Workhorse W Series User manual

WORKHORSE CUSTOM CHASSIS
Service Manual
W SeriesWCC
SECTION
6.2
PAGE
1Engine Mechanical
W Series Chassis
TOC
© 2006 WorkhorseCustom Chassis — All Rights Reserved
2006
ENGINE MECHANICAL

WORKHORSE CUSTOM CHASSIS
Service Manual
W SeriesWCC
SECTION
6.2
PAGE
2Engine Mechanical
W Series Chassis
TOC
© 2006 WorkhorseCustom Chassis — All Rights Reserved
TABLE OF CONTENTS
8.1L (L18) ENGINE.............................................................4
Fastener Tightening Specifications L18 (8.1L) Engine ...4
Engine Mechanical Specifications L18 (8.1L) Engine.....8
Diagnostic Starting Point - Engine Mechanical —
(8.1l/ L18 Engine)........................................................14
Base Engine Misfire with Abnormal Valve Train Noise .18
Base Engine Misfire with Coolant Consumption ...........19
Base Engine Misfire with Excessive Oil Consumption..19
Engine Noise on Start-Up, but Only Lasting a Few
Seconds ......................................................................20
Upper Engine Noise, Regardless of Engine Speed ......21
Lower Engine Noise, Regardless of Engine Speed ......23
Engine Noise Under Load.............................................25
Engine Will Not Crank - Crankshaft Will Not Rotate .....26
Coolant in Combustion Chamber..................................27
Coolant in Engine Oil ....................................................28
Engine Compression Test .............................................29
Cylinder Leakage Test ..................................................30
Oil Consumption Diagnosis...........................................32
Oil Pressure Diagnosis and Testing ..............................33
Oil Leak Diagnosis ........................................................34
Drive Belt Chirping, Squeal, and Whine Diagnosis.......37
Diagnostic Aids .............................................................42
Drive Belt Falls Off and Excessive Wear Diagnosis......46
Base Engine Misfire with Abnormal Valve Train
Noise............................................................................50
Crankcase Ventilation System Description L18 (8.1L)
Engine.........................................................................51
Drive Belt System Description ......................................53
Drive Belt Chirping, Squeal, and Whine Diagnosis.......54
Drive Belt Rumbling and Vibration Diagnosis ...............59
Drive Belt Falls Off and Excessive Wear Diagnosis......60
Drive Belt Tensioner Diagnosis .....................................64
Engine Component Description (LQ4/LR4) ..................64
Lubrication Description .................................................67
Separating Parts ...........................................................68
Replacing Engine Gaskets............................................69
Use of Room Temperature Vulcanizing (RTV) and
Anaerobic Sealer.........................................................71
4.8L/6.0 (LR4/LQ4) ENGINES..........................................75
Fastener Tightening Specifications
(LR4/LQ4 VIN V/U) .....................................................75
Engine Mechanical Specifications (LR4 VIN V) ............80
Engine Mechanical Specifications (LQ4 VIN U)............84
Engine Identification......................................................89
Diagnostic Starting Point - Engine Mechanical
(LR4 VIN V & LQ4 VIN U)...........................................89
Base Engine Misfire without Internal Engine Noises ....92
Base Engine Misfire with Abnormal Internal Lower
Engine Noises.............................................................95
Base Engine Misfire with Abnormal Valve Train
Noise............................................................................96
Base Engine Misfire with Coolant Consumption ...........97
Base Engine Misfire with Excessive Oil Consumption..97
Engine Noise on Start-Up, but Only Lasting a Few
Seconds ......................................................................98
Upper Engine Noise, Regardless of Engine Speed ......99
Lower Engine Noise, Regardless of Engine Speed ....101
Engine Noise Under Load...........................................102
Engine Will Not Crank - Crankshaft Will Not Rotate ...103
Coolant in Combustion Chamber................................105
Coolant in Engine Oil ..................................................106
Engine Compression Test ...........................................107

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© 2006 WorkhorseCustom Chassis — All Rights Reserved
Cylinder Leakage Test ................................................108
Oil Consumption Diagnosis.........................................110
Oil Pressure Diagnosis and Testing ............................ 111
Oil Leak Diagnosis ......................................................113
Crankcase Ventilation System Inspection/Diagnosis
LQ4/LR4 Engine ....................................................... 116
Drive Belt Chirping, Squeal, and Whine Diagnosis..... 118
Drive Belt Rumbling and Vibration Diagnosis .............123
Drive Belt Falls Off and Excessive Wear Diagnosis....127

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W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
FASTENER TIGHTENING SPECIFICATIONS
L18 (8.1L) ENGINE
Application
Specification
Metric English
Air Cleaner Outlet Duct Clamp 4 N·m 35 lb in
Air Conditioning (A/C) Belt Tensioner Bolt 50 N·m 37 lb ft
Battery Cable Channel Bolt 9 N·m 80 lb in
Camshaft Position (CMP) Sensor Bolt 12 N·m 106 lb in
Camshaft Retainer Bolt 12 N·m 106 lb in
Camshaft Sprocket Bolt 30 N·m 22 lb ft
Connecting Rod Nut - First Pass 30 N·m 22 lb ft
Connecting Rod Nut - Final Pass 90 degrees
Crankshaft Balancer Bolt 255 N·m 189 lb ft
Crankshaft Bearing Cap Bolts - First Pass 30 N·m 22 lb ft
Crankshaft Bearing Cap Bolts - Final Pass 90 degrees
Crankshaft Bearing Cap Studs - First Pass 30 N·m 22 lb ft
Crankshaft Bearing Cap Studs - Final Pass 80 degrees
Crankshaft Oil Deflector Nut 50 N·m 37 lb ft
Crankshaft Position (CKP) Sensor Bolt 12 N·m 106 lb in
Crossbar Bolt 100 N·m 74 lb ft
Cylinder Head Bolts - In Sequence
• First Pass 30 N·m 22 lb ft
• Second Pass 30 N·m + 120 degrees 22 lb ft + 120 degrees
• Final Pass - Long Bolts #1, 2, 3, 6, 7, 8, 9, 10, 11, 14, 16, 17 60 degrees
• Final Pass - Medium Bolts #15, 18 45 degrees
• Final Pass - Short Bolts #4, 5, 12, 13 30 degrees
Cylinder Head Coolant Hole Plug 50 N·m 37 lb ft
Drive Belt Idler Pulley Bolt 50 N·m 37 lb ft
8.1L (L18) ENGINE

WORKHORSE CUSTOM CHASSIS
Service Manual
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W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
Drive Belt Tensioner Bolt 50 N·m 37 lb ft
Engine Block Coolant Drain Hole M28 Plug - Left Front 60 N·m 44 lb ft
Engine Block Coolant Drain Hole Plug - Side 30 N·m 22 lb ft
Engine Block Coolant Heater 50 N·m 37 lb ft
Engine Block Oil Gallery Plug - Front 20 N·m 15 lb ft
Engine Block Oil Gallery Plug - Rear 30 N·m 22 lb ft
Engine Block Oil Gallery Plug - Side 30 N·m 22 lb ft
Engine Block Oil Gallery Plug - Top 20 N·m 15 lb ft
Engine Coolant Crossover Bolt 50 N·m 37 lb ft
Engine Coolant Temperature (ECT) Senso 50 N·m 37 lb ft
Engine Coolant Temperature (ECT) Sensor Bracket Bolt 50 N·m 37 lb ft
Engine Harness Bolt 5 N·m 44 lb in
Engine Harness Ground Bolt 16 N·m 12 lb ft
Engine Harness Stud 10 N·m 89 lb in
Engine Lift Bracket Bolt 40 N·m 30 lb ft
Engine Mount-to-Engine Bolt 50 N·m 37 lb ft
Engine Shield Bolt 20 N·m 15 lb ft
Engine Sight Shield Bracket Nut 5 N·m 44 lb in
Engine Wiring Harness Bolt 16 N·m 12 lb ft
Evaporative Emission (EVAP) Canister Purge Solenoid Valve Bolt 8 N·m 71 lb in
Exhaust Gas Recirculation (EGR) Valve Opening Cover Nut 22 N·m 16 lb ft
Exhaust Gas Recirculation (EGR) Valve Opening Cover Stud 7 N·m 62 lb in
Exhaust Manifold Center Bolt 5 N·m 26 lb ft
Exhaust Manifold Nut 16 N·m 12 lb ft
Exhaust Manifold Stud 20 N·m 15 lb ft
Exhaust Manifold Heat Shield Bolt 25 N·m 18 lb ft
Exhaust Manifold Heat Shield Nut 25 N·m 18 lb ft
Flywheel Bolt - First Pass 40 N·m 30 lb ft
Flywheel Bolt - Second Pass 80 N·m 59 lb ft

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Service Manual
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6Engine Mechanical
W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
Flywheel Bolt - Final Pass 100 N·m 74 lb ft
Front Cover Bolt - First Pass 6 N·m 53 lb in
Front Cover Bolt - Final Pass 12 N·m 106 lb in
Fuel Rail Bolt/Stud 12 N·m 106 lb in
Heater Hose Bracket Bolt 50 N·m 37 lb ft
Hood Hinge Bolt 25 N·m 18 lb ft
Ignition Coil Bolt 12 N·m 106 lb in
Ignition Coil Wiring Harness Bolt 12 N·m 106 lb in
Intake Manifold Bolts - First Pass In Sequence 5 N·m 44 lb in
Intake Manifold Bolts - Second Pass In Sequence 8 N·m 71 lb in
Intake Manifold Bolts - Third Pass In Sequence 12 N·m 106 lb in
Intake Manifold Bolt - Final Pass In Sequence 15 N·m 11 lb ft
J 36857 Bolt 40 N·m 30 lb ft
J 42847 Bolt 50 N·m 37 lb ft
Knock Sensor 20 N·m 15 lb ft
Knock Sensor Heat Shield Bolt 12 N·m 106 lb in
Manifold Absolute Pressure (MAP) Sensor Bolt 12 N·m 106 lb in
Oil Cooler Hose Fittings 23 N·m 17 lb ft
Oil Fill Tube Bolt 12 N·m 106 lb in
Oil Level Sensor 20 N·m 15 lb ft
Oil Pan Bolt - First Pass 10 N·m 89 lb in
Oil Pan Bolt - Final Pass 25 N·m 18 lb ft
Oil Pan Drain Plug 28 N·m 21 lb ft
Oil Pan Skid Plate Bolt 20 N·m 15 lb ft
Oil Pressure Sensor 30 N·m 22 lb ft
Oil Pump Bolt 75 N·m 56 lb ft
Oil Pump Cover Bolt 12 N·m 106 lb in
Oil Pump Drive Bolt 25 N·m 18 lb ft
Power Steering Pump Bracket Bolt/Nut 50 N·m 37 lb ft

WORKHORSE CUSTOM CHASSIS
Service Manual
W SeriesWCC
SECTION
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PAGE
7Engine Mechanical
W Series Chassis
TOC
© 2006 WorkhorseCustom Chassis — All Rights Reserved
Power Steering Pump Bracket Stud 20 N·m 15 lb ft
Spark Plug 30 N·m 22 lb ft
Throttle Body Nu 10 N·m 89 lb in
Throttle Body Stud 12 N·m 106 lb in
Valve Lifter Guide Retainer Bolt 25 N·m 18 lb ft
Valve Rocker Arm Cover Bolt - First Pass 6 N·m 53 lb in
Valve Rocker Arm Cover Bolt - Final Pass 12 N·m 106 lb in
Valve Rocker Arm Nut 35 N·m 26 lb ft
Valve Rocker Arm Stud 50 N·m 37 lb ft
Water Outlet Bolt/Stud 30 N·m 22 lb ft
Water Pump Bolt - First Pass 25 N·m 18 lb ft
Water Pump Bolt - Final Pass 50 N·m 37 lb ft
Water Pump Pulley Bolt 25 N·m 18 lb ft

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Service Manual
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SECTION
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8Engine Mechanical
W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
ENGINE MECHANICAL SPECIFICATIONS
L18 (8.1L) ENGINE
L18 Engine Application
Specification
Metric English
General
• Engine Type V8
• Displacement 8.1L 496 CID
• RPO L18
• VIN - Light Duty G
• VIN - Medium Duty G
• Bore 107.95 mm 4.25 in
• Stroke 111.0 mm 4.37 in
• Compression Ratio 9.1:1
• Firing Order 1-8-7-2-6-5-4-3
• Spark Plug Gap 1.52 mm 0.06 in
Block
• Crankshaft Main Bearing Bore Diameter 74.606-74.622 mm 2.9372-2.9379 in
• Cylinder Bore Diameter - Production 107.95-107.968 mm 4.25-4.2507 in
• Cylinder Bore Diameter - Service 107.94-107.99 mm 4.2496-4.2516 in
• Cylinder Bore Out-of-Round - Production, Maximum Minus Minimum
Bore Diameter
0.018 mm 0.0007 in
• Cylinder Bore Out-of-Round - Service, Maximum Minus Minimum Bore
Diameter
0.05 mm 0.002 in

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W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
• Cylinder Bore Taper - Production 0.018 mm 0.0007 in
• Cylinder Bore Taper - Service Thrust Axis 0.05 mm 0.002 in
• Cylinder Bore Taper - Service Pin Axis 0.05 mm 0.002 in
• Cylinder Head Deck Height - from Centerline of Crankshaft 259.875-260.125 mm 10.231-10.241 in
• Cylinder Head Deck Surface Flatness - Entire Face 0.1 mm 0.004 in
• Cylinder Head Deck Surface Flatness - Within 150 mm (6 in) 0.05 mm 0.002 in
• Valve Lifter Bore Diameter 21.417-21.443 mm 0.843-0.844 in
Camshaft
• Camshaft Bearing Inside Diameter 49.548-49.573 mm 1.9507-1.9517 in
• Camshaft Journal Diameter 49.472-49.522 mm 1.9477-1.9497 in
• Camshaft Lobe Lift - Exhaust 6.973-7.075 mm 0.2745-0.2785 in
• Camshaft Lobe Lift - Intake 6.924-7.026 m 0.2726-0.2766 in
• Camshaft Runout - Production 0.051 mm 0.002 in
• Camshaft Runout - Service 0.076 mm 0.003 in
Connecting Rod
• Connecting Rod Bearing Clearance - Production 0.033-0.068 mm 0.0013-0.0027 in
• Connecting Rod Bearing Clearance - Service 0.033-0.081 mm 0.0013-0.0032 in
• Connecting Rod Side Clearance 0.384-0.686 mm 0.0151-0.027 in
Crankshaft
• Connecting Rod Journal Diameter 55.854-55.87 mm 2.199-2.1996 in

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W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
• Connecting Rod Journal Out-of-Round - Production 0.0102 mm 0.0004 in
• Connecting Rod Journal Taper - Production 0.0102 mm 0.0004 in
• Crankshaft End Play 0.127-0.35 mm 0.005-0.0138 in
• Crankshaft Main Bearing Clearance - #1, #2, #3, #4 Production 0.022-0.057 mm 0.0008-0.0022 in
• Crankshaft Main Bearing Clearance - #5 Production 0.034-0.069 mm 0.0013-0.0027 in
• Crankshaft Main Bearing Clearance - #1, #2, #3, #4 Service 0.022-0.089 mm 0.0008-0.0035 in
• Crankshaft Main Bearing Clearance - #5 Service Limit 0.035-0.102 mm 0.0014-0.004 in
• Crankshaft Main Journal Diameter 69.805-69.822 mm 2.7482-2.7489 in
• Crankshaft Main Journal Out-of-Round - Production 0.0102 mm 0.0004 in
• Crankshaft Main Journal Taper - Production 0.0102 mm 0.0004 in
• Crankshaft Runout - Production 0.05 mm 0.002 in
• Crankshaft Runout - Service 0.065 mm 0.0026 in
Cylinder Head
• Cylinder Head Height/Thickness 259.875-260.125 mm 10.231-10.241 in
• Surface Flatness - Block Deck 0.05 mm 0.002 in
• Surface Flatness - Exhaust Manifold Deck 0.102 mm 0.004 in
• Surface Flatness - Intake Manifold Deck 0.08 mm 0.003 in
Exhaust Mainfold
• Surface Flatness 0.254 mm 0.01 in
Lubrication System

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W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
• Oil Capacity - Without Filter 5.7L 6.0 Qts
• Oil Capacity - With Filter 6.15L 6.5 Qts
• Oil Pressure - Minimum 34 kPa @ 1,000 RPM 5 psi @ 1,000 RPM
• Oil Pressure - Minimum 69 kPa @ 2,000 RPM 10 psi @ 2,000 RPM
Piston Rings
Piston Ring End Gap
• First Compression Ring - Production 0.3-0.45 mm 0.012-0.018 in
• First Compression Ring - Service 0.45-0.675 mm 0.018-0.027 in
• Second Compression Ring - Production 0.45-0.65 mm 0.017-0.025 in
• Second Compression Ring - Service 0.675-0.975 mm 0.026-0.039 in
• Oil Control Ring - Production 0.249-0.759 mm 0.0098-0.0299 in
• Oil Control Ring - Service 0.373-1.138 mm 0.015-0.045 in
Piston Ring-to-Groove Clearance
• First Compression Ring 0.031-0.074 mm 0.0012-0.0029 in
• Second Compression Ring 0.031-0.074 mm 0.0012-0.0029 in
• Oil Control Ring 0.051-0.203 mm 0.002-0.008 in
Piston and Pins
Piston
• Piston Diameter Not Measurable Not Measurable
• Piston-to-Bore Clearance Interference Fit Interference Fit

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Pin
• Pin-Piston Pin Fit in Connecting Rod Bore-Production 0.010-0.023 mm 0.0004-0.0009 in
• Pin-Piston Pin Fit in Connecting Rod Bore-Service 0.010-0.023 mm 0.0004-0.0009 in
• Pin-Piston Pin Clearance-to-Piston Pin Bore-Production 0.003-0.011 mm 0.00019-0.00043 in
• Pin-Piston Pin Clearance-to-Piston Pin Bore-Service 0.003-0.011 mm 0.00019-0.00043 in
• Pin-Piston Pin Diameter 26.416-26.419 mm 1.039-1.040 in
Valve System
Valve
• Valve Face Angle - Exhaust 45 degrees
• Valve Face Angle - Intake 45 degrees
• Valve Head Diameter - Exhaust 43.69 mm 1.72 in
• Valve Head Diameter - Intake 55.63 mm 2.19 in
• Valve Lash - Exhaust Net Lash Net Lash
• Valve Lash - Intake Net Lash Net Lash
• Valve Seat Angle - Exhaust 46 degrees
• Valve Seat Angle - Intake 46 degrees
• Valve Seat Runout - Exhaust 0.05 mm 0.002 in
• Valve Seat Runout - Intake 0.05 mm 0.002 in
• Valve Seat Width - Exhaust 1.651-2.159 mm 0.060-0.095 in
• Valve Seat Width - Intake 0.8-1.2 mm 0.03-0.06 in

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• Valve Stem Diameter - Exhaust 9.431-9.449 mm 0.3713-0.372 in
• Valve Stem Diameter - Intake 9.436-9.454 mm 0.3715-0.3722 in
• Valve Stem-to-Guide Clearance - Exhaust - Production 0.03-0.079 mm 0.0012-0.0031 in
• Valve Stem-to-Guide Clearance - Intake - Production 0.025-0.074 mm 0.001-0.0029 in
• Valve Stem-to-Guide Clearance - Exhaust - Service 0.03-0.104 mm 0.0012-0.0041 in
• Valve Stem-to-Guide Clearance - Intake - Service 0.025-0.099 mm 0.001-0.0039 in
Rocker Arms
• Valve Rocker Arm Ratio 1.7:1
Valve Springs
• Valve Spring Free Length 56.35 mm 2.218 in
• Valve Spring Installed Height 45.92-46.69 mm 1.808-1.838 in
• Valve Spring Load - Closed 381-419 N at 45.92 mm 86-94 lb at 1.808 in
• Va l v e S p ri n g L o ad - O pen 9 6 4 -10 5 6 N a t
33.99 mm
216 - 2 3 6 lb a t
1.338 in
•

WORKHORSE CUSTOM CHASSIS
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W Series Chassis
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© 2006 WorkhorseCustom Chassis — All Rights Reserved
DIAGNOSTIC STARTING POINT - ENGINE MECHANICAL — (8.1L/ L18 ENGINE)
Begin the system diagnosis by reviewing the Disassembled Views, Engine Component Description , Lubrication
Description , New Product Information , and the Drive Belt System Description. Reviewing the description and
operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists.
Reviewing the description and operation information will also help you determine if the condition described by the
customer is normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct procedure for
diagnosing the system and where the procedure is located.
Symptoms - Engine Mechanical
Strategy Based Diagnostics
Perform a Diagnostic System Check - Vehicle before using the symptom tables, if applicable.
Review the system operations in order to familiarize yourself with the system functions. Refer to Disassembled
Views , Engine Component Description , Drive Belt System Description , Lubrication Description and New Product
Information .
All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach
for repairing all systems. The diagnostic flow may always be used in order to resolve a system condition. The
diagnostic flow is the place to start when repairs are necessary.
Visual/Physical Inspection
• Inspect for aftermarket devices which could affect the operation of the engine. Refer to Checking Aftermarket Accessories.
• Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the
symptom.
• Inspect for the correct oil level, proper oil viscosity, and correct filter application.
• Verify the exact operating conditions under which the condition exists. Note factors such as engine RPM, ambient
temperature, engine temperature, amount of engine warm-up time, and other specifics.
• Compare the engine sounds, if applicable, to a known good engine and ensure you are not trying to correct a normal
condition.

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Intermittent
Test the vehicle under the same conditions that the customer reported in order to verify the system is operating
properly.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
• Base Engine Misfire without Internal Engine Noises
• Base Engine Misfire with Abnormal Internal Lower Engine Noises
• Base Engine Misfire with Abnormal Valve Train Noise
• Base Engine Misfire with Coolant Consumption
• Base Engine Misfire with Excessive Oil Consumption
• Engine Noise on Start-Up, but Only Lasting a Few Seconds
• Upper Engine Noise, Regardless of Engine Speed
• Lower Engine Noise, Regardless of Engine Speed
• Engine Noise Under Load
• Engine Will Not Crank - Crankshaft Will Not Rotate
• Coolant in Combustion Chamber
• Coolant in Engine Oil
• Engine Compression Test
• Cylinder Leakage Test
• Oil Consumption Diagnosis
• Oil Pressure Diagnosis and Testing
• Oil Leak Diagnosis
• Drive Belt Chirping, Squeal, and Whine Diagnosis
• Drive Belt Rumbling and Vibration Diagnosis
• Drive Belt Falls Off and Excessive Wear Diagnosis

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Cause Correction
Abnormalities, such as severe cracking, bumps, or missing areas in the
accessory drive belt
Abnormalities in the accessory drive system and/or components may
cause engine RPM variations and lead to a misfire diagnostic trouble code
(DTC). A misfire code may be present without an actual misfire condition.
Replace the drive belt. Refer to Drive Belt Replacement - Accessory
Worn, damaged, or mis-aligned accessory drive components or excessive
pulley runout
A misfire code may be present without an actual misfire condition.
1. Inspect the components.
2. Repair or replace the components, as required.
Loose or improperly installed engine flywheel or crankshaft balancer
A misfire code may be present without an actual misfire condition.
Repair or replace the flywheel and/or balancer, as required. Refer to
Engine Flywheel Replacement or Crankshaft Balancer Replacement.
Restricted exhaust system
A severe restriction in the exhaust flow can cause significant loss of
engine performance and may set a DTC. Possible causes of restrictions
include collapsed or dented pipes or plugged mufflers and/or catalytic
converters.
Repair or replace, as required.
Improperly installed or damaged vacuum hoses Repair or replace, as required.
Improper sealing between the intake manifold and cylinder heads or
throttle body
Replace the intake manifold, gaskets, cylinder heads, and/or throttle
body, as required.
Improperly installed or damaged manifold absolute pressure (MAP)
sensor
The sealing grommet of the MAP sensor should not be torn or damaged.
Repair or replace the MAP sensor, as required.
Worn or loose rocker arms Repair or replace the valve rocker arms, as required.

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Worn or bent push rods Replace the push rods.
Sticking valves
Carbon buildup on the valve stem and/or seat can cause the valve to not
close properly.
Repair or replace, as required.
Excessively worn or mis-aligned timing chain Repair or replace the timing chain, camshaft retainer, and sprockets,
as required
Worn camshaft lobes Replace the camshaft and valve lifters.
Excessive oil pressure
A lubrication system with excessive oil pressure may lead to excessive
valve lifter pump-up and loss of compression.
1. Perform an oil pressure test. Refer to Oil Pressure Diagnosis and
Testing.
2. Repair or replace the oil pump, as required.
Faulty cylinder head gaskets and/or cracking or other damage to the
cylinder heads and engine block cooling system passages
Coolant consumption may or may not cause the engine to overheat.
1. Inspect for spark plugs saturated by coolant. Refer to Spark Plug
Inspection.
2. Perform a pressure test to the cooling system. Refer to Loss of
Coolant .
3. Inspect the cylinder heads, engine block, and/or head gaskets.
Refer to Coolant in Combustion Chamber .
4. Repair or replace, as required.
Worn piston rings
Oil consumption may or may not cause the engine to misfire
1. Inspect the spark plugs for oil deposits. Refer to Spark Plug
Inspection .
2. Inspect the cylinders for a loss of compression. Refer to Engine
Compression Test .
3. Perform cylinder leak down and compression testing to identify the
cause. Refer to Cylinder Leakage Test .
4. Repair or replace, as required.

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A damaged crankshaft reluctor wheel
A damaged crankshaft reluctor wheel can result in different symptoms,
depending on the severity and location of the damage.
• Systems with electronic communications, DIS, or coil per cylinder,
and SEVERE reluctor ring damage may exhibit periodic loss of crankshaft
position, stop delivering a signal, and then re-sync the crankshaft position.
• Systems with electronic communication, DIS, or coil per cylinder, and
SLIGHT reluctor ring damage may exhibit no loss of crankshaft position
and no misfire may occur. However, a DTC P0300 may be set.
• Systems with mechanical communications and SEVERE reluctor ring
damage may cause additional pulses and affect fuel and spark delivery to
the point of generating a DTC P0300 or DTC P0336.
Replace the sensor and/or crankshaft reluctor wheel, as required.
BASE ENGINE MISFIRE WITH ABNORMAL VALVE TRAIN NOISE
Cause Correction
Worn or loose rocker arms Repair or replace the valve rocker arms, as required.
Worn or bent push rods Replace the push rods.
Sticking valves
Carbon buildup on the valve stem and/or seat can cause the valve to not
close properly.
Repair or replace, as required.
Excessively worn or mis-aligned timing chain Repair or replace the timing chain, camshaft retainer, and sprockets,
as required
Worn camshaft lobes Replace the camshaft and valve lifters.
Sticking lifters Replace, as required.

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© 2006 WorkhorseCustom Chassis — All Rights Reserved
BASE ENGINE MISFIRE WITH COOLANT CONSUMPTION
Cause Correction
Faulty cylinder head gaskets and/or cracking or other damage to the
cylinder heads and engine block cooling system passages
Coolant consumption may or may not cause the engine to overheat.
1. Inspect for spark plugs saturated by coolant. Refer to Spark Plug
Inspection .
2. Perform a pressure test to the cooling system. Refer to Loss of
Coolant .
3. Perform a cylinder leak down test. Refer to Cylinder Leakage Test .
4. Inspect the cylinder heads and engine block for damage to the
coolant passages and/or a faulty head gasket. Refer to Coolant in
Combustion Chamber .
5. Repair or replace, as required.
BASE ENGINE MISFIRE WITH EXCESSIVE OIL CONSUMPTION
Cause Correction
Leaking intake gaskets Repair or replace the intake manifold bolts and/or gaskets, as
required.
Worn valves, valve guides and/or valve stem oil seals 1. Inspect the spark plugs for oil deposits. Refer to Spark Plug
Inspection .
2. Inspect the cylinders for loss of compression. Refer to Engine
Compression Test .
3. Repair or replace, as required.
Worn piston rings
Oil consumption may or may not cause the engine to misfire.
1. Inspect the spark plugs for oil deposits. Refer to Spark Plug
Inspection .
2. Inspect the cylinders for a loss of compression. Refer to Engine
Compression Test .
3. Perform cylinder leak down and compression testing to determine
the cause. Refer to Cylinder Leakage Test .
4. Repair or replace, as required.

WORKHORSE CUSTOM CHASSIS
Service Manual
W SeriesWCC
SECTION
6.2
PAGE
20 Engine Mechanical
W Series Chassis
TOC
© 2006 WorkhorseCustom Chassis — All Rights Reserved
ENGINE NOISE ON START-UP, BUT ONLY LASTING A FEW SECONDS
Cause Correction
Incorrect oil level
An oil level that is overfull causes aeration within the oil.
Add or remove oil, as required, to achieve the proper level.
Incorrect oil filter without anti-drainback feature Install the correct oil filter.
Incorrect oil viscosity 1. Drain the oil.
2. Install the correct viscosity oil.
High valve lifter leak down rate Replace the valve lifters, as required.
Worn crankshaft thrust bearing 1. Inspect the crankshaft end play.
2. Inspect the thrust bearing and crankshaft.
3. Repair or replace, as required.
Damaged or faulty oil filter bypass valve 1. Inspect the oil filter bypass valve for proper operation.
2. Repair or replace, as required.