FSB 642-001

Mack Trucks
Greensboro, NC USA
Field Service Bulletin
Trucks
Date
Group
No.
Release
Page
3.2017
642
001
01
1(37)
Static Steering, Repair
GU
FSB 642-001, Static Steering, Repair
(March 2017)
Certain GU trucks equipped with forward steer axles (18,000 lb rated front axles) and built
from 2012, may experience issues with static steering while sitting still. There is not enough
ability with a single steering gear to overcome certain turning frictions. To repair this issue,
an assist steering gear and different power steering pump are added to these trucks. On
trucks built after 2012 the additional ports for the assist steering gear hydraulic lines are not
present on the existing steering gear. Therefore, the existing steering gear is replaced with a
new one in this repair procedure. Follow the repair procedure outlined in this Field Service
Bulletin (FSB).
Note: This bulletin does not apply to MACK Trucks Australia.
PV729-FSB642-001_M
USA138684852
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
Required Parts
Static Steering, Repair Parts
Item #
Description
Part Number
Qty
1
STEERING ROD, CT-AF ASSIST
20923573
1
2
HEXAGON SCREW, M16 * 100
993909
1
3
FLANGE LOCK NUT, M16 * 18.3
990954
1
4
WASHER, 17 * 30 * 6
994882
2
5
SPLIT PIN
25092079
2
6
CLAMP
25089705
2
7
FLANGE SCREW
25087147
2
8
NUT RETAINER, FLANGE
20706309
2
9
HOSE ASSEMBLY, POWER STEERING
20924991
1
10
HOSE ASSEMBLY, POWER STEERING
20924988
1
11
STEERING GEAR, SD110, 180 BAR
20897097
1
12
STEERING GEAR, ASSIST
20897099
1
13
ELBOW NIPPLE, 12.7XM16X1.5
20469515
1
14
FITTING
25102426
1
15
NIPPLE, M16*3/4-16 SAE JIC37
8397884
1
16
ELBOW NIPPLE, 12.7XM16X1.5
20469515
2
17
HEXAGON NUT, M20*18
990973
3
18
HEXAGON SCREW, M20*140
992482
1
19
WASHER, 21*36*5.8
994884
7
20
HEXAGON SCREW, M20*70
992935
1
21
HEXAGON SCREW, M20*130
992481
2
22
PITMAN ARM
25109405
1
23
TANDEM PUMP, 25LMIN/25CC/REV-200E
21745619
1
24
SPINDLE ARM
25110366
1
25
FLANGE SCREW, SPECIAL
1079490
2
26
CASTLE NUT
10506
1
Page
2(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
Decommissioning the Truck for Repair
You must read and understand the precautions and guidelines in Service Information,
group 60, "General Safety Practices, Steering, Front Axle, & Suspension" before
performing this procedure. If you are not properly trained and certified in this procedure,
ask your supervisor for training before you perform it.
NOTE: Information is subject to change without notice. Illustrations are used for reference
only and can differ slightly from the actual vehicle being serviced. However, key
components addressed in this information are represented as accurately as possible.
DANGER
Do not attempt to repair or service this vehicle without having sufficient training, the
correct service literature and the proper tools. Failure to follow this could make the vehicle
unsafe and lead to serious personal injury or death.
1 Park the vehicle on a level surface.
2 Apply the parking brake.
3 Place the transmission in neutral or park.
4 Install the wheel chocks on the rear wheels.
W7086748
Page
3(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
5 Disconnect the cable from the battery’s negative terminal.
W3086747
6 Using either coolant extractor (part number 88870007) or drain hose (part number
9996049), drain the cooling system.
Static Steering, Repair Procedure
1 With assistance, remove the bumper assembly.
W7113455
Page
4(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
2 With assistance, remove the hood assembly.
W7113456
3 Using a jack, lift the front left and right sides of the truck by the frame and support the
frame with jack stands.
4 With all of the weight removed from the drive axles, lift and support the drive axle
assembly.
DANGER
Position a suitable jack under the axle housing pinion to prevent the axle from rolling
over.
5 Remove the front wheels.
Note: left side shown.
W7113457
Page
5(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
6 Remove the recirculation shield or cut the shield at the condenser high and low pressure
pipes to allow condenser removal without reclaiming refrigerant.
W6120675
7 Without disconnecting the condenser piping, position the condenser out of the way and
secure until it is reinstalled.
W6120676
Page
6(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
8 Remove the upper hose as shown.
W6120677
9 Remove the left side charge air pipe.
W6120678
Page
7(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
10 Remove the right side charge air pipe.
W6120679
11 Remove the static fill hose.
W6120680
Page
8(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
12 Disconnect the de-aeration hose.
W6120681
13 Using a drip pan, remove the lower radiator hose.
W6120682
Page
9(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
14 Using a drip pan, remove the power steering cooler hoses.
W6120683
15 Attach a lifting tool to the cooling package and secure until removal.
16 Remove the left side cooling package hardware as shown in the figure below.
W6120684
Page
10(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
17 Remove the right side cooling package hardware as shown.
W6120685
18 Using the lifting tool and assistance, remove the cooling package.
W6120686
Page
11(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
19 Using the measurements in the figure below, mark, cut, and drill holes in the frame as
shown to install the assist steering gear.
Note: The view in the figure below is from the inside of the frame rail.
Note: All cuts and holes in the frame must be ground smooth in the horizontal line of the
frame with no edges to prevent stress risers.
W6120687
20 Using the measurement in the figure below, cut and shape the upper rail flange as shown.
W6120688
Page
12(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
21 Use the image below as a reference for mount locations.
Note: The view shown below is from outside of the frame rail.
W6120690
22 Install the assist steering gear fittings as shown.
W6120693
Page
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Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
23 Install assist steering gear.
W6120695
24 Install the assist steering gear pitman arm.
Note: Use alignment marks when installing pitman arm.
W6120700
Page
14(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
25 Install the spindle arm and fasteners as shown.
26 Tighten the fasteners to 750 ± 75 Nm (553 ± 55 ft-lb)
W6120697
27 Position the assist steering gear draglink rod at the steering knuckle and pitman arm as
shown as shown.
28 Install the castle nut.
29 Tighten the castle nut to 200 Nm (147 ft-lb) minimum.
30 Turn the castle nut CLOCKWISE until the next castle nut slot aligns with the hole in the
draglink rod ball socket.
31 Install the split pin.
W6120704
Page
15(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
32 Install the pinch bolt fastener, nut, and flat washers on the pitman arm.
33 Tighten the fasteners to 275 ± 20 Nm (202 ± 14 ft-lb).
W6120707
34 If applicable, locate the grease fittings, and lubricate the draglink rod.
35 Tighten the assist steering gear pitman arm bolt to 475 Nm (350 ft-lb).
Note: Continue to tighten until the notches align with the locking tabs, then bend the
locking tabs into the notches.
W6120708
Page
16(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
36 Remove the steering shaft support bearing fasteners.
W6120709
37 Remove the pinch bolt and nut. Remove the steering shaft from the steering gear and
position out of the way.
CAUTION
Do not allow the steering gear shaft to rotate a full revolution after or damage may
occur to other steering components.
W6120711
Page
17(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
38 Remove the main steering gear pitman arm fastener and lock tab.
W6120712
39 Using pitman arm puller tool (part number 3596372K), remove the pitman arm from the
steering gear with the draglink rod attached.
W6120713
Page
18(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
40 With a drain pan under the steering gear to capture hydraulic fluid, remove hydraulic
supply and return lines from the steering gear.
W6120714
41 With assistance and a suitable lifting device, remove the fasteners securing the steering
gear and remove the steering gear.
W6120715
Page
19(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
42 Remove the existing fittings from the steering gear and transfer them to the replacement
steering gear.
Note: Record the position of the fittings for transfer to the replacement steering gear.
W6120716
43 With assistance and a suitable lifting device, position the steering gear on the frame rail
and install the fasteners.
44 Tighten the fasteners to 450 ± 40 Nm (331 ± 29 ft-lb)
W6120715
Page
20(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
45 Install the feed and return lines to the steering gear.
W6120714
46 Install the assist steering hoses and clamps as shown.
W6120717
Part Number
Location
20924988
Back of the steering gear to the front of the assist gear.
20924991
Front of the steering gear to the top of the assist gear.
Page
21(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
47 Install the pinch bolt to the steering gear shaft and tighten to 65 ± 75 Nm (48 ± 55 ft-lb).
W6120711
48 Install and secure the steering shaft support bearing.
49 Tighten the fasteners to 48 ± 8 Nm (35 ± 5 ft-lb).
W6120709
Page
22(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
50 Position the pitman arm on steering gear.
51 Install the pitman arm fastener and lock tab.
W6120718
52 Tighten the assist steering gear pitman arm bolt to 475 Nm (350 ft-lb).
Note: Continue to tighten until the notches align with the locking tabs, then bend the
locking tabs into the notches.
W6120712
Page
23(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
53 With a drain pan under the power steering pump to capture hydraulic fluid, remove power
steering pump supply hose.
W6120719
54 Remove steering pump pressure hose.
W6120720
Page
24(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
55 Remove fuel lines from the tandem pump.
W6120721
56 Remove the tandem pump assembly.
W6120722
Page
25(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
57 Remove the fitting from the removed pump and transfer it to the replacement pump.
Tighten the fitting to 57 ± 5 Nm (42 ± 3 ft-lb).
W6120723
58 Install the replacement power steering pump assembly and tighten the fasteners to
specification.
W6120722
Page
26(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
59 Using new sealing washers, install the fuel lines to the tandem pump.
W6120721
60 Install the power steering pump pressure hose.
W6120720
Page
27(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
61 Using new sealing washers, install the power steering pump supply hose. Tighten the bolt
to 80 ± 10 Nm (59 ± 3 ft-lb).
W6120719
62 Using a suitable lifting tool and assistance, install the cooling package.
W6120686
Page
28(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
63 Install the right side cooling package hardware as shown.
W6120685
64 Install the left side cooling package hardware as shown.
W6120684
Page
29(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
65 Install the power steering cooler hoses.
W6120683
66 Install the lower radiator hose.
W6120682
Page
30(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
67 Install the de-aeration hose.
W6120681
68 Install the static fill hose.
W6120680
Page
31(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
69 Install the right side charge air pipe.
W6120679
70 Install the left side charge air hose.
W6120678
Page
32(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
71 Install the upper radiator hose.
W6120677
72 Install the condenser.
W6120676
Page
33(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
73 If applicable, install the recirculation shield.
W6120675
74 Using the approved coolant and coolant extractor (part number 88870007), fill the cooling
system to the proper levels.
75 Fill power steering system with oil to the proper levels.
76 Prime the fuel system.
77 Connect the cable to the battery’s negative terminal.
W3086758
Page
34(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
78 Bleed the air from steering system in accordance with UCHP operation code 6422-05-0301.
79 Install the left and right steer axle wheels.
Note: Left side shown.
80 Tighten the wheel nuts to 610 Nm (450 ft-lb).
W7113457
81 Lift the vehicle with a jack, remove the jack stands and lower vehicle.
82 Using the appropriate lifting and assistance, install the hood.
W7113456
Page
35(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
83 With assistance, install the bumper assembly.
W7113455
Commissioning the Truck for Operation
1 Remove the wheel chocks from the rear wheels.
W7086759
2 Test drive the vehicle for proper operation. After the test drive, re-check the fluid levels.
Page
36(37)
Mack Trucks
Field Service Bulletin
Date
3.2017
Group
No.
Release
642
001
01
Reimbursement
This repair may be eligible for reimbursement if a product
failure was experienced within time and mileage limits of
the applicable Warranty coverage. Reimbursement is
obtained via the normal claim handling process.
UCHP Reimbursement
Claim Type (used only when uploading from the Dealer
Bus. Sys.)
01
Labor Code
Primary Labor Code (Static Steering, Repair)
6422-18-02-01
7.3 hrs.
Causal Part
20897099
MACK Trucks North America reserves the right to make any changes in design or to make
additions to or upon its products without incurring any obligations to install the same on
vehicles previously built.
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