Dual Mass Flywheel Diagnosis
Check for Thermal Overload
Note: These quick
information shall help to carry out a correct diagnosis in case of
a customer complaint.
Through friction of clutch plate on the friction surface of the
dual mass flywheel temperatures up to 200 °C can arise during
normal driving. At sliding clutch or through operating errors much
higher temperatures can arise. These temperatures must not cause
mandatory a reduced lifetime of the dual mass flywheel.
Possible indications for a high thermal load are:
• |
Tarnish (bluish) as well as
local hotspots on friction surface |
• |
Tarnish (bluish) near of
mounting area and riveting area of clutch |
If all other checkable features are well, the dual mass flywheel
can stay in the vehicle.
Possible indications for a too high thermal load are:
• |
Fusion zones on friction
surface (material smear) |
• |
Scores in friction surface
(for example through clutch lining riveting at destroyed or worn
clutch plate) |
• |
Tarnish (bluish) which reaches
up to bearing area of dual mass flywheel |
• |
Bluish discoloration of
locating pins (3 locating pins in outer zone of dual mass
flywheel) |
In these cases the dual mass flywheel has to be replaced.
Overview Dual Mass Flywheel
(1) |
Bearing Area |
(2) |
Mounting Area Pressure Plate |
(3) |
Locating Pins |
(4) |
Friction Surface |
(5) |
Riveting Area |
Exploded View Dual Mass Flywheel with Additional Mass
(1) |
Secondary Flywheel Mass |
(2) |
Additional Mass, Coupled with Cover and
Pulse-Generator Ring |
(3) |
Flange |
(4) |
Primary Flywheel Mass with Bowed Springs and Plain
Bearing/Bearing Bolt |
(5) |
Toothed Ring |
Check for Damaged Components
All following checking procedures have to be carried out at
installed dual mass flywheel. For visual check at vehicle very
bright light and a additional bright and small pocket lamp is
necessary. Damages like grease on primary flywheel and loose ore
missing balance weights cannot be checked at installed condition.
During visual check material alteration can be stated which
eliminate a further operating suitability.
For comparison different damages at dual mass flywheel with the
corresponding further procedure are presented here.
|
Note: In case of
mechanical damages at plain bearing the dual mass flywheel has to
be replaced.
|
1. |
Inspect plain bearing (1) for
damages. |
|
Dependent of the manufacturer damages can be detected through
ventilation openings of secondary flywheel. Parts of the bearing
(1) are detached or lie loose around the bearing bolt. |
|
Note: Light abrasion
on frontal areas of teeth is allowed. If problems occur during
starting the engine the dual mass flywheel has to be replaced.
|
2. |
Inspect toothed ring (1) for
damages. |
|
The toothed ring is needed to start the engine. Through a lot
of starting procedures and/or an incorrect engaging starter signs
of abrasion can occur on teeth of the toothed ring. The profile of
damages can reach from only low signs of abrasion up to heavy
material removal. The installation of a pulse-generator ring
depends on the manufacturer. |
|
The image shows signs of abrasion and mechanical damages at
toothed ring (1), they occur through abrasion due to a lot of
starting procedures. In this case the dual mass flywheel has to be
replaced. |
|
Note: The check must
be carried out only by hand without any tools.
|
3. |
Inspect tilt clearance.
|
|
At dual mass flywheel the additional-mass ring looms over the
gap between primary and secondary flywheel. It is not possible to
carry out just a visual check. |
|
Note: An absolute
clear measurement is not possible with this check due to the
different applied forces of the several workshop employees during
the check.
|
4. |
Embrace dual mass flywheel and
apply thumbs onto the outer radius of secondary flywheel.
|
5. |
Apply pressure onto the
secondary flywheel alternating on upper, lower, left and right
side |
|
During the tilt clearance check a functional metal rattling
noise may occur. |
|
If tilt clearance is higher than 3 mm (MUST be measured,
DO NOT make an estimation) (1) the dual mass flywheel has to be
replaced. |
6. |
Inspect clearance angle
(1). |
|
Before the inspection of the clearance angle the dual mass
flywheel should be rotated several times clockwise and
anticlockwise to receive a feeling for the resistance of the
springs. In addition unusual loud clicking noise or possible
rattle, crunch, grinding noise can be sounded out during rotating
the dual mass flywheel. |
|
If the rotation of the flywheel is impossible the flywheel is
defective and has to be replaced. |
|
The clearance angle is the angle (1) about the secondary and
the primary flywheel can be turned light against each other.
Thereby the flange wings are moved in the duct of the bowed springs
without adjoining the bowed springs. Dictated by functional factors
the clearance angle is up to 8 teeth. |
|
Is the secondary flywheel rotated beyond this point the bowed
springs in the duct are moved to spring arrestor in the primary
flywheel/cover. First now the spring force of the bowed springs is
active. |
|
• |
Rotate secondary flywheel
anticlockwise (arrow) until the elastic counterforce (spring force)
is clear noticeable. |
|
• |
Release secondary flywheel
slowly until the bowed springs are relaxed, so no counterforce acts
onto the springs. |
|
• |
Mark position with a vertical
line by a white pencil on secondary flywheel (1) and on toothed
ring for starter (2). |
|
• |
Rotate secondary flywheel
clockwise until the elastic counterforce is clear
noticeable. |
|
• |
Release secondary flywheel
slowly until the bowed springs are relaxed. |
|
• |
Apply new marking on secondary
flywheel (1) on the height of the marking on the toothed ring for
starter (3). |
|
• |
Count amount of teeth on
toothed ring for starter from marked tooth up to the height of the
first marking on secondary flywheel (2). Dictated by functional
factors up to 8 teeth are allowed. |
7. |
ALWAYS replace the engine
flywheel if following conditions are given: |
|
• |
The difference exceeds the
amount of 8 teeth. |
|
• |
The dual mass flywheel cannot
be rotated. |
|
• |
During rotating the dual mass
flywheel a hard metallic arrestor is audible or noticeable.
|
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