SERVICE MANUAL BULLETIN
This Service Manual Bulletin is prepared by the Publications Department of New Flyer Industries
Canada ULC. Refer to details below.

SMB-170
ISSUE DATE: June 28 2017

APPLICABILITY
VEHICLELENGTH

 30ft.

 35ft.

 40ft.

 60ft.

 Xcelsior®

 MiDi®

 Invero®

 Low Floor

 High Floor

 Diesel

 Diesel/Electric

 CNG

 Fuel Cell

 Trolley/Electric

 Battery/Electric

 ALL
 ALL

VEHICLE TYPE
 LNG

 ALL

FUEL TYPE
SUBJECT

DEF Tank Suction Filter

SECTION TITLE

PM - PREVENTIVE MAINTENANCE

DETAILS

This Bulletin provides corrected information on the replacement of the DEF
tank suction filter on your New Flyer Vehicle.
This information supersedes any prior information on this subject already
provided in your New Flyer Service Manuals. Make this Service Bulletin
available to service personnel to inform them of changed information.

SMB-170

The New Flyer vehicles described in this manual may be protected by one or more
patents and design applications or registrations in the United States and Canada,
and in other countries. Refer to “Vehicle Patent Information” in this manual.
Copyright © 2017 New Flyer Industries Canada ULC

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SERVICE MANUAL BULLETIN
SMB-170
1.

DEF Tank Suction Filter

☞NOTE:

The DEF tank filter replacement interval
will be dependent on operating and environmental conditions. Manually filling the
tank through the filler cap offers potential
for entry of contaminants. Adjust to a more
frequent replacement interval if suction filter appears dirty or has an accumulation of
DEF crystals.
Replace the DEF tank inlet filter every
200,000 miles (321,000 km) or 6,500 operating hours, whichever occurs first, as follows:

4. Remove the two T25 Torx screws securing
the retaining ring to the tank and remove
the retaining ring.

DO NOT pull on wiring harnesses or fittings when trying to remove filter head
from tank.
5. Use a flat head screwdriver to gently pry
under the head unit while simultaneously
pulling on the top of the unit. Continue prying and pulling until the mounting base is
free from the tank.

☞NOTE:

The multi-function head unit assembly
(MFHU) must be removed from the DEF
tank in order to replace the inlet filter.

1.1.

MFHU Removal
1. Set the Battery Disconnect switch to the
OFF position.
2. Disconnect the electrical connectors, coolant lines, and DEF fluid lines from the
multi-function head unit assembly of the
DEF tank. See “Fig. PM-1: DEF Tank
MFHU” on page 3.

DO NOT pull directly upward on MFHU
when removing it from the tank as this
might damage the head unit and seal
bore. ALWAYS angle the unit out of the
tank to prevent damage.
6. Pull the MFHU upward until the foot of the
sensor unit approaches the opening in the
tank. Rotate the MFHU and angle the heel
of the sensor foot upwards into the tank
bore. Carefully lift the MFHU until completely free of the tank bore.

3. Mark the position of the MFHU relative to
the DEF tank.

2 of 4

The New Flyer vehicles described in this manual may be protected by one or more
patents and design applications or registrations in the United States and Canada,
and in other countries. Refer to “Vehicle Patent Information” in this manual.
Copyright © 2017 New Flyer Industries Canada ULC

SMB-170

SERVICE MANUAL BULLETIN
SMB-170

s0700423a.svg

Fig. PM-1: DEF Tank MFHU

1.2.

Suction Filter Replacement
1. Remove the filter retention screw located
on the bottom of the filter. Discard the
screw. See “Fig. PM-2: Suction Filter” on
page 4.
2. Remove and discard the upper and lower
filter mounting brackets.
3. Pull the filter off the suction tube and discard the filter.

☞NOTE:

Examine the filter and if extremely dirty or
contaminated, it is recommended that the
tank be cleaned internally.

4. Insert the new upper filter bracket through
the gap between the heater tubes and the
bottom of the sensor.
5. Position the new lower filter bracket at the
bottom of the heater tube and hold parallel
with the upper filter bracket.
6. Position the suction tube housing of the
new filter onto the bottom of the suction
tube and press the filter upward toward the
bottom of the sensor foot. Ensure the suction tube is fully engaged within the tube
housing of the filter.
7. Align the upper and lower filter brackets so
that the filter retention screw can thread
into the upper bracket.
8. Install a new retention screw and torque to
14 to 18 in-lbs.

SMB-170

The New Flyer vehicles described in this manual may be protected by one or more
patents and design applications or registrations in the United States and Canada,
and in other countries. Refer to “Vehicle Patent Information” in this manual.
Copyright © 2017 New Flyer Industries Canada ULC

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SERVICE MANUAL BULLETIN
SMB-170

DO NOT push the MFHU directly into
the tank as this could damage the unit
or the tank bore.
2. Tilt the MFHU to approximately 45° with
respect to the tank bore. Place the toe of
the sensor foot into the bore. Carefully
work the unit through the bore until the bottom of the unit and filter are inside the
tank.

DO NOT press directly on the fittings
when installing the MFHU into the tank.
3. Position the MFHU as marked during
removal and press the on the top of the
blue mounting base until completely
seated in the tank bore.
s0700424a.svg

Fig. PM-2: Suction Filter

1.3.

MFHU Installation
1. Apply a thin layer of O-ring lubricant to the
bore seal O-ring and install on the MFHU
mounting base. Use only DOW UCON LB625 lubricant or Shaw approved equivalent.

☞NOTE:

The lugs on the MFHU mounting base
should align with the cut out/recess on the
tank bore.
4. Replace the retaining ring on the head unit
and install the two T25 Torx screws.
Torque the screws 20 to 30 in-lbs.
5. Reconnect the electrical connectors, coolant lines, and DEF fluid lines to the MFHU.
6. Reset Battery Disconnect switch to ON
position.
7. Start engine and check for coolant or DEF
line leaks.

4 of 4

The New Flyer vehicles described in this manual may be protected by one or more
patents and design applications or registrations in the United States and Canada,
and in other countries. Refer to “Vehicle Patent Information” in this manual.
Copyright © 2017 New Flyer Industries Canada ULC

SMB-170