Number:__FS-2012-03

Model:

CNG

Date:__November 19, 2012

Approved:
Robert L. Birdwell, Executive Director
Quality Control & Field Service

Subject: Exhaust System Flex Pipe Change

Because the original flex pipe can fail prematurely, we recommend replacing the
flex pipe as soon as possible.

FIELD
SERVICE
BULLETIN

We will be sending you one 01-70763-000, 12" flex pipe to replace the original
flex pipe on each CNG bus you have.
We will also be sending you an Exhaust Bellows Alignment Tube, (Gillig Part
Number 01-71059T000), to ensure the exhaust pipes are properly aligned for this
change.
The procedure to replace this flex pipe and a print of the tool are attached to this
bulletin.
You can file a warranty claim for up to one hour of labor, per bus, to make this
change.
We would like you to fill out the attached form and return to Vy Vu, in Gillig’s
Field Service Department, (Vvu@gillig.com).
We will issue an RGA with the pipes and tool requiring that they be returned to
us in a timely manner.
RLB:rlb
Gillig, LLC
25800 Clawiter Road
Hayward, CA 94545
(800) 735-1500
(510) 785-1500
FAX: (510) 785-1348
BB@Gillig.com

Page 1 of 6

FIELD SERVICE BULLETIN
For replacement of Red Silicone (Linkeo) exhaust bellows with All Metal (Tru-Flex)
exhaust bellows on 2010 Emissions year engine equipped buses
Note: Read entire bulletin before beginning work
Bellows and Alignment Tool Part Numbers:
29' ISL Diesel
35'/40' ISL Diesel
29'/35'/40' ISB Diesel Hybrid
29'/35'/40' ISL-G CNG
All Applications

Bellows P/N
Bellows P/N
Bellows P/N
Bellows P/N
Alignment Tool P/N

01-70942-000 (12.25")
01-70763-000 (12")
01-70763-000 (12")
01-70763-000 (12")
01-71059T000

NOTE: IDENTIFY THE 12.25" ALL METAL BELLOWS FROM THE GILLIG PART NUMBER AND RED DOT
MARKED ON THE BELLOWS. NOT TO BE USED FOR 12” APPLICATIONS.
Background: This bulletin defines how to
replace the red silicone exhaust bellows with
metal bellows. To ensure proper bellows
alignment, the procedure uses an alignment tool
to ensure the correct alignment of the mating
exhaust pipes to the bellows.

Red Silicone Bellows (Linkeo)

All Metal Bellows (Tru-Flex)

V-Band Clamp Installation Procedure:
Bellows replacement and alignment will require removal/installation of V-Band clamps. Use the following
procedure for proper V-Band clamp installation.
Before installing a new clamp or re-using an existing clamp, check for the following. If any of these problems are
found, replace the clamp.
 T-Bolt bent or damaged
 T-Bolt thread damaged or stripped
 T-Bolt nut loose. The T-Bolt nut is a prevailing torque nut and should not turn freely
 Any signs of damage or distortion to the clamp
Installation Notes
 Do not apply anti seize to the T-Bolt, nut or clamping surfaces.
 DO NOT use an air impact wrench to install clamp.
 Recommended installation speed of the T-Bolt nut is 100-200 rpm. Do not exceed 500 rpm.
 Before installing a clamp, make sure the flanges are properly aligned. The clamp should not be required to
force or pull the connection into alignment. A forced connection can result in a leaking joint or premature
failure.
 Cover open pipes to prevent debris entering the turbo or exhaust piping.
V-Band Clamp installation: For use with new clamps and reinstalling used clamps.
1. Make sure the flange and clamping surfaces are clean, dry and free of any contaminants
2. If the flanges are not already assembled, place the clamp over one of the flanges, and then assemble the
flanges.
3. If the flanges are already assembled, open the clamp by removing the nut and remove the bolt from one end
of the clamp. Widen the clamp by hand just enough to allow the clamp to slip over the joint. Be sure to not
over-extend the clamp. Then reassemble the bolt into the clamp and install the nut back onto the T-Bolt.
4. Tighten the clamp to approximately 5-6 ft-lb. While tightening, gently tap around the perimeter of the
clamp to ensure proper seating of the clamp on the flange.

Page 2 of 6
5.
6.
7.

Torque the clamp using a torque wrench to 13+/- 0.5 ft-lb.
Inspect clamp after assembly to ensure proper alignment of the flanges. Verify the two clamp band loops
are not touching.
Once installed and torqued to 13 ft-lb DO NOT re-torque to 13 ft-lb. The clamp design accounts for a drop
in torque of up to 50% after initial engine run. If checked, a torqued clamp on an engine that has been run
should fall between 6 and 13 ft-lb. If torque is below 6 ft-lb, re-torque to 6-7 ft-lb.

Note: Torque Check and Re-torqueing of installed clamps.
 Do not re-torque an installed clamp to 13ft-lb. 13 ft-lb torque is only used when installing a new
clamp or re-installing a used clamp that was removed for servicing. 13ft-lb is used to allow for the
initial seating of the clamp at installation.
 Torque of previously installed clamps to be a minimum of 6 ft-lb. Check torque by setting torque
wrench to 6 ft-lb. If 6 ft-lb is reached without nut movement, torque is correct. If nut moves before
reaching 6 ft-lb, torque nut to 6-7 ft-lb. (Note: An installed clamp is a clamp that was torqued to 13 ftlb at installation and has not been removed or loosened.)
Bellows Replacement and Alignment Procedure:
Note: Settee hatch removal is not required to remove the red silicone bellows and is not required to use the
alignment tool to check the alignment, if the alignment of the exhaust piping is correct per alignment tool, the all
metal bellows can be installed without settee hatch removal. Hatch removal is only required if the adjustment to the
exhaust piping is required.
Before servicing the bus, change the "SELECT IGNITION" switch from "FRONT" to "ENGINE KILL/OFF" in the
rear run box. Make sure that the exhaust bellows is cool enough to work on.
1.

Remove the existing red silicone exhaust bellows from the bus by loosening the two V-Band clamps.
FIGURE 1. ISB DIESEL HYBRID ENGINE

FIGURE 2. ISL DIESEL ENGINE

FIGURE 3. ISL-G CNG ENGINE

LOOSEN V-BAND CLAMPS
SHOWN TO REMOVE THE
EXISTING BELLOWS
(CLAMP LOCATION “C”)

Page 3 of 6

2.

Insert the alignment tool between the turbo outlet pipe & muffler inlet pipe (as shown below), tighten the
bottom V-Band clamp to approximately 6 ft-lb and align the other end of the tool with muffler inlet pipe.
NOTE: DO NOT FORCE THE ALIGNMENT TOOL TO FIT.

MUFFLER
INLET PIPE
TURBO
EXHAUST
OULET PIPE

ALIGNMENT
TOOL
FIGURE 4.

FIGURE 5.
3.

Then tighten the upper V-Band clamp to approximately 6 ft-lb.

FIGURE 6.

TIGHTEN V-BAND
CLAMP

Page 4 of 6
If alignment tool fits between the pipes with V-Band clamps installed to approximately 6 ft-lb, remove the
alignment tool and install new all metal bellows (jump to step 9).
If alignment tool does not fit then continue to step 4.
4.
5.

To access the turbo outlet pipe V-Band clamps, remove the settee hatch from inside the bus.
Loosen both Cummins cast turbo outlet elbow V-Band clamp and exhaust turbo outlet pipe V-Band clamp
through the settee hatch access.

LOOSE V-BAND CLAMPS
THROUGH SETTEE HATCH

FIGURE 7.
VIEW FROM
SETTEE HATCH

FIGURES 8 & 9. ISB DIESEL HYBRID ENGINE SHOWN
CAST ELBOW AT TURBO
OUTLET V-BAND CLAMP
(CLAMP LOCATION “A”)

FIGURE 10 & 11. ISL ENGINE SHOWN

TURBO OUTLET
PIPE INLET
V-BAND CLAMP
(CLAMP
LOCATION “B”)

Page 5 of 6
TURBO OUTLET PIPE
INLET V-BAND CLAMP
(CLAMP LOCATION “B”)

FIGURES 12 & 13. ISL-G CNG ENGINE SHOWN

6.

Loosen the V-Band & U clamps on exhaust muffler inlet pipe. Loosening the clamps will allow the pipes to
move into alignment.

U-CLAMP
(LOCATION “E”)

MUFFLER INLET
V-BAND CLAMP
(CLAMP LOCATION “D”)

FIGURE 14. ISB/ISL DIESEL ENGINE SHOWN

MUFFLER INLET
V-BAND CLAMP
(CLAMP LOCATION “D”)

U-CLAMP
(LOCATION “E”)

FIGURE 15. ISL-G CNG ENGINE SHOWN

EXHAUST MUFFLER
INLET PIPE

EXHAUST MUFFLER
INLET PIPE

Page 6 of 6
7. Align the pipes with alignment tool & torque all clamps to 13+/- 0.5 ft-lb in the following order:


CAST TURBO OUTLET ELBOW V-BAND CLAMP



EXHAUST TURBO OUTLET PIPE V-BAND CLAMP




ALIGNMENT TOOL UPPER & LOWER V-BAND CLAMPS
MUFFLER INLET PIPE V-BAND CLAMP



MUFFLER INLET PIPE U-CLAMP

LOCATION “A”, SEE FIGURES:
8 & 9 FOR ISB on page 4
10 & 11 FOR ISL on page 4
12 & 13 FOR ISL-G on page 5
LOCATION “B”, SEE FIGURES:
8 & 9 FOR ISB on page 4
10 & 11 FOR ISL on page 4
N/A for ISL-G
LOCATION “C”, SEE FIGURE 16 BELOW
LOCATION “D”, SEE FIGURES:
14 FOR ISB on page 5
14 FOR ISL on page 5
15 FOR ISL-G on page 5
LOCATION “E”, SEE FIGURES:
14 FOR ISB on page 5
14 FOR ISL on page 5
15 FOR ISL-G on page 5

Clamp Part Numbers:
Clamp Location
B – Turbo Outlet C – Bellows
Pipe Inlet
Inlet/Outlet
53-28193-003
01-58451-000

Engine Model
ISL Diesel

A – Cast Elbow at
Turbo Outlet
Cummins P/N 102408

ISB Diesel Hybrid

Cummins P/N 102408

53-28193-005

ISL-G CNG

N/A

53-28193-006

D - Muffler
Inlet
53-28193-003

E - U-Clamp
54-00029-002

01-58451-000

53-28193-003

54-00029-002

01-58451-000

53-28193-003

54-00029-002

UPPER V-BAND
CLAMP

LOWER V-BAND
CLAMP

FIGURE 16.

8. After torqueing all the clamps to 13+/- 0.5 ft-lb, remove the alignment tool by loosening upper & lower VBand clamps.
9. Insert new all metal exhaust bellows between the turbo outlet pipe & muffler inlet pipe noting the flow
direction labeled on the bellows, and then torque bellows V-Band clamps to 13+/- 0.5 ft-lb.
10. After completing the installation:
 Confirm the exhaust bellows is not damaged or interfering with surrounding components.
 Start the engine and check for exhaust leaks.
 Reinstall the settee hatch (if removed).

Johnny

01-71059T000_1.DWG ()

ASSEMBLY DETAIL

ISO VIEW

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