Kohler Command PRO EFI User manual

ECH630-ECH749, CH735, CH26, CH745
Service Manual
KohlerEngines.com 124 690 01 Rev. S
2 Safety
3 Maintenance
5 Specifications
23 Tools and Aids
26 Troubleshooting
31 Air Cleaner/Intake
32 Electronic Fuel Injection (EFI) System-Electronic Throttle Body (ETB) ECH
65 Electronic Fuel Injection (EFI) System-ECH WITH OXYGEN SENSOR
94 Electronic Fuel Injection (EFI) System-ECH WITHOUT OXYGEN SENSOR
115 Electronic Fuel Injection (EFI) System-Bosch
148 Lubrication System
150 Electrical System
157 Starter System
161 Disassembly/Inspection and Service
182 Reassembly
IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating
instruction of equipment that this engine powers.
Ensure engine is stopped and level before performing any maintenance or service.

Safety
2 24 690 01 Rev. SKohlerEngines.com
SAFETY PRECAUTIONS
WARNING: A hazard that could result in death, serious injury, or substantial property damage.
CAUTION: A hazard that could result in minor personal injury or property damage.
NOTE: is used to notify people of important installation, operation, or maintenance information.
WARNING
Explosive Fuel can cause
fires and severe burns.
Do not fill fuel tank while
engine is hot or running.
Gasoline is extremely flammable
and its vapors can explode if
ignited. Store gasoline only in
approved containers, in well
ventilated, unoccupied buildings,
away from sparks or flames.
Spilled fuel could ignite if it comes
in contact with hot parts or sparks
from ignition. Never use gasoline
as a cleaning agent.
WARNING
Rotating Parts can cause
severe injury.
Stay away while engine
is in operation.
Keep hands, feet, hair, and
clothing away from all moving
parts to prevent injury. Never
operate engine with covers,
shrouds, or guards removed.
WARNING
Carbon Monoxide can
cause severe nausea,
fainting or death.
Avoid inhaling exhaust
fumes. Never run engine
indoors or in enclosed
spaces.
Engine exhaust gases contain
poisonous carbon monoxide.
Carbon monoxide is odorless,
colorless, and can cause death if
inhaled.
WARNING
Accidental Starts can
cause severe injury or
death.
Disconnect and ground
spark plug lead(s) before
servicing.
Before working on engine or
equipment, disable engine as
follows: 1) Disconnect spark plug
lead(s). 2) Disconnect negative (–)
battery cable from battery.
WARNING
Hot Parts can cause
severe burns.
Do not touch engine
while operating or just
after stopping.
Never operate engine with heat
shields or guards removed.
WARNING
Cleaning Solvents can
cause severe injury or
death.
Use only in well
ventilated areas away
from ignition sources.
Carburetor cleaners and solvents
are extremely flammable. Follow
cleaner manufacturer’s warnings
and instructions on its proper and
safe use. Never use gasoline as a
cleaning agent.
CAUTION
Electrical Shock can
cause injury.
Do not touch wires while
engine is running.
CAUTION
Damaging Crankshaft
and Flywheel can cause
personal injury.
Using improper procedures can
lead to broken fragments. Broken
fragments could be thrown from
engine. Always observe and use
precautions and procedures when
installing flywheel.
WARNING
High Pressure Fluids can
puncture skin and cause
severe injury or death.
Do not work on fuel
system without proper
training or safety
equipment.
Fluid puncture injuries are highly
toxic and hazardous. If an injury
occurs, seek immediate medical
attention.
WARNING
Explosive Fuel can
cause fires and severe
burns.
Fuel system ALWAYS
remains under HIGH
PRESSURE.
Wrap a shop towel completely
around fuel pump module
connector. Press release button(s)
and slowly pull connector away
from fuel pump module allowing
shop towel to absorb any residual
fuel in high pressure fuel line. Any
spilled fuel must be completely
wiped up immediately.

Maintenance
324 690 01 Rev. S KohlerEngines.com
MAINTENANCE INSTRUCTIONS
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair
establishment or individual; however, warranty repairs must be performed by a Kohler authorized dealer.
MAINTENANCE SCHEDULE
Every 25 Hours or Annually¹
●Service/replace low-profile precleaner (if equipped). Air Cleaner/Intake
Every 100 Hours or Annually¹
●Change oil. Lubrication System
●Replace low-profile air cleaner element. Air Cleaner/Intake
●Remove and clean shrouds and cooling areas. Inspect for any debris visible
through flywheel cooling holes (if equipped) and clean as necessary. Air Cleaner/Intake
●Check oil cooler fins, clean as necessary (if equipped). Lubrication System
Every 150 Hours
●Check heavy-duty filter minder. Air Cleaner/Intake
●Inspect heavy-duty air filter paper element and inlet screen area. Air Cleaner/Intake
Every 200 Hours¹
●Replace unique Electronic Fuel Injection (EFI) fuel filter.
Every 200 Hours
●Change oil filter. Lubrication System
Every 300 Hours¹
●Replace heavy-duty air cleaner element and check inner element. Air Cleaner/Intake
Every 300 Hours²
●Change oil and filter (KOHLER PRO 10W-50 oil and KOHLER PRO filter only). Lubrication System
Every 500 Hours or Annually¹
●Replace spark plugs and set gap. Electrical System
Every 600 Hours¹
●Replace heavy-duty air cleaner inner element. Air Cleaner/Intake
¹Perform these procedures more frequently under severe, dusty, dirty conditions.
²Option only if using KOHLER®PRO oil and PRO filter.
REPAIRS/SERVICE PARTS
Kohler genuine service parts can be purchased from Kohler authorized dealers. To find a local Kohler authorized
dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).

Maintenance
4 24 690 01 Rev. SKohlerEngines.com
OIL RECOMMENDATIONS
All-season KOHLER®PRO 10W-50 Synthetic Oil is the
ideal oil for KOHLER engines. It is specifically formulated
to extend the oil and oil filter change interval to 300
Hours when paired with a KOHLER PRO Extended Life
Oil Filter.
300-Hour oil and oil filter change intervals are exclusive
to and only authorized on KOHLER engines that utilize
both the KOHLER PRO 10W-50 Synthetic Oil and
KOHLER PRO Extended Life Oil Filter. Alternative
engine oils and oil filters may be used with KOHLER
engines but require 100-Hour oil and 200-Hour oil filter
change intervals for proper maintenance. Oil must be
API (American Petroleum Institute) service class SJ or
higher. Select viscosity based on air temperature at time
of operation as shown below.
°F -20 020324060
50 80 100
°C -30 -20 -10 0 10 20 30 40
5W-30
10W-30
SAE 30
Kohler PRO 10W-50
FUEL RECOMMENDATIONS
WARNING
Explosive Fuel can cause fires and severe
burns.
Do not fill fuel tank while engine is hot or
running.
Gasoline is extremely flammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or flames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
NOTE: E15, E20 and E85 are NOT approved and
should NOT be used; effects of old, stale or
contaminated fuel are not warrantable.
Fuel must meet these requirements:
●Clean, fresh, unleaded gasoline.
●Octane rating of 87 (R+M)/2 or higher.
●Research Octane Number (RON) 90 octane minimum.
●Gasoline up to 10% ethyl alcohol, 90% unleaded is
acceptable.
●Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blend (max 15% MTBE by volume) are
approved.
●Do not add oil to gasoline.
●Do not overfill fuel tank.
●Do not use gasoline older than 30 days.
STORAGE
If engine will be out of service for 2 months or more
follow procedure below.
1. Add Kohler PRO Series fuel treatment or equivalent
to fuel tank. Run engine 2-3 minutes to get stabilized
fuel into fuel system (failures due to untreated fuel
are not warrantable).
2. Change oil while engine is still warm from operation
(Not required if using KOHLER PRO 10W-50
full-synthetic oil). Remove spark plug(s) and pour
about 1 oz. of engine oil into cylinder(s). Replace
spark plug(s) and crank engine slowly to distribute
oil.
3. Disconnect negative (-) battery cable.
4. Store engine in a clean, dry place.

Specifications
524 690 01 Rev. S KohlerEngines.com
Engine Dimensions with Heavy-Duty Air Cleaner-Flywheel Side
AValve Cover B451.16 mm (17.762 in.) CFuel Pump D342.52 mm
(13.485 in.)
E230.20 mm (9.063 in.) F130.0 mm (5.118 in.) G88.28 mm
(3.475 in.) H298.93 mm (11.769 in.)
I277.22 mm (10.914 in.) J135.0 mm (5.315 in.) K
77.17 mm
(3.038 in.) Spark Plug
Removal
L
67.19 mm
(2.645 in.) Spark
Plug Boot Removal
M
37.15 mm
(1.463 in.) Spark Plug
Boot
N
320.89 mm
(12.633 in.) Spark Plug
Removal
O
315.14 mm
(12.407 in.) Spark
Plug Boot Removal
P20°
QEngine Mounting
Surface R4X Ø 10.3 mm (0.406 in.) S184.20 mm (7.252 in.) TEngine Center Line
U92.10 mm (3.626 in.) VCenter Line Mounting
Hole "A" W134.80 mm (5.307 in.) X
15.70 mm
(0.618 in.) Oil Filter
Removal
YCrankshaft Center Line Z
315.25 mm
(12.412 in.) Spark Plug
Boot Removal
AA 4.12 mm (0.182 in.)
Spark Plug Boot AB
25.46 mm
(1.002 in.) Spark
Plug Boot Removal
AC Fuel Filter AD 39.66 mm (1.562 in.)
Spark Plug Removal AE Fuel Pump
F
E
G
H
I
K
L
N
O
M
P
Q
R
S
T
A
B
D
C
J
U
V
X
W
N
Y
Z
AD
AA
AB
AC
P
AE

Specifications
6 24 690 01 Rev. SKohlerEngines.com
A
B
C
D
E
F
G
H
I
J
K
L
MN
O
PR
Q
S
V
T
U
WX
Y
A371.44 mm
(14.624 in.) B209.88 mm (8.263 in.) C52.43 mm (2.064 in.) D
30.0 mm (1.181 in.)
Spark Plug Center
Line
E32.00 mm (1.260 in.)
Exhaust Port #2 FOil Fill GDipstick H101.38 mm (3.992 in.)
I85.50 mm (3.366 in.)
Keyway J1/4 in. Square Keyway K622.70 mm (24.516 in.) L
7/16-20 UNF-2B in.
38.10 mm (1.5 in.)
Deep
M155.58 mm (6.125 in.) N152.08 mm (5.987 in.)
Oil Filter OEngine Mounting Surface P4.00 mm (0.157 in.) Pilot
Q52.75 mm (2.077 in.)
Oil Filter RCenter Line Mounting Hole "A" S100.0 mm (3.937 in.) T89.0 mm (3.504 in.)
U51.0 mm (2.008 in.) VOil Drain Plug
3/8 in. NPT W12.28 mm (0.483 in.) XRectifier-Regulator
YFuel Pump
Engine Dimensions with Heavy-Duty Air Cleaner-Oil Filter Side

Specifications
724 690 01 Rev. S KohlerEngines.com
Engine Dimensions with Heavy-Duty Air Cleaner-PTO Side
B
A
C
E
F
D
G
H
I
J
L
K
M
N
PO
Q
S
R
U
T
V
G
A335.04 mm (13.19 in.) B122.10 mm (4.807 in.) C65.0 mm (2.559 in.)
Muffler Mounting D75.42 mm (2.969 in.)
ELift Strap FOil Fill Location G30° H50.00 mm (1.969 in.)
Exhaust Port #2
I2 X 306.24 mm
(12.136 in.) J
2 X M8 X 1.25
20.5 mm
(0.807 in.) Deep
K135° L
5/16-24 UNC-2B in.
17 mm (0.669 in.)
Deep
127 mm (5.0 in.)
B.C.
M
3/8-16 UNC-2B in.
21 mm (0.827 in.)
Deep
165.1 mm (6.5 in.)
B.C.
N
7/16-14 UNC-2B in.
21 mm (0.827 in.)
Deep 196.8 mm
(7.75 in.) B.C.
OCenter Line Mounting
Hole "A" P177.8 mm (7.0 in.) Pilot Diameter
QEngine Mounting
Surface RSolenoid Shift Starter S283.58 mm (11.164 in.) Muffler Mounting T50.00 mm (1.969 in.) Exhaust Port #1
UM8 X 1.25 4 Studs V45°
GG

Specifications
8 24 690 01 Rev. SKohlerEngines.com
Engine Dimensions with Heavy-Duty Air Cleaner-Starter Side
A
B
C
D
E
GF
H
I
J
K
L
A
50.0 mm (1.969 in.)
Center Line Spark
Plug
B12.0 mm (0.472 in.)
Exhaust Port #1 C
67.50 mm (2.657 in.)
Muffler Mounting
Bosses
DDipstick
E432.58 mm
(17.031 in.) FEngine Mounting Surface GCenter Line Mounting Hole "A" H89.0 mm (3.504 in.)
I51.0 mm (2.008 in.) JOil Drain Plug 3/8 in. K12.28 mm (0.483 in.) LLift Strap

Specifications
924 690 01 Rev. S KohlerEngines.com
Engine Dimensions with Low-Profile Air Cleaner-Flywheel Side
F
E
G
H
I
K
L
N
O
M
P
Q
R
S
T
A
B
D
C
J
U
V
X
WY
ZAA
J
I
A451.16 mm (17.762 in.) B298.93 mm (11.769 in.) CValve Cover D12.95 mm (0.510 in.)
E
67.19 mm
(2.645 in.) Spark
Plug Boot Removal
F
77.17 mm
(3.038 in.) Spark
Plug Removal
G
37.15 mm
(1.463 in.) Spark
Plug Boot
H473.43 mm
(18.639 in.)
I
320.89 mm
(3.038 in.) Spark
Plug Removal
J20° K
315.14 mm
(12.407 in.) Spark
Plug Boot Removal
LEngine Mounting
Surface
M4X Ø 10.3 mm
(0.406 in.) N184.20 mm (7.252 in.) OEngine Center Line P92.10 mm (3.628 in.)
QCenter Line Mounting
Hole "A" R134.80 mm (5.307 in.) S
15.70 mm
(0.618 in.) Oil Filter
Removal
TCrankshaft Center
Line
U
315.25 mm
(12.412 in.) Spark Plug
Boot Removal
VFuel Filter W4.12 mm (0.162 in.)
Spark Plug Boot X
29.58 mm
(1.165 in.) Spark
Plug Boot Removal
Y
60.0 mm (2.362 in.) Air
Cleaner Cover
Removal
Z39.66 mm (1.562 in.)
Spark Plug Removal AA Fuel Pump

Specifications
10 24 690 01 Rev. SKohlerEngines.com
Engine Dimensions with Low-Profile Air Cleaner-Oil Filter Side
A
BC
D
E
F
GH
I
J K
L
M
N
O
P
R
Q
S
V
T
U
A371.44 mm
(14.624 in.) B
30.0 mm (1.181 in.)
Spark Plug Center
Line
CFuel Pump DOil Fill
EDipstick F101.38 mm (3.992 in.) G85.50 mm (3.366 in.)
Keyway H1/4 in. Square Keyway
I
7/16-20 UNF 2B in.
38.10 mm (1.5 in.)
Deep
J155.58 mm (6.125 in.) K152.08 mm (5.987 in.)
Oil Filter LEngine Mounting Surface
MMounting Surface N4.00 mm (0.157 in.)
Pilot OCenter Line Mounting Hole "A" P100.0 mm (3.937 in.)
Q52.75 mm (2.077 in.)
Oil Filter R51.0 mm (2.008 in.) S89.0 mm (3.504 in.) TOil Drain Plug 3/8 in. NPT
U12.28 mm (0.483 in.) VRectifier-Regulator

Specifications
1124 690 01 Rev. S KohlerEngines.com
Engine Dimensions with Low-Profile Air Cleaner-PTO Side
B
A
C
E
F
D
G
H
I
J
L
K
M
N
PO
Q
S
R
U
T
V
G
G
G
A335.04 mm (13.19 in.) B122.10 mm (4.807 in.) C65.0 mm (2.559 in.)
Muffler Mounting D75.42 mm (2.969 in.)
ELift Strap FOil Fill Location G30° H50.00 mm (1.969 in.)
Exhaust Port #2
I2 X 308.24 mm
(12.136 in.) J
2 X M8 X 1.25
20.5 mm
(0.807 in.) Deep
K135° L
5/16-24 UNC-2B in.
17 mm (0.669 in.)
Deep
127 mm (5.0 in.)
B.C.
M
3/8-16 UNC-2B in.
21 mm (0.827 in.)
Deep
165.1 mm (6.5 in.)
B.C.
N
7/16-14 UNC-2B in.
21 mm (0.827 in.)
Deep 196.8 mm
(7.75 in.) B.C.
OCenter Line Mounting
Hole "A" P177.8 mm (7.0 in.) Pilot Diameter
QEngine Mounting
Surface RSolenoid Shift Starter S283.58 mm (11.164 in.) Muffler Mounting T50.00 mm (1.969 in.) Exhaust Port #1
UM8 X 1.25 4 Studs V45°

Specifications
12 24 690 01 Rev. SKohlerEngines.com
Engine Dimensions with Low-Profile Air Cleaner-Starter Side
A
B
C
D
E
G
F
H
I
J
K
L
M
A
50.0 mm (1.969 in.)
Center Line Spark
Plug
B12.0 mm (0.472 in.)
Exhaust Port #1 C32.0 mm (1.260 in.) Exhaust Port #2 DDipstick
E432.58 mm
(17.031 in.) FEngine Mounting Surface G
67.50 mm (2.657 in.)
Muffler Mounting
Bosses
HCenter Line Mounting
Hole "A"
I89.0 mm (3.504 in.) J51.0 mm (2.008 in.) KOil Drain Plug 3/8 in.
NPT L12.28 mm (0.483 in.)
MLift Strap

Specifications
1324 690 01 Rev. S KohlerEngines.com
ENGINE IDENTIFICATION NUMBERS
Kohler engine identification numbers (model, specification and serial) should be referenced for efficient repair,
ordering correct parts, and engine replacement.
Model. . . . . . . . . . . . . . . . . . . . . ECH630
EFI Command Engine
Horizontal Shaft
Numerical Designation
Specification . . . . . . . . . . . . . . . ECH630-3001
Serial . . . . . . . . . . . . . . . . . . . . . 5123500328
Year Manufactured Code Factory Code
Code Year
51 2021
52 2022
53 2023
GENERAL SPECIFICATIONS3,6 ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Bore 80 mm (3.15 in.) 83 mm (3.27 in.) 83 mm (3.27 in.)
Stroke 69 mm (2.72 in.) 67 mm (2.64 in.)
Displacement 694 cc (42.4 cu. in.) 747 cc (45.6 cu. in.) 725 cc (44 cu. in.)
Oil Capacity (refill) 1.9 L (2.0 U.S. qt.)
Maximum Angle of Operation
(@ full oil level)425°
TORQUE SPECIFICATIONS3,5 ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Blower Housing
Into cored aluminum hole or weld nut
M5
M6
Into extruded hole in sheet metal
M5
M6
6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Closure Plate
Fastener 25.6 N·m (227 in. lb.) 24.4 N·m (216 in. lb.)
Connecting Rod
Cap Fastener (torque in increments)
8 mm straight shank
8 mm step-down
6 mm straight shank
Black Coating
Gray Metallic Coating
11.6 N·m (103 in. lb.)
13.6 N·m (120 in. lb.)
22.7 N·m (200 in. lb.)
14.7 N·m (130 in. lb.)
11.3 N·m (100 in. lb.)
13.6 N·m (120 in. lb.)
3 Values are in Metric units. Values in parentheses are English equivalents.
4Exceeding maximum angle of operation may cause engine damage from insufficient lubrication.
5Lubricate threads with engine oil prior to assembly.
6Any and all horsepower (hp) references by Kohler are Certified Power Ratings and per SAE J1940 & J1995 hp
standards. Details on Certified Power Ratings can be found at KohlerEngines.com.

Specifications
14 24 690 01 Rev. SKohlerEngines.com
TORQUE SPECIFICATIONS3,5 ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Crankcase
Breather Cover Fastener 11.3 N·m (100 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Engine Temperature Sensor (into
breather cover)
7.3 N·m (65 in. lb.)
Oil SentryTM (into breather cover) 4.5 N·m (40 in. lb.)
Oil Drain Plug 13.6 N·m (10 ft . lb.)
Cylinder Head
Hex Flange Nut (torque in 2
increments)
Head Bolt (torque in 2 increments)
first to 16.9 N·m (150 in. lb.)
finally to 33.9 N·m (300 in. lb.)
first to 22.6 N·m (200 in. lb.)
finally to 41.8 N·m (370 in. lb.)
Rocker Arm Screw
Black Screw (M6x1.0x34)
Silver Screw (M6x1.0x45)
18.1 N·m (160 in. lb.)
11.9 N·m (105 in. lb.)
ETB Cover (LPAC)
Fastener 5.6 N·m (50 in. lb.)
Fan/Flywheel
Fan Fastener 9.9 N·m (88 in. lb.)
Flywheel Retaining Screw 71.6 N·m (52.8 ft . lb.) 66.4 N·m (49 ft. lb.)
Metal Debris Screen Fastener (to
flywheel)
9.9 N·m (88 in. lb.)
Plastic Debris Screen Fastener (to fan) 4.0 N·m (35 in. lb.)
Fuel Pump
Module Baffle Fastener 11.9 N·m (105 in. lb.)
Module Fastener 9.2 N·m (81 in. lb.)
Pulse Pump Bracket Fastener 2.1 N·m (25 in. lb.)
Pulse Pump Fastener to Bracket 7.3 N·m (68 in. lb.) into new holes
6.2 N·m (55 in. lb.) into used holes
Governor (if equipped)
Lever Nut 7.1 N·m (63 in. lb.) 6.8 N·m (60 in. lb.)
Speed Control Assembly
Assembled to Cylinder Heads
Assembled to Blower Housing
10.7 N·m (95 in. lb.)
2.8 N·m (25 in. lb.)
Ignition
Spark Plug 27 N·m (20 ft. lb.)
Coil Fastener 10.2 N·m (90 in. lb.)
Ignition Module Fastener Torque 4.0-6.2 N·m (35-55 in. lb.)
Electronic Control Unit Screw 6.2 N·m (55 in. lb.)
Rectifier-Regulator Ground Strap/
Ground Lead Fastener (into backing
plate) (Standard Charging System)
2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
Rectifier-Regulator Ground Lead
Fastener to Ground Lug/Backing Plate
(Standard Charging System)
5.6 N·m (50 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
3 Values are in Metric units. Values in parentheses are English equivalents.
5Lubricate threads with engine oil prior to assembly.

Specifications
1524 690 01 Rev. S KohlerEngines.com
TORQUE SPECIFICATIONS3,5 ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Ignition (continued)
Rectifier-Regulator Fastener (Standard
Charging System)
1.4 N·m (12.6 in. lb.)
Rectifier-Regulator Power Studs/Nuts
(High Output Charging System)
4.0 N·m (35 in. lb.)
Rectifier-Regulator Terminal Block
Cover Fastener (High Output Charging
System)
2.8 N·m (25 in. lb.)
Rectifier-Regulator to Bracket Fastener
(High Output Charging System)
8.3 N·m (73 in. lb.)
High Output Charging Fuse Cover/
Bracket Fastener
8.3 N·m (73 in. lb.)
Rectifier-Regulator Bracket to Cylinder
Head Fastener (High Output Charging
System)
12.5 N·m (110 in. lb.)
Crankshaft Position Sensor
Earlier Design Bracket
Crankshaft Position Sensor to Bracket
Screw 11.3 N·m (100 in. lb.)
Crankshaft Position Sensor Bracket to
Crankcase Screw 8.3 N·m (73 in. lb.)
Crankshaft Position Sensor
Later Design Bracket
Crankshaft Position Sensor to Bracket
Screw 6.8 N·m (60 in. lb.)
Crankshaft Position Sensor Bracket to
Crankcase Screw 7.3 N·m (65 in. lb.)
Intake Manifold
Fastener (torque in 2 increments) first to 7.8 N·m (69 in. lb.)
finally to 10.5 N·m (93 in. lb.)
first to 7.4 N·m (66 in. lb.)
finally to 9.9 N·m (88 in. lb.)
Manifold Absolute Pressure (MAP)
Sensor Fastener (Engines with
Separate MAP and Intake Air
Temperature Sensors)
7.3 N·m (65 in. lb.)
Temperature/Manifold Absolute
Pressure (TMAP) Sensor Fastener
(Engines with Combined Sensor)
7.3 N·m (65 in. lb.)
Air Cleaner to Throttle Body Fastener
Nut
8.3 N·m (73 in. lb.)
Heavy-Duty Air Cleaner Mounting
Bracket Fastener
5.8 N·m (51 in. lb.)
Fuel Injector Cap Fastener 7.3 N·m (65 in. lb.)
3 Values are in Metric units. Values in parentheses are English equivalents.
5Lubricate threads with engine oil prior to assembly.

Specifications
16 24 690 01 Rev. SKohlerEngines.com
TORQUE SPECIFICATIONS3,5 ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Muffler
Retaining Nut 27.8 N·m (246 in. lb.) 24.4 N·m (216 in. lb.)
Oxygen Sensor smaller 14 mm
(9/16 in.) wrench size
18 N·m (159 in. lb.)
Oxygen Sensor larger 22 mm (7/8 in.)
wrench size
50.1 N·m (37 ft . lb.)
Oil Cooler
Oil Cooler/Adapter Nipple 28.5 N·m (21 ft . lb.) 27 N·m (20 ft. lb.)
Fastener
Into Blower Housing
Between Oil Cooler Hoses
2.8 N·m (25 in. lb.)
2.3 N·m (20 in. lb.)
Speed Control Bracket (if equipped)
Fastener Assembled to Cylinder Heads 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Fastener Assembled to Blower Housing 2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
Fastener Torque 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Starter Assembly
Thru Bolt
Nippondenso (Solenoid Shift)
Delco-Remy (Solenoid Shift)
5.6-9.0 N·m (49-79 in. lb.)
4.5-7.5 N·m (40-84 in. lb.)
5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw 16.0 N·m (142 in. lb.) 15.3 N·m (135 in. lb.)
Brush Holder Mounting Screw
Delco-Remy Starter
2.5-3.3 N·m (22-29 in. lb.)
2.5-3.3 N·m (22-29 in. lb.)
Starter Solenoid
Mounting Hardware
Nippondenso Starter
Delco-Remy Starter
4.0-6.0 N·m (35-53 in. lb.)
6.0-9.0 N·m (53-79 in. lb.)
4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead
Nippondenso Starter
Delco-Remy Starter
8.0-11.0 N·m (71-97 in. lb.)
8.0-12.0 N·m (71-106 in. lb.)
8.0-11.0 N·m (71-97 in. lb.)
Stator
Mounting Screw 9.3 N·m (82 in. lb.)
Valve Cover
Fastener
Gasket Style Cover
Black O-Ring Style Cover
w/Shoulder Screws
w/Flange Screws and Spacers
Yellow or Brown O-Ring Style
Cover w/Integral Metal Spacers
9.0 N·m (80 in. lb.)
3.4 N·m (30 in. lb.)
5.6 N·m (50 in. lb.)
9.9 N·m (88 in. lb.)
9.0 N·m (80 in. lb.)
3 Values are in Metric units. Values in parentheses are English equivalents.
5Lubricate threads with engine oil prior to assembly.

Specifications
1724 690 01 Rev. S KohlerEngines.com
CLEARANCE
SPECIFICATIONS3ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Camshaft
End Play (with shim) 0.101/0.406 mm (0.0040/0.0160 in.) 0.076/0.127 mm (0.0030/0.0050 in.)
Running Clearance 0.025/0.105 mm (0.001/0.004 in.) 0.025/0.063 mm (0.0010/0.0025 in.)
Bore I.D.
New
Max. Wear Limit
20.000/20.025 mm (0.7874/0.7884 in.)
20.038 mm (0.7889 in.)
20.000/20.025 mm (0.7874/0.7884 in.)
20.038 mm (0.7889 in.)
Bearing Surface O.D.
New
Max. Wear Limit
19.920/19.975 mm (0.7843/0.7864 in.)
19.914 mm (0.7840 in.)
19.962/19.975 mm (0.7859/0.7864 in.)
19.959 mm (0.7858 in.)
Connecting Rod
Connecting Rod-to-Crankpin
Running Clearance @ 21°C
(70°F)
New
Max. Wear Limit
0.043/0.073 mm (0.0017/0.0029 in.)
0.088 mm (0.0035 in.)
0.030/0.055 mm (0.0012/0.0022 in.)
0.070 mm (0.0028 in.)
Connecting Rod-to-Crankpin
Side Clearance 0.26/0.63 mm (0.0102/0.0248 in.) 0.26/0.63 mm (0.0102/0.0248 in.)
Connecting Rod-to-Piston Pin
Running Clearance @ 21°C
(70°F)
0.015/0.028 mm (0.0006/0.0011 in.) 0.015/0.028 mm (0.0006/0.0011 in.)
Piston Pin End I.D. @ 21°C
(70°F)
New
Max. Wear Limit
17.015/17.023 mm (0.6699/0.6702 in.)
17.036 mm (0.6707 in.)
17.015/17.023 mm (0.6699/0.6702 in.)
17.036 mm (0.6707 in.)
Crankcase
Governor Cross Shaft Bore I.D.
New
Max. Wear Limit
6 mm Shaft
New
Max. Wear Limit
8 mm Shaft
New
Max. Wear Limit
8.025/8.075 mm (0.3159/0.3179 in.)
8.088 mm (0.3184 in.)
6.025/6.050 mm (0.2372/0.2382 in.)
6.063 mm (0.2387 in.)
8.025/8.075 mm (0.3159/0.3179 in.)
8.088 mm (0.3184 in.)
Crankshaft
End Play (free) 0.070/0.590 mm (0.0028/0.0230 in.) 0.070/0.590 mm (0.0028/0.0230 in.)
End Play (w/thrust bearing
components) 0.070/1.190 mm (0.0028/0.0468 in.) 0.070/1.190 mm (0.0028/0.0468 in.)
Bore (in crankcase)
New
Max. Wear Limit
40.972/40.997 mm (1.6131/1.6141 in.)
41.011 mm (1.6146 in.)
40.965/41.003 mm (1.6128/1.6143 in.)
41.016 mm (1.6148 in.)
Bore (in closure plate)
New 40.974/41.000 mm (1.6131/1.6141 in.) 40.987/40.974 mm (1.6136/1.6131 in.)
Crankshaft to Sleeve Bearing
(closure plate) Running
Clearance
New 0.03/0.12 mm (0.001/0.005 in.) 0.03/0.09 mm (0.0012/0.0035 in.)
3 Values are in Metric units. Values in parentheses are English equivalents.

Specifications
18 24 690 01 Rev. SKohlerEngines.com
CLEARANCE
SPECIFICATIONS3ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Crankshaft (continued)
Crankshaft Bore (In Closure
Plate)-to-Crankshaft Running
Clearance
New 0.039/0.087 mm (0.0015/0.0034 in.) 0.039/0.074 mm (0.0015/0.0029 in.)
Flywheel End Main Bearing
Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper Limit
Max. Out-of-Round Limit
40.913/40.935 mm (1.6107/1.6116 in.)
40.843 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
40.913/40.935 mm (1.6107/1.6116 in.)
40.84 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Closure Plate End Main Bearing
Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper Limit
Max. Out-of-Round Limit
40.913/40.935 mm (1.6107/1.6116 in.)
40.843 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
40.913/40.935 mm (1.6107/1.6116 in.)
40.84 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Connecting Rod Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper Limit
Max. Out-of-Round Limit
35.950/35.973 mm (1.4153/1.4163 in.)
35.941 mm (1.415 in.)
0.018 mm (0.0007 in.)
0.025 mm (0.0010 in.)
35.955/35.973 mm (1.4156/1.4163 in.)
35.94 mm (1.415 in.)
0.018 mm (0.0007 in.)
0.025 mm (0.0010 in.)
Crankshaft T.I.R.
PTO End, Crank in Engine
Entire Crank, in V-Blocks
0.279 mm (0.0110 in.)
0.10 mm (0.0039 in.)
0.279 mm (0.0110 in.)
0.10 mm (0.0039 in.)
Cylinder Bore
Bore I.D.
New 80.000/80.025 mm
(3.1496/3.2689 in.)
83.006/83.031 mm
(3.2680/3.2689 in.)
82.988/83.013 mm (3.2672/3.2682 in.)
O.D. - Max. Wear Limit 80.075 mm
(3.1526 in.)
83.081 mm (3.2709
in.)
83.051 mm (3.2697 in.)
Max. Out-of-Round Limit 0.120 mm (0.0047 in.) 0.12 mm (0.0047 in.)
Max. Taper 0.05 mm (0.0020 in.) 0.05 mm (0.0020 in.)
Cylinder Head
Max. Out-of-Flatness 0.076 mm (0.003 in.) 0.076 mm (0.003 in.)
3 Values are in Metric units. Values in parentheses are English equivalents.

Specifications
1924 690 01 Rev. S KohlerEngines.com
CLEARANCE
SPECIFICATIONS3ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Governor (if equipped)
Governor Cross Shaft -to-
Crankcase Running Clearance
6 mm Shaft
8 mm Shaft
0.025/0.126 mm (0.0009/0.0049 in.)
0.013/0.075 mm (0.0005/0.0030 in.)
0.025/0.126 mm (0.0009/0.0049 in.)
Cross Shaft O.D.
New
Max. Wear Limit
6 mm Shaft
New
Max. Wear Limit
8 mm Shaft
New
Max. Wear Limit
7.949/8.000 mm (0.3129/0.3149 in.)
7.936 mm (0.3124 in.)
5.975/6.012 mm (0.2352/0.2367 in.)
5.962 mm (0.2347 in.)
7.949/8.000 mm (0.3129/0.3149 in.)
7.936 mm (0.3124 in.)
Governor Gear Shaft -to-
Governor Gear Running
Clearance 0.090/0.160 mm (0.0035/0.0063 in.) 0.015/0.140 mm (0.0006/0.0055 in.)
Gear Shaft O.D.
New
Max. Wear Limit
5.990/6.000 mm (0.2358/0.2362 in.)
5.977 mm (0.2353 in.)
Ignition
Spark Plug Gap 0.76 mm (0.030 in.)
Crankshaft Position Sensor Air
Gap (only on earlier design
sensor bracket)
0.2-0.7 mm (0.008-0.027 in.)
Crankshaft Position Sensor
Max. Air Gap (only on later
design sensor bracket)
2.794 mm (0.110 in.)
Piston, Piston Rings, and Piston Pin
Piston Style A
Piston-to-Piston Pin Running
Clearance 0.006/0.017 mm (0.0002/0.0007 in.)
Pin Bore I.D.
New
Max. Wear Limit
17.006/17.012 mm (0.6695/0.6698 in.)
17.025 mm (0.6703 in.)
Pin O.D.
New
Max. Wear Limit
16.995/17.000 mm (0.6691/0.6693 in.)
16.994 mm (0.6691 in.)
Top Compression Ring-to-
Groove Side Clearance 0.050/0.095 mm (0.0019/0.0037 in.) 0.025/0.048 mm (0.0010/0.0019 in.)
Middle Compression Ring-to-
Groove Side Clearance 0.030/0.075 mm (0.0012/0.00307 in.) 0.015/0.037 mm (0.0006/0.0015 in.)
Oil Control Ring-to-Groove Side
Clearance 0.010/0.011 mm (0.0004/0.0043 in.) 0.026/0.176 mm (0.0010/0.0070 in.)
Top and Center Compression
Ring End Gap
New Bore 0.25/0.56 mm (0.0100/0.0224 in.)
Used Bore (Max.) 0.80 mm (0.0315 in.) 0.94 mm (0.037 in.)
3 Values are in Metric units. Values in parentheses are English equivalents.

Specifications
20 24 690 01 Rev. SKohlerEngines.com
CLEARANCE
SPECIFICATIONS3ECH630-ECH680 ECH730-ECH749 CH26 CH735 CH745
Piston Style A (continued)
Thrust Face O.D.779.943/79.961 mm
(3.1473/3.1480 in.)
82.949/82.967 mm (3.2657/3.2664 in.)
Max. Wear Limit 79.816 mm
(3.1423 in.)
82.822 mm (3.2606 in.)
Piston Thrust Face-to Cylinder
Bore7Running Clearance
New 0.039/0.082 mm (0.0015/0.0032 in.)
Piston Style B
Piston-to-Piston Pin Running
Clearance 0.006/0.017 mm (0.0002/0.0007 in.)
Pin Bore I.D.
New
Max. Wear Limit
17.006/17.012 mm (0.6695/0.6698 in.)
17.025 mm (0.6703 in.)
Pin O.D.
New
Max. Wear Limit
16.995/17.000 mm (0.6691/0.6693 in.)
16.994 mm (0.6691 in.)
Top Compression Ring-to-
Groove Side Clearance 0.030/0.070 mm (0.001/0.0026 in.)
Middle Compression Ring-to-
Groove Side Clearance 0.030/0.070 mm (0.001/0.0026 in.)
Oil Control Ring-to-Groove Side
Clearance 0.060/0.190 mm (0.0022/0.0073 in.)
Top Compression Ring End Gap
New Bore
0.100/0.279 mm
(0.0039/0.0110 in.) 0.189/0.277 mm (0.0074/0.0109 in.)
Used Bore (Max.) 0.490 mm
(0.0192 in.)
0.531 mm (0.0209 in.)
Middle Compression Ring End
Gap
New Bore
1.400/1.679 mm
(0.0551/0.0661 in.) 1.519/1.797 mm (0.0598/0.0708 in.)
Used Bore (Max) 1.941 mm
(0.0764 in.)
2.051 mm (0.0808 in.)
Thrust Face O.D.
New 79.966 mm
(3.1483 in.)8
82.978 mm (3.2668 in.)7
Max. Wear Limit 79.821 mm
(3.1426 in.)8
82.833 mm (3.2611 in.)7
Piston Thrust Face-to Cylinder
Bore Running Clearance
New
0.025/0.068 mm
(0.0010/0.0027 in.)80.019/0.062 mm (0.0007/0.0024 in.)7
3 Values are in Metric units. Values in parentheses are English equivalents.
7 Measure 6 mm (0.2362 in.) above bottom of piston skirt at right angles to piston pin.
8 Measure 13 mm (0.5118 in.) above bottom of piston skirt at right angles to piston pin.