SB-10057771-5449

INSTRUCTION TO SERVICE
ITS: 5909
SECTION:

231

WRITTEN BY:

Mike Pearson

SUBJECT:

Add EMP Radiator Ground Straps

Coolant System

ITS5909

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.

Bulletin Overview
If dissimilar metals have different electrode potentials, and come into contact with an electrolyte, one metal acts as
anode and the other as cathode. The electro potential difference between the dissimilar metals and the presence of
electrolytic (salt) solutions can be the driving force for an accelerated attack on the anode member of the galvanic
couple. The anode metal dissolves into the electrolyte, and deposits collect on the cathodic metal.
In normal service, voltage levels on coolant pipes have been found to be highly variable and can range anywhere
from roughly -1V to +1V.
These voltage levels are capable of causing highly-accelerated heat exchanger corrosion.
Voltage potential between radiator and coolant pipes can be eliminated by grounding the Mini-Hybrid® cooling system
and coolant pipes to the vehicle chassis.
Note:

If experiencing accelerated radiator corrosion, the work described in this bulletin must be completed
in order to maintain your 3 year EMP radiator warranty coverage. Failure to act promptly may affect
coverage for accelerated corrosion through the radiator due to stray current.

2020056000, 2020056032 and 2020070000

2020069000

Figure 1: Mini-Hybrid® Cooling Systems

Issue
Radiator corrosion has been identified on buses with isolated pipe clamps on vehicles 2010 EPA or newer engines
and Mini-Hybrid® cooling systems including:

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Accelerated corrosion was located by the radiator outlet and was limited to vehicles running in icy
or snowy winter locations. This corrosion has been determined to be caused by stray voltage
carried by the coolant. If the pipes are separated from the radiator via silicone (non-conducting)
hoses and the pipes and radiator are not on the same ground plane, electrolysis can occur between
the pipes and the radiator. Grounding the radiator and pipes to the vehicle chassis eliminates the
electrical potential, stopping the electrolytic corrosion. See Figure 2 for images of accelerated
corrosion.

Figure 2: Gen III Examples.

PROCEDURE:
1. Turn the main battery disconnect switch to the “OFF” position.
2. Raise coach in accordance with the New Flyer Service Manual.
3. Typical coolant tube clamp ground strap mounting hardware orientation, see Figure 3.

Figure 3: Ground Strap Mounting Hardware Orientation

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4. To ground Mini-Hybrid® cooling system shroud, back off the 1/4-20 screw holding the reverse pushbutton bracket
enough to insert provided hook terminal from 50” cable. Insert the terminal between the flange head and the
bracket. There is no need to scrape any powder off the Mini-Hybrid® system shroud as a good ground is
achieved through the PEM nut in the shroud. Torque to 12±2 ft-lbs.
5. Route ground wire to area approximately 4.5” forward of the welded rail (see Figure 7), routing wire away from
any hot surfaces or sharp edges. Use zip ties to secure wire at 18-24” intervals. Adjust cable orientation if
necessary. Proceed with grounding of radiator tubes before securing shroud ground wire.
CAUTION: Grounding to the same welded assembly is required. Grounding to a bolted assembly is NOT
acceptable.

Back off the 1/4-20 screw
holding the reverse pushbutton
bracket enough to insert hook
terminal. Insert the terminal
between the flange head and
the bracket and tighten

50” cable assembly

Figure 4: Existing Rear Corner Support Angle
6. Install one of the 2.5” guillotine clamps from the parts kit to the existing upper radiator tube at the approximate
location and orientation shown in Figure 5, torque to 20 ±2 ft*lbs.
7. Attach the 3/8” ring tongue end of the 16” cable to the bottom stud of the guillotine clamp. Secure and orient the
hardware as shown in Figure 3. Torque the hardware to 20 ±2 ft*lbs.

8. Route ground wire to area approximately 4.5” forward of the welded rail (see Figure 7), routing wire
away from any hot surfaces or sharp edges. Adjust clamp locations on coolant pipes if necessary.

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Upper radiator tube

2.5” Guillotine clamp

3/8” ring tongue end of
the 16” cable assembly
(see figure 2)
16” cable assembly

Figure 5: Radiator and Upper Coolant Tube Ground Strap Installation
9. Install one of the 2.5” guillotine clamps from the parts kit to the existing lower radiator tube at the approximate
location and orientation shown in Figure 6, torque to 20 ±2 ft*lbs.
10. Attach the 3/8” ring tongue end of the 50” cable to the curb side stud of the clamp. Secure using the hardware
supplied with the clamp. Secure and orientate as shown in Figure 3. Torque the hardware to 20 ±2 ft*lbs. Route
the other end of the cable to the rear of the street side engine rail. See Figure 7.

Existing lower
radiator tube

2.5” Guillotine clamp

50” cable assembly
3/8” ring tongue end of
the 50” cable assembly
(see figure 3)

Figure 6: Lower Coolant Tube Ground Strap

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11. Route ground wires to area approximately 4.5” forward of the welded rail (See Figure 7), routing wire away from
any hot surfaces or sharp edges. Use zip ties to secure wire at 18-24” intervals. Adjust clamp locations on coolant
pipes if necessary.

12. Drill a .281Ø (9/32”) hole for grounding stud. Remove structural coating from rail at washer contact to
allow for proper ground contact. Attach upper and lower radiator tubes and shroud grounding straps.
Torque ¼ UNC x 0.75 bolt to 12 ±2 ft-lbs.
13. Apply a protective coating over the installation.
CAUTION:

Fan shroud must not be grounded to the chassis unless the pipes are also grounded.

Figure 7: Common Ground Point on Bus Frame

14. If necessary, lower coach in accordance with the New Flyer Service Manual.
15. Turn the main battery disconnect switch to the “ON” position.

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LABOUR ESTIMATE
Operation
1

Add EMP Radiator Ground Straps

Men

Hours

1

0.5

Labour Time
M X HR
0.5

PARTS REQUIRED
Item

Part Number

1

6449008

Description
Kit-EMP Radiator Ground Strap Rework

Qty.
per
Coach
1

Units

Notes

EA

Vpn 1370056042

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