Chevrolet 70 Series 1970, Service Manual

Page: 442 / 841

53 AND 71 SERIES DIESEL ENGINES 6C-45
ENGINE BRAKE TROUBLE DIAGNOSIS CHART (CONT’D)
PROBLEM
PROBABLE CAUSE
REMEDY
Supply housing so len o id s do not
control braking operation.
1. Solenoid s e a l m issin g , or
damaged.
1. In stall supply housing a s s e m ­
bly with functioning com pon­
ents.
Solenoids W ill Not E n ergize.
1. C ircuit breaker(fig. 34) open­
ing.
2. Switch at clutch le v e r an d /or
at buffer sc r e w failed , or
out-of-adjustm ent.
1. Check for sh ort circu it in
w iring. R epair w iring an d /or
rep lace circu it b reaker.
2. Adjust sw itch es for proper
operation. R eplace sw itch,
if defective.
Engine Bra^e Slow to O perate.
1. Lube o il cold and too thick.
2. Solenoid valve filte r sc r e e n
clogged, or s e a ls damaged.
3. Lube o il contaminated.
4. Switch operation slu g g ish .
1. A llow engine to w arm up b e­
fo r e operating b rak es.
2. In stall good supply housing
a ssem b ly .
3. Check for dirt- in lube o il.
Change o il if n e c e ssa r y .
4 . Readjust or rep la ce sw itch.
Check for proper operation
of th rottle and clutch return
sp rin g s.
One or More C ylinders F ail to
Stop Braking or Engine S ta lls.
1. One or m ore sla v e piston
control v a lv e s stuck in "On"
p osition.
2. Solenoid valve exhaust p a s s ­
age plugged.
3. Clutch sw itch stuck in the
"On" position .
4. B uffer sc r e w sw itch se t too
tight.
1. Cheek control valve for bind­
ing, rem ove, clean, and r e ­
p la c e if n e c e ssa r y . Check
lube o il for dirt.
2. Clean o il exhaust port in bot­
tom of supply housing.
3. Check sw itch condition. R e­
p la ce, if n e c e ssa r y .
4. R eposition sw itch and check
sw itch operation.
No Engine Braking.
1. C ircuit breaker opening, or
defective.
2. Low engine o il p r e ssu r e .
3. Sw itches m isadjusted, or de­
fectiv e.
1. Check for sh ort circu it in
w iring h arn ess or solen oid
lea d - rep lace circu it breaker.
2. Minimum o il p r e ssu r e r e ­
quired is 25 p s i.
3. Readjust o r rep lace sw itch es.
Engine M isse s or L o se s P ow er.
1. Slave p iston adjustm ent too
tight.
1. R e set sla v e p iston clea ra n ce
to 0.0 6 6 -in ch a s directed in
text.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCKSHOP MANUAL