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

SMB-159
ISSUE DATE: July 4 2016

APPLICABILITY
VEHICLE LENGTH

 30ft.

 35ft.

 40ft.

 60ft.

 Xcelsior®

 MiDi®

 Invero®

 Low Floor

 High Floor

 Diesel

 Diesel/Electric

 CNG

 Fuel Cell

 Trolley/Electric

 Battery/Electric

 ALL

VEHICLE TYPE

FUEL TYPE

 ALL

 LNG
 ALL

SUBJECT

Cooling System Pressure & Leak Test

SECTION TITLE

6 - COOLING SYSTEM

DETAILS

This bulletin provides a procedure for testing the cooling system for
leaks 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-159

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 © 2016 New Flyer Industries Canada ULC

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SERVICE MANUAL BULLETIN
SMB-159
1.

Cooling System Pressure &
Leak Test

1.1.

Pressure Test Specifications

PRESSURE TEST SPECIFICATIONS
Item

1.2.

Specification

1

Minimum stabilized pressure

2

Stabilized pressure range after
vehicle operation

Description

16 psi System

18 psi System

14 psi

15 psi

12 to 14 psi

15 to 20 psi

to 50 psi rating. See “Fig. 1: Pressure Test
Tool” on page 2. The pressure/leak test
procedures are described as follows:

☞NOTE:

This test is applicable to cooling systems
using a 16 or 18 psig pressure cap.

❒ Pressure Test Tool Setup

Pressure testing the engine cooling and
HVAC Systems ensures that the vehicle is
free of leaks and is holding pressure for
optimal performance. A pressure test tool
is required with a pressure regulator of a 0

❒ Leak Test Cooling System: After Filling

❒ Leak Test Cooling System: Before Filling
❒ Leak Test Cooling System: After Road Test

s106302a.svg

Fig. 1: Pressure Test Tool

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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 © 2016 New Flyer Industries Canada ULC

SMB-159

SERVICE MANUAL BULLETIN
SMB-159
1.2.1.

Pressure Test Tool Setup

The cooling system is under pressure
and contains hot fluids that can spill or
spray and cause serious scalding injuries. Allow an appropriate amount of
time for the cooling system to cool
down below 120°F (49°C) before working on the cooling system unless otherwise noted.
1. Remove the cap on the Schrader valve.
2. Connect the charging chuck (FTP Connector) of the pressure test tool to the
Schrader valve.
3. Close the mini shutoff valve of the pressure test tool.
4. Ensure that the pressure relief cap is
installed, fully seated and that the relief
valve is closed.
5. Remove the filler cap from the coolant
recovery tank.
6. Ensure that all manual valves in the
booster pump lines, coolant lines, and
HVAC lines are set to the OPEN position.

damage can occur. Adjust the pressure
regulator accordingly before opening
the pressure test tool shutoff valve.
1. Open the 1/4 turn valve, press and hold
the button on the pressure test tool to pressurize the system.
2. Allow the pressure to build above the rating
of the pressure control cap and then
release the button.

☞NOTE:

The pressure relief cap relieves excess
pressure and then the pressure holds.
3. Observe the pressure reading on the pressure test tool gauge. Allow the system to
stabilize for 5 minutes. The system should
stabilize at the minimum specified pressure. Refer to Pressure Test Specifications, "Item 1" on page 2.
4. Note the pressure regulator reading once
stabilized.
5. Allow the vehicle to stand for an additional
10 minutes. If, after 10 minutes, the pressure reading drops by more than 0.5 psi
from the noted stabilized pressure in the
previous step, the leak test has failed.

Secure the pressure tester and air lines
before making a connection to a pressurized air hose. Failure to properly
secure the pressure tester and air lines
can result in injury to personnel and
damage to equipment.

6. If the pressure test failed in the previous
step, maintain system pressure between
10 to 14 psi and troubleshoot the system
by applying soapy water spray on all
hoses, and hose connections. Repair/
replace leaking hoses (indicated by bubbles forming in the applied soapy water)
and retighten any loose hose connections.
Refer your New Flyer Service Manual for
torque values. Repeat this task until the
test passes.

7. Attach a shop air line to the quick coupler
on the pressure tester

7. When the test has passed, close the shutoff valve and disconnect the pressure test
tool from the vehicle.

1.2.2.

Leak Test Cooling System before Filling

DO NOT pressurize the cooling system
above 25 psi otherwise cooling system

SMB-159

8. Vent the pressure by using the pressure
relief valve on the pressure relief cap.
9. Check the coolant level and fill cooling system as needed. Refer your New Flyer Service Manual for more information.

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 © 2016 New Flyer Industries Canada ULC

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SERVICE MANUAL BULLETIN
SMB-159
1.2.3.

Leak Testing Cooling System after Filling (NOT applicable to 16 psig system)

☞NOTE:

This task requires a Stant (#12704) Engine
Coolant System Pressure Tester Hose and
Head Kit with the hose plugged or capped.
1. Vent the engine cooling system pressure
at the pressure relief cap.
2. Install the pressure test tool.
3. Remove the pressure relief cap.
4. Install the Stant Engine Coolant System
Pressure Tester Hose and Head Kit.
5. Rotate the pressure release bar on the
Stant Pressure Tester Cap in the counterclockwise direction to close the pressure
relief valve.

5 minutes, the pressure drops below 23
psi, press and hold the button on the pressure test tool regulator to re-pressurize the
system to 25 psi and then release the button.
9. Note the pressure regulator reading once
stabilized.
10.Allow the vehicle to stand for an additional
10 minutes. If, after 10 minutes, the pressure reading drops by more than 0.5 psi
from the noted stabilized pressure in the
previous step, the leak test has failed.
11.If the pressure test failed in the previous
step, maintain system pressure between
10 and 14 psi and troubleshoot the system
by applying soapy water spray onto all
hoses, and hose connections. Repair/
replace leaking hoses (indicated by bubbles forming in the applied soapy water)
and retighten any loose hose connections.
Refer your New Flyer Service Manual for
torque values. Repeat this task until the
test passes.

DO NOT pressurize the cooling system
above 25 psi otherwise cooling system
damage can occur. Adjust the pressure
regulator accordingly before opening
the pressure test tool shutoff valve.

12.When the test passes, close the shutoff
valve of the pressure test tool and vent the
coolant system pressure by rotating the
pressure release bar on the Stant Pressure Tester Cap in the clockwise direction.

6. Open the shutoff valve of the pressure test
tool.

13.Disconnect the pressure test tool from the
vehicle and remove the Stant Pressure
Tester Cap.

7. Press and hold the button on the regulator
to pressurize the cooling system to 25 psi.
8. Release the button and allow the system
pressure to stabilize for 5 minutes. If, after

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14.Install the original pressure relief cap to
and fasten the cover back onto the
Schrader valve.

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 © 2016 New Flyer Industries Canada ULC

SMB-159

SERVICE MANUAL BULLETIN
SMB-159
1.2.4.

5 of this task. Otherwise, proceed to the
next step.

Leak Testing Cooling System after
Road Test

4. If the pressure test failed in the previous
step allow the coolant to cool to or below
120°F (49°C) Connect a shop air hose to
the pressure test tool, open the pressure
test tool shutoff valve and maintain system
pressure between 10 and 14 psi.

The cooling system is under pressure
and contains hot fluids that can spill or
spray and cause serious scalding injuries. This task may require close proximity to hot components. Ensure all
safety precautions are taken before proceeding.

5. Troubleshoot the system by applying soapy
water spray onto all hoses, and hose connections. If a leak is detected (bubbles
forming in the soapy water spray), Repair/
replace leaking hoses and retighten any
hose connections. Refer your New Flyer
Service Manual for torque values.
6. When the leak test has passed, close the
shutoff valve of the pressure test tool and
vent the coolant system pressure.

For this test, DO NOT attach the shop
air line to the pressure test tool until
specifically mentioned.
1. While the coolant is still hot (above 180°F
(49°C)) and with the engine running, install
the pressure test tool. Close the pressure
test tool shutoff valve before installing.
2. Verify that the pressure reading is within
the specified range and is stable. Refer to
Pressure Test Specifications, "Item 2" on
page 2.

7. Disconnect the pressure test tool from the
vehicle.

1.3.

Maintenance

☞NOTE:

Refer to the Preventive Maintenance Section of your New Flyer Service Manual for
scheduled maintenance procedures and
intervals.

3. f the pressure is within range and is stable,
the leak test has passed - proceed to step

SMB-159

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 © 2016 New Flyer Industries Canada ULC

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