Hub Cap, Leaking
V-773-005A
(March 2023)

Valid for
All Volvo model trucks built from June 29,2020 to current.

Case description
Volvo trucks require a visual inspection of the steer axle hub caps during regular maintenance schedules. During a visual inspection it can be very difficult to
determine if a steer axle hub cap is leaking or seeping and can result in unnecessary warranty claims. Use this document to help determine if a suspected hub
cap is considered a warrantable repair or not.

Inspection Procedure
1. Park the vehicle on a level surface.
2. Apply the parking brake.
3. Place the transmission in neutral.
4. Install the wheel chocks.

5. Disconnect the cable from the negative terminal.

6. Visually inspect the steer axle hub caps for leaks using the chart below to determine if the leak is considered a valid warrantable repair.

Not Accepted as Warranty Failure
Symptom:

Light Purging

Medium Purging

Heavy Purging

Cause:

Light film on the edge of the vent plug

Medium film on the edge and outboard face
of the vent plug

Heavy film on the edge and outboard face of
the vent plug

Hub caps
must vent
due to
buildup of
pressure.
There are
design
features built
into the cap
that
minimizes oil
purging. A
minimal
amount of
purging can
be expected
after periods
of higher
heat.

NO action required Do Not remove.
NO action required Do Not remove.

NO action required Do Not remove.

Purging of oil
through the
hub cap vent
plug.
Appearance
may be
deceptive.

Note:
The
inspection
must not be
conducted
after driving
in wet
weather or a
vehicle wash.
Vent plug
needs to be
free from
water.
Inspection:
Finger test

Warning
Allow the
hub cap
and vent
plug to cool
after
operation.
The vent
plug may
be hot to
the touch
and cause
personal
injury.
Touch the film
with a dry
finger. If the
finger
remains dry,
the vent plug
is not leaking.
If in doubt,
check again
in a few days.
Accepted as Warranty Failure
Symptom:

Leaking

Leakage Excessive oil around the hub cap vent plug
and surrounding areas including the hub itself. Gummy
oil around the vent plug purge point. Oil splatter on the
wheel.
Cause:

Oil buildup on surrounding components

Damaged hub cap and / or vent plug.
Note:
The inspection must not be conducted after driving in
wet weather or a vehicle wash. Vent plug needs to be
free from water.
Inspection:
Finger test

Warning
Allow the hub cap and vent plug to cool after
operation. The vent plug may be hot to the touch
and cause personal injury.
Touch the film with a dry finger. If the finger feels wet,
the vent plug is leaking.

ACTION:
Disassemble wheel end and inspect oil quality, hubs and
bearings. It is recommended to replace the hub
assembly in addition to the hub cap and vent plug as
lack of sufficient oil can lead to damaged bearings.

7. Connect the cable to the negative terminal.

8. Remove the wheel chocks.

Action Required Replace damaged components.

9. Release the vehicle back into service.

Warranty Information
Reimbursement
This repair may be eligible for reimbursement
if a product failure was experienced within
time and mileage limits of the applicable
Warranty coverage. Reimbursement is
obtained via the normal claim handling
process.
Claim Type (used only when uploading from
the Dealer Bus. Sys.)

UCHP
Reimbursement

W

Labor Code
Hub cap seal, replacement
Causal Part

Issued by
Technical Service

7731-03-02-08

24057915