RUNNING ON AND
KEEPING COOL
FIRST LINE discusses the growing popularity of auxiliary
electric water pumps and how to remedy replacement issues.
Modern, low-emission, high-output engines have to run within a very
small temperature range in order to maintain their efficiency. The water
pump allows this to happen by regulating the coolant flow according
to the demand of the ECU. Furthermore, forced induction engines will
require additional cooling of the turbo/supercharger after shutdown in
order to prevent premature wear or even damage.
When the engine is switched off, the electric pump is designed to
continue pumping coolant for a number of minutes. This occurs until
the turbo has sufficiently cooled which manages the temperature,
prolonging the turbo’s lifespan.
AVOID GETTING TOO HOT
When a turbocharged vehicle is switched off,
the temperature of a turbo bearing can
reach up to 340°C within seconds.
This temperature can cause the
oil in the bearing housing
to lose viscosity
and lubricating
properties. This
causes the bearing to
wear and leads to the
failure of any rubber
or plastic seals.
WHAT CAN GO WRONG?
IMPORTAN
In order to ensure the longevity of a repair job, it is important understand the true causes.
BMW 3, 5 Series, X3, X5 & Z4 with N51,
N52 and N52K engine
These vehicles have a tendency to
experience water pump failure at around
60k-100k miles.
The issue isn’t typically a leak or mechanical
breakdown. However, it often starts out as a
problem with the electric motor in the pump
that begins to slow down, eventually coming
to a complete stop. Monitored by the primary
vehicle control module, it’s only detected
during a system scan which will read as
a water pump speed deviation or loss of
communication to the water pump.
If undetected by a system scan, the only
warning will be the yellow light illuminating,
followed shortly by a red light indicating
engine overheat.
DO NOT DRIVE THE VEHICLE IN THIS
CONDITION. This can lead to a costly engine
replacement/overhaul as a result of heat
damage.
Volkswagen T4
Fitted with a primary electric water pump in
addition to a traditional belt driven option,
a number of drivers have complained that
the water pump continues to run long after
the set period when the vehicle has been
switched off, running the battery flat.
In this case, the
water temperature
sensor has simply
failed and locked
open, causing the pump
to continuously run.
It is imperative T!
old coolant is th that
orou
flushed throug ghly
h an
fresh coolant m d
ix is
used with any
water
pump repairs.
Range Rover/Range Rover Sport Mk3
(2005-2009)
The wires that go into the electric water
pump connector (C3006) may have been
wired the wrong way. As a result, the
auxiliary coolant pump that cools the
supercharger runs backwards. Over time,
this degrades the pump and causes it to fail
or run very poorly.
FIRST LINE SUPPORT
First Line offers comprehensive technical information to support their
extensive catalogue. Visit www.firstline.co.uk/technical-support
for more technical bulletins and information.
VITAL NEWS ISSUE 49
All First Line products come with a 24-month/24,000-mile warranty
from the time the product is fitted. Available from FPS via same/next-
day delivery, please speak to your local FPS representative for more
information.
ELECTRIC WATER PUMPS 9