MACS Monthly Newsletter - 2019 - JAN1

Total Vehicle Climate and Thermal ManagementTM

January 2019

By Paul Weissler, MACS Senior Technical Correspondent

IS THE WATER PUMP BAD?
practical today, although sight glasses with and
without built-in air bleeds are sold on the internet
(Figure 1).

Stealth Conversions

Diagnosing poor performance from engine-driven water pumps is certainly one of the toughest
troubleshooting jobs in cooling system service. At
this time of year, poor heat is one of the more likely
jobs a shop will see, and a weak water pump is just
one of the many causes of poor heat, of course. But
diagnosis often comes down to checking for poor
flow through the cooling circuit. If the car has an
auxiliary electric water pump, troubleshooting a
failed pump and its control circuit is fairly straightforward, but isolating a problem to an engine belt
driven, all mechanical pump is another matter. And
no shop wants to invest the labor in removing some
of today's water pumps without a strong indication
that the pump operation is the issue.
Judicious use of an infrared thermometer can pinpoint blockages in the cooling system, but determining a pump is capable of (and delivering) good
flow is another matter. Years ago, in-line flowmeters were readily available for checking flow (still
see some of them sold on eBay), and some shops alternatively spliced clear sight tubes into the upper
radiator hose connections. Neither is particularly

Figure 1: Cutting an upper radiator hose to insert a sight
glass is a somewhat extreme procedure, hence seldom performed today. But if you really want to use that approach
to check for good coolant flow, sight glasses still are sold on
the internet.

ALSO INSIDE THIS ISSUE:
SOMETIMES WE THINK TOO HARD .............................................................................................................................. 4
WHEN THE "QUICK CHECK" IS MISLEADING .............................................................................................................. 5
LEAK DETECTION: JUST KEEP IN MIND ...................................................................................................................... 6
THINK BEFORE YOU START ........................................................................................................................................... 7
NO HEAT MOST OF THE TIME.......................................................................................................................................... 7
ANOTHER WARNING ABOUT CONSTRUCTION VEHICLES: POOR AIRFLOW ........................................................... 8

MACS Service Reports is the official technical publication of the Mobile Air Conditioning Society Worldwide, Inc., P.O. Box 88, Lansdale, PA 19446. The material published in MACS Service Reports expresses the views of the contributors
and not necessarily that of MACS. Every attempt has been made to ensure

January 2019

the accuracy of the content of MACS Service Reports. MACS, however, will
not be responsible for the accuracy of the information published nor will MACS
Worldwide be liable in any way for injury, labor, parts or other expenses resulting
from the use of information appearing in MACS Service Reports.

MACS Service Reports

MACS Monthly Newsletter - 2019

Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2019