Chevrolet DB90 Series, Service Manual

Page: 75 / 242

Sec. 6C-69
53 AND 71 SERIES DIESEL ENGINES
o h
A P n a b le m A w c M fU i
(53 AND 71 SERIES DIESEL ENGINES)
C ertain abnorm al conditions which so m e tim e s in terfere with s a t is ­
factory engine operation, together with methods of determ ining cause
of such conditions, a re covered on the follow ing p ages.
Contents of th is sectio n are liste d in Index below:
Locating a M isfiring Cylinder • • 69
Engine Oil P r e s s u r e T e st •
74
Checking C om pression P r e ssu r e 70
Cooling S y s t e m .....................
74
Fuel Quality .................................... 71
A ir B ox P r e s s u r e T est • • .
75
Engine Out of F u e l ........................ 72
A ir Intake R estrictio n T est
75
F uel Flow T est .............................. 72
Exhaust B ack P r e s s u r e T est 76
Fuel P r e s s u r e T est ..................... 73
P rop er U se of M anometer .
77
C rankcase P r e s s u r e T est • • • • 73
P r e s s u r e C onversion Chart
77
O il, F uel, and Coolant Leak Trouble Shooting
Gasket I n s t a lla t io n ................................................ 78
Cleaning Injector Spray T i p .............................. 79
SATISFACTORY ENGINE OPERATION
DEPENDS PRIMARILY ON:
1. The p r e se n c e of an adequate supply of air
co m p ressed to a su fficien tly high com p ression
p r e ssu r e .
2. The injection of the proper amount of fuel
at the right tim e.
Lack of pow er, uneven running, e x c e s s iv e v i­
bration, stallin g at idle speed, and hard starting,
may be caused by eith er low com p ression , faulty
injection in one or m ore cylin d ers, or lack of su f­
ficien t a ir.
Since proper com p ression , fuel injection and
the proper amount of a ir are important to good
engine perform ance, detailed procedures for th eir
in vestigation are given la te r.
A te st panel may be fabricated lo ca lly a s shown
in figu re 10. T his would enable te s ts to be made
with one hook up.
Figure 11 show s T est Kit (J-9531-01) with
hand tachom eter and figu re 12 shows T e st Kit
(J-22506) with e le c tr ic tachom eter. A lso , in th ese
D ie s e l T est Kits a re gauges, h o ses, and adapters,
for making various te s t s . The in stru ction s on the
follow ing p ages show the various te sts and a n a ly sis
which can be made.
LOCATING A MISFIRING CYLINDER
(Refer to F ig. 13)
1. Start the engine and run it at part load until
it rea ch es norm al operating tem perature.
2. Stop the engine and rem ove the valve rocker
co v e r (s). D isca rd the gask et(s).
3. Check the valve clea ra n ce 0.024" for the
53 S e r ie s engine and 0.014" for 71 S e r ie s engine
as d escrib ed in S erv ice Manual ST 135-70, Section
6C.
Figure 10 —Test Panel (Fabricate Locally)
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT .