| checking trans fluid per the manual [message #193895] |
Mon, 24 December 2012 13:38 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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There has been a lot of discussion about the temp of the tranny oil having a bearing on the level. Flame me if you want but here are the facts in my experience. I have a 79 KW with an Allison 754 CRD automatic tranny. It holds 43 qts of Dextron (and 15-40 motor oil is an option for sevier duty as in the garbage trucks that run locally. I had a 69 Chevy 327 with 350 turbo that PO had motor oil in and it worked great. The difference is Dextron is for use above -13*F and 15-40 for use above +5*F.) Back to the Dextron, if I overfill the KW 1 qt it will run hot and the fluid expands more since it is hotter than normal and will puke a gallon out the overflow on the exhaust and smoke like crazy. I have to stop and let it idle to operating temp and refill to correct level. This is explained here.
http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=MT1366EN.pdf
The GMC manual states the same.
http://www.bdub.net/manuals/X7425/X7425.pdf
7-44 Oil Level
The transmission dipstick and filler tube is
located under the engine access cover at the left center
side of the engine . The "FULL" and "ADD"
dimple marks on the transmission dipstick indicate
one pint difference. Correct fluid level is determined
at normal engine coolant operating temperature
(180°F-190°F) . Careful attention to transmission oil
temperature is necessary, as proper fluid level at low
operating temperatures will be below the "ADD"
mark on the dipstick, Figure 27, and proper fluid
level at higher operating temperatures will rise above
the "FULL" mark. Fluid level must always be
checked with the vehicle on level surface, and with
engine running to make certain converter is full. To
determine proper fluid level, proceed as follows:
NOTE: The full mark on the dipstick is an indication
of transmission fluid at normal operating
temperature of 170°. This temperature is only
obtained after several miles of stop-and-go driving.
1 . With manual control lever in Park position
start engine. DO NOT RACE ENGINE. Move
manual control lever through each range.
2. Immediately check fluid level with selector
lever in Park, engine running, and vehicle on
LEVEL surface.
At this point, when a reading is made, fluid level
on the dipstick should be between the add and full
mark.
3. If additional fluid is required, add fluid to raise
the level between the add and full mark.
If vehicle is not driven 15 expressway miles or
equivalent, and it becomes necessary to check fluid
level, the transmission fluid must be at room temperature
(approximately 70°F.).
With fluid at room temperature follow steps 1, 2
and 3 below.
l . With manual control lever in Park position
start engine . DO NOT RACE ENGINE. Move
manual control lever through each range.
2. Immediately check fluid level with selector
lever in Park, engine running, and vehicle on
LEVEL surface.
At this point, when a reading is made, fluid level
on the dipstick should be 1/4" below the "ADD"
mark.
3. If additional fluid is required add fluid to bring
level to 1/4" below the "ADD" mark on the dipstick.
CAUTION: Do not overfill, as forming and
loss of fluid through the vent pipe might
occur as fluid heats up. If fluid is too low,
especially when cold, complete loss of drive
may result which can cause transmission
failure.
NOTE: If transmission fluid level is correctly established
at 70°F. (.9" below full) it will appear
at the "FULL" mark on the dipstick when the
transmission reaches normal operating temperature
(170°F.) . When cold the fluid level is set
1/4" below the "ADD" mark on the dipstick to
allow for expansion of the fluid which occurs as
transmission temperatures rise to normal operating
temperature of 170°F.
C. Boyd
76 Crestmont
East Tennessee
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