Yamaha DE-DHT User manual

070030
ESTERN DRIVE
SERVICE MANUAL
DE-DHT
6U5-28197-ZJ-11

NOTICE
This manual has been prepared by Yamaha primarily for use by Yamaha dealers and their
trained mechanics when performing maintenance procedures and repairs to Yamaha equip-
ment. It has been written to suit the needs of persons who have a basic understanding of the
mechanical and electrical concepts and procedures inherent in the work, for without such
knowledge attempted repairs or service to the equipment could render it unsafe or unfit for
use.
Because Yamaha has a policy of continuously improving its products, models may differ in
detail from the descriptions and illustrations given in this publication. Use only the latest edi-
tion of this manual. Authorized Yamaha dealers are notified periodically of modifications and
significant changes in specifications and procedures, and these are incorporated in succes-
sive editions of this manual.
STERN DRIVE
SERVICE MANUAL
© 2006 by Yamaha Motor Co., Ltd.
1st Edition, August 2006
All rights reserved. Any reprinting or
unauthorized use without the written
permission of Yamaha Motor Co., Ltd.
is expressly prohibited.
Printed in Japan.

HOW TO USE THIS MANUAL
MANUAL FORMAT
This manual provides the mechanic with descriptions of the operations of disassembly, repair,
assembly and inspection, each of which is presented in a sequential, step-by-step procedure.
To assist you in finding your way around this manual, the section title and major heading is
given at the head of each page.
A table of contents is provided on the first page of each section.
ILLUSTRATIONS
Some illustrations in this manual may differ from the model you have. This is because a proce-
dure described may relate to several models, though only one is illustrated. (The name of the
model described will be mentioned in the description).
To help you identify components and understand the correct procedures of disassembly and
assembly, exploded diagrams are provided. Steps in the procedure are numbered: 1), 2), 3).
Parts shown in the illustrations are identified as: 1, 2, 3.
REFERENCES
These have been kept to a minimum. References to other sections of the manual include the
relevant page number.
WARNINGS, CAUTIONS AND NOTES
Attention is drawn to the various warnings, cautions and notes that distinguish important
information in this manual in the following ways.
⁄The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR SAFETY IS INVOLVED!
¡¡
¡¡
¡WARNING
Failure to follow WARNING instructions could result in severe injury or death to the marine
vehicle operator, a bystander, or a person inspecting or repairing the Stern Drive.
CAUTION:
A CAUTION indicates special precautions that must be taken to avoid damage to the Stern
Drive.
NOTE:
A NOTE provides key information to make procedures easier or clearer.

CONSTRUCTION OF THIS MANUAL
This manual consists of chapters for the main categories of subjects. (See “Symbols” on the
next page.)
1st title 1: This is a chapter with its symbol on the upper right of each page.
2nd title 2: This title appears on the top of the each page, to the left of the chapter symbol.
3rd title 3: This title precedes the paragraphs describing the working procedure.
All the procedures in this manual are organized in a sequential, step-by-step order. The infor-
mation has been compiled to provide the mechanic with an easy-to-read, handy reference that
contains comprehensive explanations of all disassembly, check, repair, and assembly proce-
dures.
Important procedures including removing, checking, and assembling steps 4are explained in
detail.
IMPORTANT FEATURES
¡Important engine data and information about special tools framed in a box together with
an illustrative symbol 5.
¡A circled numeral 6indicates a part name. A circled lower case letter indicates data or an
alignment mark 7.
¡An arrow 8indicates the course of action required to remedy the started condition of a
component.
EXPLODED DIAGRAM
Each chapter begins with exploded diagrams which facilitate correct disassembly and assem-
bly.
SHIM SELECTION (UPPER UNIT HOUSING)
R-gear Shim (T5) Adjustment
1. Use the guide, bearing puller 2 1and
the bearing puller 2to remove the bear-
ing outer race from the selector valve
housing.
NOTE:
¡When the bearing and the selector valve
housing are not replaced, DO NOT re-
move the bearing outer race.
¡When replacing the bearing, replace the
total inner and outer set.
¡Make sure that the bearing puller is set at
the position specified in the illustration.
Guide, bearing puller 2:
6U4-30-3
Bearing puller:
6U4-35
1
2
E
UPPER
UNIT
Drive shaft motive torque (A):
0.4 – 1.5 N·m
3. Loosen the front bearing housing bolts
to 1/2 rotation and measure pre-load B
(motive torque) of the drive shaft.
NOTE:
Measure resistance of the clutch disk section
as the pre-load B (motive torque).
4. Calculate the drive shaft pre-load (mo-
tive torque) based on the pre-load (mo-
tive torque) A and B.
Formula:
Drive shaft pre-load = pre-load (A) –pre-
load (B)
NOTE:
If the drive shaft pre-load (motive torque) is
greater than the specification, reduce the
shim T6b. If the drive shaft pre-load (motive
torque) is less than the specification, increase
the shim T6b.
4-27
T.R
Clamp screw:
3 N·m
BELLOWS AND HOSE INSPEC-
TION
1. Inspect:
¡Shift cable bellows 1
¡Exhaust bellows 2
¡Universal joint bellows 3
Cracks/Weathering/Damage →Re-
place.
Loose clamps 4→Tighten.
Refer to “SWIVEL BRACKET AND
BELLOWS”section (P7-7).
3
12
4
E
INSP
ADJ BELLOWS AND HOSE INSPECTION
UPPER UNIT HOUSING
3. After inserting the bearing outer race
with press, install the inner race. Use the
shimming tool, T5/T6a 1to measure the
clearance (Measurement B) between the
tool and the bearing with a thickness
gauge.
NOTE:
To have the clearance, measure the line be-
tween the point Aand Bon the bearing.
4. Find the stamped R-valve of the upper
gear case.
Shimming tool, T5/T6a:
6U4-28
A
B
1
B
E
UPPER
UNIT
16
8
7
2
3
4
5
⎧
⎪
⎪
⎪
⎨
⎪
⎪
⎪
⎩

SYMBOLS
Symbols 1to 0are designed as thumb-tabs
and indicate the content of a chapter.
1General information
2Specification
3Periodic inspection and adjustment
4Upper unit housing
56U41 Lower unit housing
66U51 Lower unit housing
7Intermediate assembly
8Steering system
9Power trim system
0Tr o ub le sh oo ti ng
Symbols Ato Hindicate specific informa-
tion:
ASpecial tool
BRecommended fuel
CLubricant
DEngine speed
ETightening torque
FSpecified value, measure, limit
GPress load
HResistance (Ω), voltage (V), electric cur-
rent (A)
Symbols Ito Kin an exploded diagram in-
dicate grade of lubricant and location of lu-
brication point:
IApply Yamaha gear-case lubricant
JApply water resistant grease
(Yamaha marine grease A)
KApply corrosion resistant grease
(Yamaha marine grease D)
Symbols Land Min an exploded diagram
indicate grade of sealing or locking agent,
and location of application point:
LApply LOCTITE®No. 271, 242, 572,1829
or 1501
MApply ThreeBond®TB-1322, 1324, 1524
or 1501
1
GEN
INFO
2
SPEC
3 4
UPPER
UNIT
5
INT
6
STEER
7
POWR
TRIM
8
90
AB
CD
EF
GH
I
T.R
INSP
ADJ
TRBL
SHTG
J
G
LT
TB
A
K
D
L
M
6U51
LOWER
6U41
LOWER

INDEX
GENERAL INFORMATION 1
GEN
INFO
SPECIFICATIONS 2
UPPER UNIT HOUSING 4
UPPER
UNIT
6U41 LOWER UNIT HOUSING 5
6U41
LOWER
6U51 LOWER UNIT HOUSING 6
6U51
LOWER
INTERMEDIATE ASSEMBLY 7
STEERING SYSTEM 8
POWER TRIM SYSTEM 9
POWR
TRIM
TROUBLESHOOTING
10
TRBL
SHTG
INT
STEER
3
INSP
ADJ
PERIODIC INSPECTION
AND ADJUSTMENT
SPEC

E
GEN
INFO
CHAPTER 1
GENERAL INFORMATION
OUTDRIVE IDENTIFICATION ................................................................................................. 1-1
Intermediate Assembly ..................................................................................................... 1-1
Drive Unit ........................................................................................................................... 1-1
Engine and Propeller Rotation .......................................................................................... 1-1
SAFETY PRECAUTIONS ......................................................................................................... 1-2
Prepare for Emergencies ................................................................................................... 1-2
Handle Fuel Safely ............................................................................................................. 1-2
Prevent Battery Explosion ................................................................................................. 1-2
Wear Protective Clothing .................................................................................................. 1-2
Keep Work Area Clean ....................................................................................................... 1-3
Operate Stern Drive Safely ............................................................................................... 1-3
PRE-DELIVERY INSPECTION ................................................................................................. 1-3
Check Engine Alignment ................................................................................................... 1-3
Inspect Drive Belts .............................................................................................................1-3
Check Gear Oil ................................................................................................................... 1-3
Inspect Outdrive Exterior .................................................................................................. 1-3
Check Power Trim System ................................................................................................ 1-3
Inspect Battery and Electrical Connections ..................................................................... 1-4
Check Remote Control Operation ..................................................................................... 1-4
Perform Test Run ............................................................................................................... 1-4
Drive Unit Break-in ............................................................................................................ 1-4
PROPELLERS ........................................................................................................................... 1-5
Propellers ........................................................................................................................... 1-5
Propeller Selection ............................................................................................................ 1-5
1

GEN
INFO E
OUTDRIVE IDENTIFICATION
Intermediate Assembly
The model and serial number plate 1is lo-
cated on the bottom surface of the interme-
diate housing.
OUTDRIVE IDENTIFICATION
1Intermediate Assembly
2Drive Unit
*Code Explanation:
DP–With Power Steering
DL–Without Power Steering, for Twin Installation
D–1.68:1 Gear Ratio
C–1.78:1 Gear Ratio
Engine and Propeller Rotation
Engine rotation is determined by looking at
the flywheel end of the engine. The Yamaha
engines covered in this manual rotate coun-
terclockwise to the left as viewed from the
flywheel.
As for the propeller rotation, the front pro-
peller rotates counterclockwise, and the rear
propeller rotates clockwise.
NOTE:
INT-HDP 6U0 DP *******
INT-HDL 6U0 DL *******
MODEL PREFIX VARIATION* SERIAL NO.
ABC D
INT-HDP 6U00 DP 1
INT-HDL 6U00 DL *******
DE-DHT 6U41 C 2
6U51 D *******
Drive Unit
The model and serial number plate 1is lo-
cated on the upper case of the drive unit.
The different models can be identified by
checking the model and serial number plate
and using the following plate.
1
1
YAMAHA MOTOR CO.,LTD.
MADE IN JAPAN
PAYS D'ORIGINE JAPON
A
B C D
1-1

GEN
INFO E
SAFETY PRECAUTIONS
Prepare for Emergencies
Be prepared for possible fires. Keep the fol-
lowing items handy:
¡First Aid Kit
¡Fire Extinguisher
¡Emergency Phone Numbers
SAFETY PRECAUTIONS
Wear Protective Clothing
Wear safety equipment whenever necessary:
¡Safety glasses or goggles
¡Earmuffs or earplugs
¡Safety shoes
¡Gloves
¡Respiratory protection
Avoid wearing loose clothing and jewelry.
Prevent Battery Explosion
Batteries produce explosive gases. Keep
sparks and flames away from batteries.
Check battery electrolyte level using a flash-
light.
Never check battery charge by connecting the
battery posts with a conductor. Use a volt-
meter or hydrometer. Always disconnect the
negative (–) cable first and reconnect it last.
DO NOT charge a battery if the battery is fro-
zen. Allow the battery to warm up first.
Charge the battery in a well-ventilated area.
Battery electrolyte is poisonous and danger-
ous. It contains sulfuric acid and causes se-
vere burns. Avoid contact with skin, eyes or
clothing. If electrolyte gets in the eyes, flush
with water for 15 minutes and get prompt
medical attention.
Handle Fuel Safely
Use care when handling fuel; it is highly flam-
mable. DO NOT smoke or have open flames
or sparks nearby when handling fuel.
Always clean up spilled fuel and dispose of
cleaning materials properly.
1-2

GEN
INFO E
Keep Work Area Clean
Properly ventilate your work area.
Keep the shop bench and floor clean and dry.
Cover all parts and part openings when they
are not being worked on, to prevent foreign
materials from entering and damaging the
drive unit.
Cleaning and protection of machined sur-
faces and friction areas are part of the repair
procedure; this is considered standard shop
practice.
Operate Stern Drive Safely
Remove the propeller. (Refer to “PROPELLER
SHAFT AND NUT INSPECTION” section (P3-
31).)
DO NOT operate engine without cooling
water supplied to the water inlet ports on the
drive unit.
SAFETY PRECAUTIONS / PRE-DELIVERY IN-
SPECTION
2
1
3
PRE-DELIVERY INSPECTION
Perform the following inspections to prepare
the outdrive for delivery to the customer.
Check Engine Alignment
¡Use an engine alignment tool to check
engine alignment. Make any adjust-
ments as necessary. (Refer to “ENGINE
ALIGNMENT” section (P3-29).)
¡Make sure all engine mounting hardware
is tight.
Inspect Drive Belts
Check the tension of the alternator belts.
Check Gear Oil
Make sure break-in oil is at the proper level.
Inspect Outdrive Exterior
¡Touch-up any painted surfaces with
matching paint.
¡Replace any parts damaged in shipping.
Check Power Trim System
¡Check the oil level of the trim pump res-
ervoir 1.
¡Make sure all wires 2and hydraulic lines
3are connected properly.
¡Use the trim switch to check the trim op-
eration. Make sure lines and
wireharnesses do not bind and are not
interfered with when the outdrive is
moved up, down, right or left.
1-3

GEN
INFO E
Inspect Battery and Electrical Connec-
tions
¡Check the battery fluid level.
¡The battery should be fully charged.
¡Make sure the battery is mounted se-
curely in the boat.
¡Battery cables must be connected cor-
rectly and must be tight.
¡Inspect all wireharness connections for
proper contact and tightness.
Check Remote Control Operation
¡Make sure the drive unit can be con-
trolled properly from the remote control.
PRE-DELIVERY INSPECTION
Perform Test Run
¡Make sure gear shifting and steering is
smooth.
¡Check for any leaks in the transom.
Drive Unit Break-in
NOTE:
Allow a 10 hour break-in period for the drive
unit. If the drive unit is new or if the drive
gears have been replaced, observe the fol-
lowing steps to allow the gears a break-in
period.
1. Avoid full throttle starts. Ease the boat
into motion.
2. DO NOT operate the unit at any one
steady speed for more than 5 minutes.
3. DO NOT operate the engine at more than
3/4 of full throttle for the first 5 hours of
operation.
4. Operate the engine at full throttle only
intermittently during the next 5 hours.
5. The drive unit should be shifted into front
drive gear a minimum of 10 times dur-
ing the break-in period, with run-in time
at moderate r/min. after each shift.
1-4

GEN
INFO E
PROPELLERS
PROPELLERS
Propellers
As the propeller turns, water is pushed down
and back, creating a positive pressure on the
face of the blade. At the same time, a nega-
tive pressure is produced on the back of the
blade, thus sucking water to it. The positive
and negative pressures cause the boat to
move forward.
The propeller size indicates the propeller di-
ameter, pitch and type or style.
The pitch of a propeller is the distance the
propeller will move forward in one complete
revolution. (This is similar to the pitch of a
screw as it moves into a hole.)
The pitch indicated by the propeller size is a
theoretical or designed pitch. The actual for-
ward motion on each revolution is less than
the theoretical pitch. The difference is known
as the “slip” of the propeller.
Water is a fluid which gives way a little un-
der the pressure of the blades. A 10 % to 15 %
slip is considered acceptable.
Propeller Selection
Because of the many designs and different
materials used, it is necessary to select the
right propeller for the boat’s specific use. A
boat can be used for various uses such as
skiing, cruising, fishing, racing, towing, etc.
Different designs affect the boat and engine
differently. Depending on the propeller de-
sign, the speed, acceleration, engine life, fuel
economy, and boating and steering qualities
can be changed to fit the particular needs of
the boat by changing propellers.
The material the propeller is made of and
where the boat is used, for example; in riv-
ers, seas, shallows, rock-bound waters, high
mineral waters, etc. are also important. Alu-
minium propellers are economical, have
good strength, good corrosion resistance and
are easily repaired. Stainless steel propellers
have tremendous strength and superb cor-
rosion resistance.
Whatever the purpose of the boat, always
make it a habit to carry spare propellers and
hand tools. In case of heavy propeller dam-
age, you will be able to rely on the spare pro-
peller to power you to a nearby port.
Below is a list of Yamaha propellers avail-
able through your dealer.
Position
No. of Blades Diameter (in.) Pitch (in.) Material Part Number
F3 1519
Stainless Steel
F↑↑20 ↑
F↑↑21 ↑
F↑↑22 ↑6U4-45942-00-98
F↑↑23 ↑6U4-45946-00-98
F↑↑24 ↑6U4-45951-00-98
F↑↑26 ↑6U4-45955-00-98
F↑↑28 ↑6U4-45959-00-98
R↑↑19 ↑
R↑↑20 ↑
R↑↑21 ↑
R↑↑22 ↑6U4-45944-00-98
R↑↑23 ↑6U4-45948-00-98
R↑↑24 ↑6U4-45953-00-98
R↑↑26 ↑6U4-45957-00-98
R↑↑28 ↑6U4-45961-00-98
F: Front, Counterclockwise Rotation
R: Rear, Clockwise Rotation
1-5

E
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS .................................................................................................. 2-1
Outdrive Specifications ..................................................................................................... 2-1
Drive Unit Dimensions ...................................................................................................... 2-2
MAINTENANCE SPECIFICATIONS ........................................................................................ 2-3
Hydraulic Clutch System ................................................................................................... 2-3
Power Trim System ........................................................................................................... 2-3
Tightening Torque .............................................................................................................. 2-4
Calculation to Obtain the Correct Torque Wrench Reading (Setting Value) ................. 2-6
Tightening Torque Specifications for Standard Bolts and Nuts..................................... 2-8
Pre-coated Bolts (With Seal-locking Agent Applied on the Threads) ............................ 2-9
SPECIAL TOOLS ...................................................................................................................2-10
STEERING CABLE REQUIREMENTS ................................................................................... 2-15
STANDARD ABBREVIATIONS AND SYMBOLS ................................................................. 2-16
Measurement ................................................................................................................... 2-16
Color Codes ...................................................................................................................... 2-16
WIRING DIAGRAM ............................................................................................................... 2-17
Power Trim/Tilt System Wiring Diagram ....................................................................... 2-17
DRAWINGS AND DIMENSIONS .......................................................................................... 2-18
Cross Section Drawing .................................................................................................... 2-18
Exploded Drawing ........................................................................................................... 2-19
SPEC
2

SPEC E
GENERAL SPECIFICATIONS
Outdrive Specifications
GENERAL SPECIFICATIONS
Model name
Items
Upper (Driven/Drive)
Gear ratio Lower (Driven/Drive)
Tot a l
Clutch system
Drive unit oil capacity
Drive unit recommended oil
Mounting form
Steering system
Steering angle
Tilt/trim system
Tilt angle
Tri m a ng le
Power trim/pump recommended oil
Power trim/tilt system oil capacity
Propeller driving system
Exhaust system
Cooling system
Lubricating system
Tra n so m len gt h
(crankshaft center – cavitation plate)
Weight
(dry, without power steering cylinder)
Power steering
INT INT-HD (6U00)
Drive
DE-DHT-C (6U41) DE-DHT-D (6U51)
35/30 35/30
26/17 26/18
1.78 1.68
Hydraulic clutch system
2.4 L 2.45 L
Yamaha Stern Drive Gear Oil or Hypoid Gear
Oil (SAE90) GL-4, GL-5 or equivalent
Direct mounting on transom, gimbal ring type
Steering guide system
30°each, right and left
Hydraulic tilt/trim system
46.5 °(in reference to 13 °transom)
– 6 °to 15 °(in reference to 13 °transom)
Automatic Transmission Fluid (ATF)
Dexron Type II.
0.82 L
Spline drive system
Through propeller hub
Inlet on the lower case side, seawater pump
located at the front of the engine
Integrated (upper and lower) oil chamber and
oil pump
351.5 mm
107 kg
Standard
2-1

SPEC E
Drive Unit Dimensions
* Dimensions are based on a boat transom angle of 13 °. Dimensions will change slightly
when used on boats with transom angles other then 13 °.
474
351.5 250.5
267.9
290.2
575
809
822
980.8
417417
13
GENERAL SPECIFICATIONS
2-2