from the fixing points at the bottom.
23. X3 SERIES – Unbolt the lower support bracket from the
chassis (4 bolts).

X3 SERIES

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

12(35)

24. X3 SERIES – Lift the SCR converter and then remove
the lower support bracket to ease removal of the SCR
converter.

X3 SERIES

25. While proceeding with great care, take the SCR converter out of the compartment through the L.H.
side opening. The SCR converter is heavy. Proceed with the help of a coworker.

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

13(35)

TAKE THE STRAPS AND BRACKETS APART FROM THE DEFECTIVE SCR CONVERTER

It is IMPORTANT to take all the necessary
precautions in order to ease the installation of
the straps and brackets on the replacement SCR
converter. It is very important to position the
straps and the mounting brackets as much as
possible like they were positioned on the
defective SCR converter. Doing so will greatly
facilitate the installation of the SCT in the
compartment.
It is highly recommended to measure and/or
mark the position of the straps on the defective
SCR converter in order to have references for
positioning the straps on the new installation.

ON THE STRAP, DRAW A LINE CENTERED WITH THE DRAIN
FITTING. MEASURE THE UPPER STRAP POSITION IN
RELATION TO THE EMBOSS

ON THE STRAP, DRAW A LINE CENTERED WITH CIRCULAR
EMBOSS. MEASURE THE LOWER STRAP POSITION IN
RELATION TO THE EMBOSS

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

14(35)

26. Remove the mounting straps and brackets from
the SCR converter. Unscrew the bolts identified by
the arrows.

H3 SERIES - UNSCREW THE BOLTS INDICATED BY THE
ARROWS

X3 SERIES - UNSCREW THE BOLTS INDICATED BY THE
ARROWS

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

15(35)

27. H3 SERIES - Take the R.H. side lower bracket
apart from the SCR converter.

H3 SERIES - UNSCREW THE TWO BOLTS INDICATED
BY THE ARROWS

H3 SERIES - UNSCREW THE TWO BOLTS INDICATED
BY THE ARROWS

28. X3 SERIES - Install the insulating blankets recovered from the defective SCR converter. Secure with
stainless steel ties.
IMPORTANT: Make sure that the « V » clearance and the round clearance of the insulation blanket are
placed at the drain fitting and the stud found on the SCR converter respectively.

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

16(35)

29. Install the straps and brackets on the new SCR
converter.

Install the brackets exactly as on the defective SCR

(H3 Series shown)

30. Tighten the bolts just enough to hold the strapss
in place while allowing movement for position
adjustment.

Caution : The bolt head must go into the
chamfered hole

BOLT WITH THE HEAD ON THE PROPER SIDE
(OPPOSITE SIDE OF THE DRAIN TUBE FITTING)

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

17(35)

31. Adjust the straps position in reference to the
emboss.

32. H3 SERIES - Prior final tightening, make sure
that each strap is properly centered on its
respective bracket.

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

18(35)

33. Once properly positioned, apply final torque to
the strap bolts.
FINAL TORQUE: 30-37 lbf-ft

34. H3 SERIES - Install the R.H. side lower bracket
and tighten the bolts (4x) to proper torque.
FINAL TORQUE: 48 lbf-ft

H3 SERIES

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

19(35)

INSTALL THE PRE-SCR NOx SENSOR
35. Apply anti-seize compound on the NOx
sensor threads and then fix onto the DPF
outlet. Secure the harness using nylon ties.
NOx sensor torque: 37 lbf-ft

Return the old NOx sensor with the SCR
converter to Prevost

REINSTALL THE SCR CONVERTER IN ITS COMPARTMENT
36. H3 SERIES - Make sure that there is
a gap of about 1/2″ between the
washer pressed against the bolt head
and the bracket surface where
indicated on the image at right (2
bolts).

H3 SERIES - LOWER BRACKETS

37. While proceeding with great care, insert the SCR converter in the compartment through the opening
using the lifting device. The SCR converter is heavy. Proceed with the help of a coworker. DO NOT
place the SCR converter in final position yet.

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

20(35)

38. H3 SERIES - Install the upper and
lower insulating blankets recovered
from the defective SCR converter.
Secure with stainless steel ties.
IMPORTANT: Make sure that the « V »
clearance and the round clearance of the
insulation blanket are placed at the drain
fitting and the stud found on the SCR
converter respectively.

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

21(35)

39. H3 SERIES - Install the SCR
converter in final position. Rest the
SCR converter at the fixing points on
the chassis with the two upper bolts
secured to both lower brackets.
40. H3 SERIES - Tighten the two bolts to
a firm feel.

H3 SERIES

41. H3 SERIES - Thread in and tighten
the two lower bolts to a firm feel.

H3 SERIES

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

22(35)

42. X3 SERIES – Reinstall the lower support bracket
on the SCR converter.
43. X3 SERIES – Fasten the lower support to the
vehicle chassis.

X3 SERIES

Writer: EL

Special Bulletin

SP18-39
Date

Expiration

Release

Page

11.2018

11.2020

1

23(35)

REINSTALL THE EXHAUST PIPE AND INSULATING BLANKET
44. Clean the sealing surfaces between the after-treatment
SCR converter inlet, the exhaust pipe and the flexible
section.
45. Using a new gasket, position the pipe to the aftertreatment SCR converter and install a new V-band
clamp. Tighten the V-band clamp to specification.
Proceed similarly with the other end of the exhaust
pipe.
Gasket, qty: 2
V-band clamp, qty: 2 (torque=100 lbf-in)

H3 SERIES

X3 SERIES

46. Reinstall the insulating blanket.

H3 SERIES