Can’t See the
Converter for
the Trees
by Mike Souza
www.atra.com
T
oo often technicians blame some- converter O-ring. 8.3L engines have an internal thermo-
thing they can’t see, only to find This next bit of information may stat in the cooler line near the radiator
that the answer was right there in affect all Chrysler and Dodge vehicles: (thermostatic bypass valve; figure 6). If
front of them the whole time. A failed A restricted cooler may cause the engine the thermostat sticks, it may cause the
torque converter is a good example: You to stumble or stall (same symptom as a same complaint as a restricted cooler.
can’t see inside the converter, and may weak or broken TCC limit spring), You can check this by running a hose
not see the original reason why it failed, especially when cold (figure 5). between the cooler line fittings, bypass-
even though the root cause might be in Vehicles equipped with 5.9L or ing the entire cooling system. Over
plain sight. Like not seeing the forest
(cause of failure) for the trees.
The examples we’ll look at involve
Chrysler and Dodge vehicles. The sub-
ject is torque converter problems before
and after rebuild, or repeated converter
failure after delivery. So it’d be easy to
blame the converter when that may not
be the actual cause of the failure.
45/545RFE and 68RFE units have
pump assemblies that look very similar.
The critical difference between these
units is the spring tension for the TCC
limit and pressure regulator valves. The
45/545RFE springs are lighter (figure
1); if you install any of these compo-
nents in a 68RFE transmission, it’ll
cause lower line pressure and TCC slip
Figure 1
codes.
Excessive valve bore wear can
cause torque converter chatter, slip
codes, and premature failure.
The clip at the end of the TCC
accumulator valve bore often breaks;
this will affect converter clutch apply
feel.
The TCC accumulator spring may
become weak or broken, causing harsh
TCC apply (figure 2).
A weak or broken TCC limit valve
spring will cause the engine to stumble
or stall (figure 3).
A missing or damaged converter
O-ring could allow converter drain-
back, causing delayed engagement
when cold (figure 4). It could also
cause a crossleak and set TCC codes.
So far we haven’t seen any calls to the
ATRA HotLine caused by a missing Figure 2
4 GEARS March 2010
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