McNeilus FEL Tailgate CNG System
Cylinder Neck Mount Inspection
ENP-732
February 17, 2020
Copyright ©2020. Agility® Fuel Solutions. All Rights Reserved.

Table of Contents
1. Introduction ............................................................................................................................... 3
1.1. Warning Statements Used in this Bulletin .............................................................................. 3
2. Affected Vehicles ....................................................................................................................... 4
3. Tools and Materials ................................................................................................................... 4
4. Cylinder Neck Mount and Bushing Inspection .......................................................................... 5
4.1. Inspection Procedure ............................................................................................................. 5
4.2. Failed Cylinder Neck Mounts and Bushings – PRD End ....................................................... 6
4.3. Failed Cylinder Neck Mounts and Bushings – Valve End ...................................................... 6
5. Warranty Information................................................................................................................. 7
6. Support, Service or Parts .......................................................................................................... 7
7. Proprietary Statement ............................................................................................................... 8
8. Trademark Notice ...................................................................................................................... 8

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1. Introduction
Unexpected wear on cylinder neck mounting blocks has been found on certain Agility® Fuel
Solutions (Agility®) tailgate compressed natural gas (CNG) systems supplied to McNeilus for use
on front end load (FEL) refuse vehicles.
Neck blocks have been found to become “egg shaped” with excessive clearance at the top of
the cylinder neck boss and neck blocks. Initial observations show that the non-valve end neck
block and/or bushing may be wearing out first, causing the stationary valve-end neck block to
wear from excessive movement of the cylinder. The neck block secures the valve end of the
cylinder to the fuel system structure and the non-valve end of the cylinder has a bushing that
allows the cylinder to extend and retract in length from the pressure changes in the cylinder.
Agility® is conducting a failure analysis on the parts removed from units discovered in the field
and instrumenting multiple vehicles with accelerometers for in-use data collection.
This document is intended as a supplemental aid to regularly scheduled CNG system
inspections to highlight an area where wear can occur. Inspections shall be done as a part of
regularly scheduled CNG systems inspections.
Agility® urges McNeilus FEL fleet operators to perform CNG system inspections and
maintenance at the regularly recommended intervals.

1.1. Warning Statements Used in this Bulletin
Personal injury or death may occur if procedures are not followed.

Damage to equipment, fuel system or vehicle is possible if instructions are not followed.

Best practices or hints to help an operation or procedure go smoothly.

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2. Affected Vehicles
All McNeilus FEL vehicles equipped with Agility® tailgate mount CNG fuel systems.

1

2

Figure 1. McNeilus FEL refuse vehicle equipped with Agility® tailgate mount CNG fuel
system: driver side (1), passenger side (2).

3. Tools and Materials
Use the following basic tools and supplies to properly inspect neck mounts and bushings:
Item
spray bottle

Function

mild soap and water
soft bristle brush

Clean debris from cylinder neck mounts
and bushing mating surfaces

shop rags
Feeler gauge

ENP-732

Measure bushing to neck mount gap

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4. Cylinder Neck Mount and Bushing Inspection
Agility® CNG fuel systems using sliding block cylinder neck mounts must be checked visually for
Delrin bushing wear and threaded block wear at regular intervals to prevent cylinder damage.
Figure 2

1
Figure 2. Cylinder (1), sliding block cylinder PRD end mount (circled).
Additionally, a more detailed physical measurement of sliding block bushing gaps should be
performed at the following intervals to confirm evidence of excessive movement or play:
Duty Cycle

Frequency

Severe Duty

Every 15000 mi.
(24140km) /
1000 hours

Normal Duty

Every 75000 mi.
(120700km) /
3000 hours

If gaps greater than 1/16-in. (1.6mm) between the cylinder neck and threaded block or Delrin
bushing are present, examine the cylinder necks for wear, and replace worn neck blocks and/or
bushings.

4.1. Inspection Procedure
Use the following inspection procedure to check bushing and threaded block gaps:
1. Clean debris from neck mounts, bushings and threaded blocks with mild soap and water; if
required: use a soft bristled brush.
2. Use a feeler gauge to measure the gap between bushing and neck mounting blocks.
3. If neck mount bushings are found with gaps exceeding specification or cylinder neck mounts
are damaged, contact Agility® to schedule repair/replacement of failed/worn components.

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4.2. Failed Cylinder Neck Mounts and Bushings – PRD End
Cylinder neck block bushing failures have been found in the “slip side” or sliding block end of
the cylinder where the pressure relief device (PRD) is installed. Bushing wear has been
evidenced by a visible gap. Figure 3

2

3
1

Figure 3. Sliding block end of cylinder: PRD plug (1), bushing (2), cylinder neck block
(3). Gap (arrow) exceeds allowed tolerance stated in Section 4, and bushing must be
replaced.
In some instances, bushing failure also led to failure of the sliding mount neck mount assembly.

4.3. Failed Cylinder Neck Mounts and Bushings – Valve End
Cylinder neck block bushing failures have also been found in the “fixed side” or non-sliding
threaded block end of the cylinder where the cylinder shut off valve is installed. Bushing wear
has been evidenced by a visible gap. Figures 4 and 5

2
3
1

Figure 4. Fixed block end of cylinder: shut off valve (1), bushing (2), cylinder neck block
(3). Gap (arrow) exceeds allowed tolerance stated in Section 4 and bushing must be
replaced.

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Figure 5. Cylinder fixed block end detail: shut off valve (1), bushing (2), cylinder neck
block (3). Gap (arrow) exceeds allowed tolerance and bushing must be replaced.
In some instances, bushing failure also led to failure of the fixed threaded block neck mount
assembly.

5. Warranty Information
This inspection procedure is part of normal scheduled maintenance and not subject to warranty
coverage.

6. Support, Service or Parts
Fuel system in- or out- of warranty product support may be obtained by calling Agility Fuel
Solutions Customer Care or via email.

Customer Care
+1 855 500 2445 (toll-free, U.S. and Canada)
+1 949 267-7745
Support
[email protected]
Parts Orders
[email protected]
When calling or emailing, please provide your name, phone number, email address, and
complete vehicle information: VIN, year, make, model, mileage, unit number vehicle owner, and
current vehicle location. A service advisor will contact you to arrange vehicle repair or ship a part.

Agility Fuel Solutions
3335 Susan Street, Suite 100
Costa Mesa, CA 92626
www.agilityfuelsolutions.com

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A. All replacement parts must adhere to standards and ratings specified by Agility®.
Using any part not approved by Agility® is not recommended and may compromise
the integrity and safety of the system.
B. Do not remove components from original packaging until necessary. Any
components to be reinstalled must be thoroughly cleaned, inspected and stored in a
satisfactory manner until reinstallation.

7. Proprietary Statement
The information provided within this document is proprietary and confidential. All prior versions,
including updates and revisions forwarded separately, are proprietary. The information provided
by Agility® to its customers and clients is solely for the use of those customers and clients. No
portion of this publication may be reproduced or distributed without express written consent of
Agility®. Agility® reserves the right to utilize the intellectual property contained within this
publication as content for any other publication produced by Agility®.

8. Trademark Notice
Agility® is a registered trademark of Agility® Fuel Solutions. Trademarks of other manufacturers
are the property of their respective companies.

Revision
--

ENP-732

Description
Initial Release

Author

Approved By

Date

C.Grasso

Management Team

2/17//2020

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