow er is held down. This is
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL
Summary of Contents for 70 Series 1970
Page 1: ...CHEVROLET HEAVY DUTY TRUCK SERVICE MANUAL...
Page 9: ...LUBRICATION 0 2 CHEVROLET SERIES 70 90 HEAVY DUTY TRUCK SHOP MANUAL...
Page 11: ...LUBRICATION 0 4 CHEVROLET SERIES 70 90 HEAVY DUTY TRUCK SHOP MANUAL...
Page 13: ...LUBRICATION 0 6 CHEVROLET SERIES 70 90 HEAVY DUTY TRUCK SHOP MANUAL...
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