Exhaust System; Description; Maintenance - GMC 1976 ZEO 6083 Maintenance Manual

EXHAUST SYSTEM
DESCRIPTION
The exhaust system on the models 23' and 26' are
essentially identical except for a longer length tail
pipe on the 26' model. The exhaust manifolds empty
into a muffler for each bank of cylinders which are
Y'ed as shown in Figure 8. The tail pipe continues
to rear of the vehicle . All exhaust system connections
are of the split joint coupled design, secured with
U-Bolt clamps .
MAINTENANCE
EXHAUST RESTRICTION AND LEAKS
Exhaust system should be inspected periodically
for restrictions and leaks. Restrictions such as
kinked or crimped pipes result in excessive back
pressure which can lead to increased fuel consump-
tion, power loss, and possible damage to engine com-
bustion chamber components . Exhaust leaks are
commonly the result of loose clamp assemblies, de-
fective exhaust pipe to manifold packing, or cor-
roded pipes. In addition to objectionable noise, a
leaking exhaust system could allow toxic gases to
enter vehicle.
Damaged or corroded exhaust system compo-
nents should be replaced without delay. If it is abso-
lutely necessary to operate vehicle when an exhaust
leak exists, use extreme caution and keep vehicle well
ventilated .
EXHAUST SYSTEM ALIGNMENT
During installation of a new exhaust pipe, muf-
fler or tail pipe, care should be taken to properly
position components in relation to each other.
On all joints except exhaust manifold, apply
sealer (GM 9985020) or equivalent, to prevent possi-
ble leaks.
FUEL TANK AND EXHAUST 8- 9
On all exhaust and tail pipe clamp
installations locate centerline of clamp
to end of slot in pipe as shown .
CENTERLINE
OF CLAMP
A-1838
Figure 8-Exhaust System and Clamps
Incorrectly assembled parts of exhaust system
are frequently the cause of annoying noises and rat-
tles due to improper clearances . Exhaust compo
nents must have 3/4" clearance from floor to avoid
possible overheating. Therefore, leave all clamp as-
semblies and muffler strap bolts loose temporarily
until the entire system has been inspected to deter-
mine if there is adequate clearance between exhaust
components and frame members . The weight of the
exhaust system should be properly distributed on all
supporting brackets and hangers. If the load is not
properly balanced, reposition pipes at connecting
joints to relieve any concentrated loads. After adjust-
ing hangers, aligning pipes, and repositioning muf-
fler, check entire system for adequate clearance and
then tighten all clamps ; working from front to rear.
(See figure 9) Start engine and inspect all connections
for leakage.
NOTE: When installing exhaust pipe to mani-
fold, always use new packing.