(a)
Every motor vehicle having a device (other than as part of its cargo) capable
of expelling harmful combustion fumes shall have a system to direct the
discharge of such fumes. No part shall be located where its location would
likely result in burning, charring, or damaging the electrical wiring, the fuel
supply, or any combustible part of the motor vehicle.
(b)
No exhaust system shall discharge to the atmosphere at a location immediately
below the fuel tank or the fuel tank filler pipe.
(c)
The exhaust system of a bus powered by a gasoline engine shall discharge to the
atmosphere at or within 6 inches forward of the rearmost part of the bus.
(d)
The exhaust system of a bus using fuels other than gasoline shall discharge to
the atmosphere either:
(d)(1) At or within 15 inches forward of the rearmost part of the
vehicle; or
(d)(2) To the rear of all doors or windows designed to be open, except
windows designed to be opened solely as emergency exits.
(e)
The exhaust system of every truck and truck tractor shall discharge to the
atmosphere at a location to the rear of the cab or, if the exhaust projects
above the cab, at a location near the rear of the cab.
(f)
No part of the exhaust system shall be temporarily repaired with wrap or
patches.
(g)
No part of the exhaust system shall leak or discharge at a point forward of or
directly below the driver/sleeper compartment. The exhaust outlet may discharge
above the cab/sleeper roofline.
(h)
The exhaust system must be securely fastened to the vehicle.
(i)
Exhaust systems may use hangers which permit required movement due to expansion
and contraction caused by heat of the exhaust and relative motion between
engine and chassis of a vehicle.
[53 FR 49401, Dec. 7,
1988].