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35–03 Axle Lubricant Changing

and Magnetic Plug
Cleaning

A regular schedule for changing the axle lubricant in
a particular vehicle and operation can be accurately
determined by analyzing oil samples taken from the
axle at specified intervals or mileages. Lubricant sup-
pliers frequently make their laboratory facilities avail-
able for determining the useful life of their product
under actual service conditions. The final schedule
that is recommended may, for economic reasons, be
related to lubricant changes that are governed by
climatic conditions and magnetic plug maintenance.
Change lubricant type and viscosity as climatic tem-
peratures demand, regardless of vehicle mileage or
established change schedule.

The normal operating temperature of compounded
lubricants during the summer season is about 160 to
220°F (71 to 104°C). The chemicals and additives
that give these lubricants increased load carrying ca-
pacity oxidize faster at temperatures above 220°F
(104°C), contributing to more rapid lubricant deterio-
ration. For this reason, lubricants of this type that
operate continuously at high temperatures must be
changed more frequently.

NOTICE

Failure to change the axle lubricant at more fre-
quent intervals, when adverse operating condi-
tions require, could result in axle damage.

Axle Draining

Park the vehicle on a level surface, shut down
the engine, and set the parking brake. Chock the
tires.

Clean the fill plug and the area around it. Re-
move the plug from the oil fill hole. See

Fig. 1

for

a Detroit axle or

Fig. 2

for a Meritor axle.

CAUTION

Be careful when draining the axle oil. It may be
very hot, and could cause personal injury if it con-
tacts the skin.

Remove the plug at the bottom of the housing
and drain the lubricant while the unit is warm.

Allow enough time for all the old lubricant to
drain completely.

Clean the drain plug. For magnetic drain plugs, a
piece of key stock or any other convenient steel
slug may be used to short the two magnetic
poles and divert the magnetic field.

NOTE: Meritor recommends using magnetic
plugs with elements having a minimum pickup
capacity of two pounds (one kilogram) of low-
carbon steel in plate or bar form. Magnets will
rapidly lose effectiveness as collected material
bridges the gap between the two poles. Clean
or change the plugs before this occurs. It may
be necessary to clean or change the plugs one
or more times between lubrication change inter-
vals.

After cleaning the drain plug, install and tighten
the plug 30 lbf·ft (41 N·m) for Detroit axles or 35
lbf·ft (47 N·m) for Meritor axles.

Axle Filling

With the vehicle on a level surface, fill the axle
housings to the bottom of the oil fill hole (in the
carrier or housing) with recommended lubricant;
see

Table 2

. Refer to

Table 3

for Detroit drive

axle lubricant capacities or

Table 4

for Meritor

drive axle lubricant capacities.

NOTE: Some Meritor axles have a small tapped
and plugged hole located below the housing oil
fill hole. This smaller hole is for the lubricant
temperature sensor only and must not be used
as a fill or level hole.

Install the fill hole plug and tighten it 30 lbf·ft (41
N·m) for Detroit axles or 35 lbf·ft (47 N·m) for
Meritor axles.

After filling the carrier and housing assembly with
lubricant, drive the vehicle unloaded for one or
two miles (two or three kilometers) at speeds not
to exceed 25 mph (40 km/h) to thoroughly circu-
late the lubricant throughout the assembly.

Detroit Drive Axle Lubricant Capacities

Axle Model

Capacity

†

: pints (L)

ARS–13.0–2

15 (7)

Rear Axle

Saf-T-Liner C2 School Bus Maintenance Manual, June 2015

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