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26 AUTOMOTIVE AFTERMARKET MAGAZINE NOVEMBER 2013
Avoiding ‘sponge state’ in hydraulic tensioners
Protect your warranty with correct installation practise.
Although this information is most relevant
for Mitsubishi applications, it also generally
relates to all hydraulic tensioner installations.
The checks outlined in this article can, and
should, be carried out on all hydraulic
information is suitable
for the Mitsubishi
Starwagon, Triton and
Verada models with a
3-litre or 3.5-litre V6
engine made from
1994 to 2008.
part numbers include
and TCKH287 and it
should be noted that
the Gates hydraulic
tensioner GHT-01 is
an OEM exact
It is critical that
the hydraulic tension
is checked before
There is a small chamber in the hydraulic
actuator/tensioner that air can leak into which
can lead to a ‘non-damping’ situation.
The manufacturers of the hydraulic
actuators refer to this as ‘sponge state’.
If the tensioner/ actuator is affected by the
sponge state then a bleed out procedure is
Failure to do so can lead to the timing belt
jumping teeth, causing expensive engine
The retaining pin should only be removed
after the installation of all components.
The reason for this guideline is that once
installed, the hydraulic tensioner is in a vertical
position and there is no risk of air expel.
Also, if the pin is released with no
resistance and travels to its fully extended
position air will expel and
the sponge state will have
Other components within
the timing drive can affect
the performance of the
actuator/tensioner so it is
critical that the vehicle
procedures are followed
It is also recommended
that hydraulic actuators/
tensioners should be stored
in a vertical position with the
visible part of the piston rod
pointing to the top to avoid
The pin retaining the
piston rod should not be
removed until it is installed
as recommended by the
If there is any movement in the piston rod
after correctly following the installation
procedures, remove the hydraulic tensioner
leaving the piston rod in the extended position
for further inspection.
The piston should be solid and require
considerable force to move. This can be
checked by pressing the piston against a firm
If there is any movement, the unit will
require a bleed out procedure.
If the bleed out procedure is not followed,
premature failure will most likely occur.
Bleed out procedure
WARNING: If a horizontal press such as a vice is
used, the air entrainment may occur, so a vertical
press must be used.
If the compression is too fast, the procedure
may damage the rod. Make sure to compress
slowly and thoroughly.
To prevent damage to the auto tensioner, do
not push down the rod exceeding the bottom end
(a position where the rod protrusion is at 0.5mm
from the auto tensioner).
1. Set the actuator/tensioner with the piston rod
in the extended position to a vertical press
and then slowly compress the piston rod to
the bottom end, then slowly extend. Repeat
this step two to three times (each cycle should
take no less than a minute to avoid damage).
2. Compress the rod slowly and then align the
set hole of the rod with the set hole of the auto
tensioner body and insert the retaining pin.
3. Install the auto tensioner in position. Leave
the wire or pin installed.
4. Follow the vehicle manufacturer’s specific
installation procedures to ensure problem free
5. If there is still movement in the piston rod,
repeat this procedure.
NOTE: If after repeating this procedure several
times and the piston rod does not return to a solid
state, replace the tensioner.
As the sponge state is avoidable by following
the vehicles manufacturer’s installation
instructions and/or being
aware of the above checks
warranty claims will be
honoured by Gates when
sponge state has occurred.
Scan the QR code with your smartphone or visit
www.GatesAustralia.com.au/feedback to tell Gates
about a problem you have come across, or any
technical information you are looking for.
AAAM NOV 2013:AM MAGAZINE SHELL 15/11/13 11:58 AM Page 26
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