This bulletin applies to Chyrsler models equipped with a 6.1
L engine with an engine serial number of TNXE6026620001 or less. The
engine serial number can be found on a label located on the upper side
of the left or right engine front cover.
SYMPTOM/CONDITION:
Some customers may notice a whine sound at idle after the vehicle has
been driven (engine hot) in warm ambient temperatures over 50° F (10°
C). This sound can be caused by the piston oil cooler jets fluttering
during hot oil/idle conditions.
DIAGNOSIS:
Installers must carefully diganose this whine sound since it can be
confused with other sounds that come from the engine compartment.
1. Run the engine until the oil is hot, over 230°
F (110° C). Use the digital display located in the instrument cluster
for oil temperature.
2. Allow the engine to stabilize at idle and read the oil pressure using the digital display located in the instrument cluster.
3. Shut the engine off and wait 10 seconds.
4. Restart the engine with NO throttle application, allow the engine to settle at idle RPM.
5. Note the oil pressure as it may read 1 to 2 PSI
less than step 2. If this is the case, the whine sound may be heard. If
the procedure is followed closely, the whine sound can be turned on and
off with a slight change to oil pressure. The piston cooling jets are
operating properly but high oil temperature results in slightly lower
operating oil pressure at idle and can cause the valve inside the oil
cooler jets to flutter.
If a customer complains about this sound, it should be noted that no
detrimental effect or engine durability is caused by the jets
fluttering. If the customer wants this noise eliminated, it is
recommended by Chrysler to use 15W50 Mobil One engine oil in warmer
(summer) months and revert back to 0W40 Mobile One engine oil in cooler
months. If the oil viscosity is changed, a label indicating this should
be installed.
Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.
