INSTRUCTION TO SERVICE
ITS: 6271
SECTION:

231

WRITTEN BY:

Mike Pearson

SUBJECT:

Replace Surge Tank

Cooling System

ITS6271

THIS DOCUMENT AND THE CONTENTS DISCUSSED HEREIN ARE THE CONFIDENTIAL AND PROPRIETARY
INFORMATION OF NEW FLYER INDUSTRIES CANADA ULC AND NEW FLYER OF AMERICA INC. AND ARE
DISCLOSED BY NEW FLYER IN CONFIDENCE. THIS DOCUMENT AND THE CONTENTS HEREIN ARE NOT TO
BE DISCLOSED BY THE INTENDED RECIPIENT WITHOUT THE PRIOR WRITTEN AUTHORIZATION OF NEW
FLYER. ANY UNAUTHOIZED DISCLOSURE, REPRODUCTION OR OTHER DISTRIBUTION OF THIS
DOCUMENT OR INFORMATION IS STRICTLY PROHIBITED AND MAY RESULT IN ACTION BEING TAKEN
AGAINST THE PARTY MAKING THE UNAUTHORIZED DISCLOSURE. THIS DOCUMENT AND ALL COPIES
HEREOF MUST BE RETURNED TO NEW FLYER UPON REQUEST.

PROCEDURE:
1. Turn the main battery disconnect switch to the “OFF” position.
2. Open the engine compartment door.
3. Open the interior engine access door.
4. Open the radiator access door.
5. Isolate the heating system loop from the engine as follows, See Figure 1:
a.

Close the coolant outlet valve, located in coolant line between the engine and the booster pump.

b.

Close heating system return valve, located in heating system return line close to lower radiator tube.

CAUTION:

To avoid personal injury from hot coolant, DO NOT work on the engine if it is hot and
the coolant is steaming. Allow the engine to cool before working on the cooling system.

Valve #1

Valve #2

Figure 1: Booster Pump Lines

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6. Relieve the cooling system pressure by lifting the vent lever on the surge tank pressure relief cap. Remove and
discard the coolant pressure cap once the pressure has been relieved. See Figure 2.

Pressure Relief Valve
Vent Lever, may differ
in appearance

Figure 2: Surge Tank Pressure Relief

NOTE:

If coolant is to be recovered, make sure container is clean and chemical free. If not, used coolant
must be recycled or disposed of in accordance with municipal, state and federal government
regulations.

7. Place a suitable container under the radiator drain cock. Open the drain cock and drain engine coolant until level is
below the surge tank drop tube then close the drain cock. See Figure 3.

Open the drain cock and
drain engine coolant

Figure 3: Drain Engine Coolant

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Surge Tank Removal
8. Disconnect and tie back the existing coolant hose from the surge tank radiator cap filler neck, discard the existing
hose clamp. See Figure 4.

Remove and discard
the existing surge tank
pressure release cap

Disconnect and tie back
the coolant hose

Figure 4: Surge Tank Coolant Hose Removal
9. Disconnect and tie back the existing low coolant sensor harnesses. See Figure 5.
10. Disconnect, tag and tie back all remaining coolant hoses to the surge. See Figure 5.
Remove and tie back
the existing coolant
hose to the rear of
the radiator

Existing Coolant
Surge Tank

Remove and tie back
the existing coolant
hose to the EGR
cooler
Remove and tie back
the existing coolant
hose to the EGR
cooler

Disconnect and tie
back the existing low
coolant sensor
harness

Disconnect and tie
back the existing low
coolant sensor
harness

Figure 5: Remove Surge Tank Hose Assemblies

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11. Remove and save the existing HVAC B-pump coolant lines that run underneath the surge tank as well as the
existing hose connections, clamps and hardware for reuse later in this install. See Figure 6.

Remove and save
existing hose clamps
and connections

Existing Coolant
Surge Tank

Remove existing
HVAC B-pump
coolant lines
Remove and save
existing hose clamps
and connections

Remove and save
existing mounting
clamps and hardware
Figure 6: HVAC B-pump Coolant Line Removal
12. Remove and save the existing surge tank drop tube as well as the existing hose connections, clamps and hardware
for reuse later in this install. See Figure 7.

Remove and save
existing hose clamps
and connections

Remove and save
existing surge tank
drop tube

Remove and save
existing hose clamps
and connections

Figure 7: Surge Tank Drop Tube Removal

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13. Remove the mounting hardware securing the surge tank mounting flanges to the vehicle structure and set aside
for reuse later in this install. Remove surge tank. See Figure 8.
Remove and save
the existing surge
tank mounting
hardware

Figure 8: Remove Surge Tank Mounting Hardware

Surge Tank Assembly
14. Place new surge tank p/n 634511 on a clean bench and ensuring the tank is free from debris or contaminants
assemble as follows:
a.

Install bushing p/n 5952466 into surge tank center ¾” MPT port as per Step 19. See Figure 9.

b.

Install adapter p/n 494795 (x3) into newly installed bushing from Step 14a and open ½” FPT ports (x2) as
per Step 19. See Figure 9.

c.

Install Low coolant sensor p/n 610634 into the lower M20 port. Torque sensor to 14-16 ft*lbs dry, orientation
is not important. See Figure 9.

d.

Install adapter p/n 634366 into the upper M20 port as per Step 19. See Figure 9.

e.

Install low coolant sensor p/n 460722 into newly installed adapter from Step 14d. Torque sensor to 26 in*lbs
dry. DO NOT USE LOCTITE. Continue rotating as needed until 3 pin connector terminals are vertical. See
Figure 9.
Install adapter p/n 494795
Install bushing p/n
5952466 into surge tank
center ¾” MPT port

Install low coolant
sensor p/n 460722

Install adapter p/n
634366 into the
upper M20 port

Install Low coolant
sensor p/n 610634 into
the lower M20 port

New surge tank
p/n 634511
Figure 9: Partial Surge Tank Assembly

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f.

Install ¼” plug p/n G127951 and ¾” plug p/n G127952 into corresponding ports on the top of the surge tank
as per Step 19. See Figure 10.

g.

Install bushing p/n 5959829, 45° elbow p/n 5955052 and shrader valve p/n 5956167 into the side port of the
surge tank as per Step 19. The shrader valve is to face down as shown in Figure 10.

h.

Install the fluid level gauge p/n 411110 into the bottom front surge tank port as per Step 19. See Figure 10.

i.

Install radiator cap p/n 470238.
Install ¾” plug p/n G127952

See Figures 11 & 12

Install ¼” plug p/n G127951
Install bushing p/n 5959829,
45° elbow p/n 5955052 and
shrader valve p/n 5956167

Install the fluid gauge
p/n 411110
New surge tank
p/n 634511

Install radiator cap p/n 470238
Figure 10: Partial Surge Tank Assembly
15. Install new 90° elbows p/n 216632 (x2) into the threaded surge tank port and gauge installed in Step 14h as per
Step 19. Locate and orient as shown in Figure 11.
Top of surge tank
looking down

Orient new 90°
elbow p/n 216632
as shown

Streetside

Existing surge
tank assembly

Orient new 90°
elbow p/n 216632
as shown
Figure 11: Surge Tank Fitting Installation

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16. Install approx. 13” of hose p/n 376677 between the barbed elbows installed in Step 15 and secure using clamp
p/n 131322 (x2). See Figure 12.
17. Loosely install bracket assembly p/n 498573 to the underside of the existing mounting plate on the surge tank
using bolt p/n 10B04012, washer p/n 10W04000 (x2) and nut p/n 40N04000. See Figure 12.
18. Secure the top of the coolant level gauge installed in Step 14h to the surge tank bracket installed in Step 17 using
p-clip p/n 092585 and screw p/n 14S00008. See Figure 12.

Bolt p/n 10B04012

Install approx. 13” of
hose p/n 376677

Washer p/n 10W04000
Clamp p/n 131322

Clamp p/n 131322
Elbow p/n 216632

Elbow p/n 216632

P-clip p/n 092585
Screw p/n 14S00008
Washer p/n 10W04000
Coolant level gauge
p/n 411110

Nut p/n 40N04000
Figure 12: Surge Tank Coolant Gauge Installation

19. Fitting installation:
a.

Inspect the threads to be sure they are not damaged or contain slivers, burrs, dirt or other contaminants.

b.

Apply thread sealant p/n 8110442 evenly, without air pockets, around the circumference of the thread,
leaving the first ½ to 1 ½ threads unpasted and extend to completely cover a minimum of the next three
threads. Ensure that orifices remain unblocked. Note: Threads supplied with Vibra-Seal coating (red dry
seal) do not require additional thread sealant.

c.

Install the fitting finger tight.

d.

Apply two full turns past finger-tight.

Surge Tank Assembly
20. Ensuring the newly assembled tank is free from debris or contaminants install using the hardware removed in
Step 13 align tank mounting flange holes with the existing weld nuts in the bus structure, reference Figure 8.
21. Re-connect the upper surge tank low coolant warning sensor electrical connection removed in Step 9. Reference
Figure 5.
22. On the existing low coolant engine derate sensor (bottom sensor) harness cut off the existing 3 circuit tower as
close as possible to the connector of the disconnected harness and terminate each wire with the supplied terminal
(NF P/N 198432).