Code of Maryland Regulations › Title 11 - DEPARTMENT OF TRANSPORTATION › Subtitle 14 - MOTOR VEHICLE ADMINISTRATION-VEHICLE INSPECTIONS › Chapter 11.14.04 - Safety Standards for Trucks, Truck Tractors, Commercial Buses, and Type I School Vehicles › Section 11.14.04.06 - Exhaust System

Current through Register Vol. 51, No. 14, July 12, 2024
A. The exhaust
				system includes the exhaust manifold, and all piping leading to and including
				the muffler, catalytic converter, resonator, and the tail piping.
Procedures:
Reject Vehicle If:
(1) With engine running and the vehicle on a hoist, lift,
						  or over a pit, visually inspect the exhaust pipes, mufflers, resonators, and
						  tail pipes for leaks, deterioration, proper mounting, damage and general
						  condition. (a) Rusted or corroded areas shall be given particular attention.
						  (b) Holes in the system made by the manufacturer for drainage are not cause for
						  rejection.
(1) Vehicle has no muffler. (2) There are loose or
						  leaking seams or joints. (3) There are holes caused by corrosion or temporary
						  repairs made to the exhaust pipe, muffler, resonator, or the tail pipe. Welding
						  or brazing is considered a permanent repair if it does not leak. (4) Tail pipe
						  end is pinched or obstructed or does not extend beyond the passenger or driver
						  area.
(2) The tail pipe shall extend beyond the passenger or
						  occupant compartment and the enclosed cargo area if it is open to the driver or
						  passenger area.
(5) The system is not properly mounted, or securely
						  fastened, or if the seam of a muffler or resonator in a school vehicle faces
						  the fuel tank, fuel lines, or floor of the vehicle.
(3) Type I school buses shall have a full length tail
						  pipe extending beyond the rear wheels and exiting beyond the side or rear of
						  the body unless the vehicle is equipped with a left side exhaust system which
						  meets the following criteria: (a) The exhaust pipe may not pass within 12
						  inches of the gasoline tank or its connections unless a suitable baffle is
						  installed between the exhaust system and these components. On vehicles with
						  left side mounted gasoline tanks, compliance with this requirement may be more
						  difficult; however, this requirement shall still be met.
(6) There are loose muffler baffles; the vehicle is
						  equipped with cut-out or similar device; or the system is not original or
						  equivalent. (7) Any part of the system passes through the occupant compartment,
						  or there are any leaks in the heat exchange boxes or ducts of vehicle using
						  engine exhaust heat to warm the interior of the vehicle.
(b) No part of the exhaust system may pass within 12
						  inches of any flexible brake hose or vacuum booster unless a suitable baffle is
						  installed between the exhaust system and these components.
(8) The tail pipe does not extend beyond the occupant
						  compartment and the enclosed cargo area if it is open or the occupant
						  compartment.
(c) The exhaust pipe should be at approximately a
						  45-degree angle as it approaches the left body line to prevent back pressure
						  and heat buildup. (d) The exhaust pipe shall be deflected downward as it
						  approaches the left side of the body.
(9) On a school vehicle, the system passes directly under
						  the emergency door, there is a reduction in size of tail pipe after it leaves
						  muffler, or system does not extend to outside, not more than 1/4 inch beyond
						  the rear bumper as originally designed.
(e) The exhaust pipe shall exit behind the driver's
						  compartment.
(10) Exhaust pipe, muffler, or tail pipe is not leak
						  proof construction. Flexible pipe that does not leak is acceptable, except on
						  school vehicles.
(11) It emits continuous exhaust fumes or smoke which
						  obscures persons or objects from view.
(12) On a school vehicle, the system passes directly
						  under the emergency door, or there is any reduction in size of the tail pipe
						  after it leaves the muffler.
(13) Type I school vehicle with left side exhaust does
						  not meet the requirements established.