TSB-19-14-001

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SUBJECT:
WATER PUMP COOLANT LEAKAGE:
INSPECTION PROCEDURE
No:
TSB-19-14-001
DATE:
January 2019
MODEL:
All models
CIRCULATE TO:
[ ] GENERAL MANAGER
[ X ] PARTS MANAGER
[ X ] TECHNICIAN
[ X ] SERVICE ADVISOR
[ X ] SERVICE MANAGER
[ X ] WARRANTY PROCESSOR
[ ] SALES MANAGER
PURPOSE
This TSB contains supplemental information with a coolant leakage inspection procedure to
prevent unnecessary replacement of the water pump.
BACKGROUND
Replacement of water pumps has been carried out during periodic vehicle maintenance because
some coolant leakage is found in the vicinity of the steam vent hole or the water drain hole.
However, this replacement is usually unnecessary because it is normal that steam or mist passes
through the mechanical seal, which is used to seal the rotating shaft portion of the water pump.
The steam or mist that passes through the mechanical seal escapes from the steam vent hole or
the water drain hole and does not affect the seal performance.
AFFECTED VEHICLES
All models and model years.
INSPECTION PROCEDURE
Refer to the Inspection Procedure that follows when coolant leakage is discovered near the steam
vent hole or the water drain hole to determine if replacement of the water pump is necessary or
not.
Copyright 2019, Mitsubishi Motors North America, Inc.
Continued
The information contained in this bulletin is subject to change. For the latest version of this document, go to the
Mitsubishi Dealer Link, MEDIC, or the Mitsubishi Service Information website (www.mitsubishitechinfo.com).
(4791)
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TSB-19-14-001
Inspection Flow When Coolant Leak Is Found During Periodic Maintenance
* Checking Method
1. If water drain hole is visible:
Confirm there is a leakage mark under the drain hole.
2. If water drain hole is not visible:
Confirm there is a leakage mark on underside of water pump.
(whether water pump is visible or not)
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TSB-19-14-001
Mechanical Seal
The water pump rotating shaft portion is sealed with a mechanical seal. Due to its structure, steam
or mist escapes to the outside under normal conditions, and is sometimes misjudged to be coolant
leakage.
Mechanical Seal
Water Pump
Cross Section
Steam Vent
Hole
Water
Drain Hole
Carbon
Ceramic
Sliding Portion
Coolant
Side
Outside
Lubrication
& sealing
for sliding
portion
Sliding
Face
It is normal for steam or mist
to come out here
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TSB-19-14-001
Water Catcher
On some engines, a water catcher is provided to prevent water leakage from the drain hole (as
shown below). In this case, it could be considered abnormal if a wet water leakage mark is identified
around the drain hole. Refer to “Inspection Flow When Coolant Leak Is Found During Periodic
Maintenance” earlier in this TSB.
Water Catcher
(3B2 engine shown as example)
Water Pump
Cross Section
Water
Drain Hole
Normal Condition
The photos below show an example of a normal condition of coolant leakage residue.
Example of Normal Condition
Water Pump Drain Hole
Water Pump Drain Hole
WARRANTY INFORMATION
This bulletin is supplied as technical information only and is not an authorization to repair. If an
affected vehicle is reported with the described condition, diagnose the condition, repair as
described in this bulletin and submit a normal warranty claim.