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Transmission Fluid
Evacuation Service
There has been a recent trend toward use of
fluid evacuation systems in the automatic transmission service industry in lieu
of traditional transmission service methods. These systems are used to pump the
old fluid out of the transmission and to refill with fresh fluid. This avoids
dropping the pan and draining the unit which can be time consuming and messy.
The use of this method to replace the transmission fluid is a clean, efficient,
and safe way to remove hot oil from a transmission. The problem, however, is
that often times it is mistakenly thought that this represents complete
transmission service and that removal, and cleaning of the pan and inspection and
servicing of the filter are unnecessary.
Some people believe that all transmission
filters are back flushed clean every time the vehicle is turned off. This is a
major misconception. Three-quarters of all transmission filters today are not a
simple screen, they are made of felt. A felt filter CANNOT be back flushed. Felt
holds dirt particles within tiny pores in the felt. It will not wash out or
flush out. If a felt filter becomes clogged it must be replaced. Clogged filters
restrict fluid flow, which lowers pressure to clutches and bands. This can cause
slippage and eventual burnout of the transmission.
Service manuals and textbooks on transmission
service recommend that a transmission filter be inspected and replaced, if
necessary, as often as every 15,000 miles (24,140km), for severe service such as
city driving, desert (hot dusty) driving, extreme cold, frequent short trips,
trailer towing, and delivery service. In normal operating conditions the manuals
recommend to inspect and replace the filter at least every 30,000 miles
(48,280km). Even the newer vehicles with 100,000 mile (160,934km) drive train
service warranties, the manufacturer recommends filter replacement if the
vehicle sees severe service conditions.
There have been an increasing number of
instances surfacing recently regarding transmission failures shortly after an
evacuation service, without filter removal. At the time of a fluid evacuation
service, there is no way to know the condition of the filter and how clogged it
may be. The filters job is to collect and hold contaminants, (dirt, metal
filings, friction particles, etc.), and prevent these particles from causing
malfunction in such components as electronic force motors and solenoids. Today's
transmissions are far more susceptible to malfunctions caused by fine dirt
contamination. Without servicing the filter, there is no way to know if the
filter is clean of debris or nearing capacity. If the filter is nearing
capacity, transmission failure may not be far off. This is also a sign that
there may be other internal problems in the transmission. Recognizing these
warning signs could eliminate major service later.
Most of the transmission failures after an evacuation service have occurred
primarily on relatively high mileage transmissions that have not been serviced
in some time. One reason for this is that the sludge and dirt buildup within the
transmission will not completely be removed during the service. When the new
fluid (which has detergent properties) is placed in the transmission, over days
and weeks, the internal components begin to wash the insides of the
transmission.
This sludge does finally work loose and
settles in the transmission filter, clogging it up even further than it may have
been before service. In these extreme cases, where service has not been
performed in some time, changing the filter may not completely fix the problem.
Some mechanics recommend a second service a few weeks after
the first, replacing the filter again, which may be partially clogged due to the
cleaning process in the transmission.
Even if the fluid evacuation method is desired
to remove the used transmission fluid, the pan should be removed also, and an
inspection should be made of the pan contents, fluid, and filter to determine
the condition of the transmission. Aluminum filings in the pan or iron filings
on the pan magnet are signs of internal wear and may give light to potential
problems in the transmission. Transmission service is performed for preventative
maintenance. Evaluating the overall condition of the transmission by removing
the pan should be part of this preventative maintenance also.
The Filter Manufacturers Council urges
everyone to dispose of all used filters properly.
T's Advanced Synthetics
Greg and Marcy Thurman
Your Nationwide
AMSOIL
Authorized Independent
Dealer
Nationwide US Warehouses,
Canada and Palm Harbor, FL
727-798-8552
E-Mail:
greg@tsadvancedsynthetics.com
If you
experience problems or have questions or comments about
our website please email us at
greg@tsadvancedsynthetics.com
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