TIBU-7404

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Technical Information Bulletin
Aftertreatment Injector Is Plugging on Certain CT660 Vocational Trucks{7000}
Media Number -TIBU7404-00
Publication Date -21/02/2014
Date Updated -21/02/2014
Caterpillar: Confidential Yellow
i05608481
Aftertreatment Injector Is Plugging on Certain CT660
Vocational Trucks{7000}
SMCS - 7000
On Highway Truck:
CT660 (S/N: TGA1-UP; TGD1-UP; TRK1-UP; TKL1-UP; TGS1-UP; TJS1-UP; TGT1UP; TSW1-UP; TSY1-UP; TGZ1-UP)
Introduction
A plugged hydrocarbon injector port will result in improper or frequent aftertreatment regenerations.
Problem
Aftertreatment fuel injector is becoming covered in soot and plugging prematurely.
Solution
Proper cleaning procedure of exhaust brake housing for proper Hydrocarbon (HC) Injector operation.
Symptoms
• Frequent regens
• Inability to regen
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• Plugged aftertreatment fuel injector port
• White smoke
Possible Diagnostic Trouble Codes
Table 1
BB Diagnostic Codes
SPN
FMI
MODULE
DESCRIPTION
3556
0
ECM
AFT Fuel Pressure 2 excessively high (Restricted injection)
3556
1
ECM
AFT Fuel Pressure 2 below desired (Possible system leak)
3556
7
ECM
AFT Fuel Injector not responding as expected
3480
0
ECM
AFTFP1 too high while dosing
3480
1
ECM
AFTFP1 too low while dosing
3471
7
ECM
Incorrect dosing pressure, multiple events
3481
7
ECM
AFT Fuel Injector not responding as expected
Parts Information
Replace the below gasket and bolts when servicing the HC Injector [aftertreatment fuel injector (AFI)
and doser injector].
Table 2
Part Number
Description
452-8519
Gasket Injector
376-2720
Bolt- Hex Flange
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Illustration 1
g03569477
The old gasket 376-2628 has been reworked and replaced with 452-8519. The new style gasket will
have the raised center portion of the gasket removed (Figure 1).
Repair Procedure
Background
A plugged HC injector port will result in improper or frequent aftertreatment regenerations (regens).
If the AFI port is plugged use this procedure and the C11 and C13 Engine Service Manual or the C15
Engine Service Manual for additional reference.
Procedure
1. Remove fuel and coolant lines to the HC Injector.
2. Remove the HC Injector from the exhaust brake housing (CT 11 & 13 - exhaust back pressure
assembly; CT 15 - turbocharger exhaust duct).
Note: The HC Injector needle at the tip of the valve is sensitive to damage, set it aside in a safe
location. IT WILL NOT BE CLEANED OR SERVICED
3. Discard the gasket and two M8 x 45 bolts.
4. Disconnect and remove clamp from the exhaust system from the exhaust brake housing
assembly.
Note: Take measures to have sufficient space between the housing and exhaust system so
debris can be removed.
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5. Remove the carbon plugging with a chisel or other appropriate tool.
6. Remove the carbon debris from the exhaust brake housing (A shop vacume can be used).
Note: Any remaining chunks of carbon debris may damage the aftertreatment system or cause
plugging of the PDOC / DOC / DPF.
7. Install the original HC Injector with new gasket and new bolts per the C11 and C13 Service
Manual or C15 Engine Service Manual.
8. Re-install the rest of the exhaust system.
9. Use Engine Diagnostics to perform On Board Filter Cleanliness Test (OBFCT).
Note: If the test is successful/complete and original complaint is resolved, release the unit into
service.
Below are photos of a partially plugged port (fig 2), a completely plugged doser (fig 3) and a clear
port (fig 4)
Illustration 2
g03569474
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Illustration 3
g03569475
Illustration 4
g03569514
Copyright 1993 - 2014 Caterpillar Inc.
All Rights Reserved.
Wed Mar 5 16:48:28 CST 2014
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