MACS Monthly Newsletter - 2017 - MAR8

Ford Motor Company

AAT would be slim to none. If, however, the DTC
in another module were related to stability controls or traction controls, it would be very much
within reason to suspect a relationship between the
two DTCs. In order to perform proper torque management (engine power reduction) in the operation
of both traction control systems and stability control systems, an engine management system needs
to be in tip top working order. Even a sensor like
OAT / AAT traditionally tied exclusively to HVAC
/ Displays can now upset the engine management
system's 'apple cart' which can result in another
system's DTC - the stability / traction control system. ■

Figure 11: This Ford MySync radio display shows ambient temperature
and requested HVAC set point temperatures on its display. This information has been sent via a data bus from other modules. The display will not
update with inaccurate outside air temperatures in the event the vehicle
has stopped and is undergoing heat soak from the radiator / condenser on
to the sensor.

Water Pump Weeps
Most modern engines use some type of water pump to circulate antifreeze through the engine and heat exchangers
to regulate operating temperature. Many of the engine driven pumps contain shaft seals that are lubricated by the
coolant itself. As part of the pump's normal operation, these seals are in direct contact with the coolant, which leaks
(extremely) slowly past the seal as it provides lubrication. Once past the seal this small amount of fluid collects in an
area known as the weep chamber. It's a place where this leaked coolant has a chance to evaporate, its vapor escaping
through a vent or weep hole.
Older style water pumps had a similar setup, although they were designed to simply allow the lubricating coolant
to drip past the water pump seal and into the weep hole and drip down out of the pump housing, along the front of
the engine and eventually down onto the ground, that is if it could make it that far. In most cases, especially when the
vehicle is in motion or the engine cooling fan is operating, that dripping coolant would be blown across the front of
the engine and evaporate relatively quickly so as to not cause alarm, although over time a rusty stain may develop.
As the water pump shaft seal wears out further, the coolant leak rate can increase to the point where it becomes a
visible drip or puddle requiring replacement of the pump.
To help technicians diagnose their newest style of water pumps, Ford has issued GSB (General Service Bulletin) #
GSB-0000083, "Cooling System - Coolant Pump Warranty Information," intended to explain coolant pump design
characteristics and features, what normal staining looks like and to show an example of a leak, along with a diagnostic tip. It's all in an effort to explain what water pump weeping is and how to figure out if now is the time to replace
the pump or not.
Newer model Ford engines, such as the 2.0-Litre 4 cylinder in the 2012 Focus use a type of water pump with a
coolant-lubricating seal and integral weep chamber. Any coolant that collects in the chamber later evaporates with
normal usage. Sometimes this can result in an exterior stain due to the vapor escaping past the vent hole and collecting on the pump housing rather than on the inside of the weep chamber. Ford wants technicians to know that this is
a normal characteristic of this pump style and is not an indication of failure. But if there is wet coolant or puddles on
the weep chamber, a quick test can determine whether or not the pump needs to be replaced.
Dry the coolant pump housing using a clean paper towel. You might have to wipe the area a few times, especially
if there's dirt, oil or grime. Allow some time then wipe it again. If the towel only has a dry or waxy residue, the seal
is working properly. But if the towel is wet, the pump is leaking and needs to be replaced.

MACS Service Reports is published monthly by the Mobile Air Conditioning Society
Worldwide. It is distributed to members of MACS Worldwide and is intended for
the educational use of members of the automotive air conditioning service and
repair industry. Suggestions for articles will be considered for publication, however,
MACS Worldwide reserves the right to choose and edit all submissions.

Editors:
Elvis Hoffpauir, Steve Schaeber
Production Designer:
Laina Forcey
Manager of Service Training:
Steve Schaeber
Mobile Air Conditioning Society Worldwide
P.O. Box 88, Lansdale, PA 19446
Phone: (215) 631-7020 * Fax: (215) 631-7017
Email: membership@macsw.org * Website: www.macsw.org

Unless otherwise noted, all photos/art by author.

March 2017

MACS Service Reports

http://www.macsw.org

Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2017