Hi searay
The "normal operating temperature" of
a rear wheel drive transmission of
the type found in domestic vehicles,
is 160° to 200° with variances of ten
degrees being typically acceptable
depending on driving conditions, and
duration of the variance. The average
narrow range of function is closer to
160°-180°
As long as the temperature does not stay
elevated for too long damage should
not result. Too long being more than
a few minutes. Extremes in transmissions
can occur from very high or very low
ambient temperatures. When combined
with hauling, trailering, racing, or
driving over hills and mountains, very
large swings in operating temp can
occur. Temps as high as 300° can happen.
The damage that happens to a transmission
from overheating is typically a result of
loss of lubrication or extreme pressure.
The loss of lubrication is due to coking
or carbonizing of the petroleum based
transmission fluid. When these solids
form out of the fluid, they degrade the
ability of the fluid to protect metal
surfaces from friction. The metal surfaces
with no protection will eventually fuse,
literally welding together. Internal
parts may even fracture due to thermal
shock. Seals begin to deteriorate at
approximately 250° which can create
leaks.
Also extreme operating temperatures
can raise the transmission fluid pumping
pressures which will in turn blow out seals,
or gaskets, and possibly causing warpage of
internal components. The seals will have
been weakened by the extreme temps at
this point, and will be more susceptible
to pressure variances.
Temperature abuse of transmission
fluid and in some cases, internal
parts, is cumulative. Meaning, if you
run the transmission hot frequently
each subsequent overheating will be
more damaging.
Many factors will ultimately decide
how much abuse a transmission can take.
Ultimately the level of temperature vs
amount of time at that temp vs last
maintenance/fluid change will determine
damage caused. Assuming a clean fluid
changed regularly, no mechanical problems
with the transmission, such as bad clutches,
bands, convertor, etc... I would say
any "out of spec" temp for more than
15-20min would begin to cause damage
that would shorten overall lifespan,
and even possibly cause it to cease
functioning. Temps as high as 350°
can cut fluid life down to just a
few tens of miles before total failure.
I hope this answer will be adequate for
you. I did not pull your vehicle's temp
range out of a book specifically. The
numbers I quoted are based on many
years of automotive repair work. The
temperature ranges of transmissions are
typically based on the fluids used,
which are very close in operating
specs when it comes to petroleum based
types.
I have some websites that corroborate
the info. I also included a few pages
with transmission temp gauges for
comparison. If, as part of your answer
you would like for me to get the
specific temperature answer from the
local Dodge dealer, I can do so in the
afternoon. Just ask for a clarification,
please.
[ http://216.239.33.100/search?q=cache:eiPidqcGoLAC:www.amsoil.com/products/atf.html+transmission+fluid+temperature&hl=en&ie=UTF-8
]
[ http://www.goa-northcoastoil.com/tips/atfchnges.html ]
this info looks VERY close to the prior page:
[ http://autos.yahoo.com/repair/results/ques123.html ]
[ http://www.hmppd.com/faqtemp.asp ]
[ http://www.geocities.com/MotorCity/Downs/1708/transmission.html ]
A nice page on transmissions
[ http://www.familycar.com/transmission.htm ]
-Search technique-
{my own life experience} and
keywords:
transmission fluid temperature
[ ://www.google.com/search?q=transmission+fluid+temperature ]
this is my first "official answer"
as a researcher, I hope I provided
the info you sought,
-AI |
Clarification of Answer by
alienintelligence-ga
on
03 Aug 2002 23:19 PDT
Hi searay,
Thank for the rating, I appreciate
it alot with this being one of my
inaugural questions.
Its 11pm, so I will have to try
for the specific temperatures
when places are open again. If
for some reason I can't find it
on Sunday, I'll hunt someone
down for sure at the beginning
of the week.
thanks again searay, I hope
we’ll be seeing you here again
with future questions,
-AI
|
Clarification of Answer by
alienintelligence-ga
on
05 Aug 2002 15:22 PDT
Hi searay
Well I feared I wasn't going to get
this answer finalized by the dealership.
It took 3 calls to get someone that
came close to knowing what they were
talking about.
The gentleman I finally spoke with was
in the service department and he was
billed as their transmission expert.
He was also very willing to help me
diagnose your transmission. Shame it
wasn't here with me.
He stated the working range for the
truck's transmission operating temps,
to be 250°-275°. I asked him if this
wasn't a bit high. He said yes, I'm
giving you a high load condition.
(Hill climbing, towing, rough duty,
traffic) Anything more than simple
road cruising (with average ambient
temps in the range 70s-80s) would give
you a range of 225°-275° and anything
above that being detrimental. He said
he quoted the high range first because
he could tell I was concerned about it.
I thanked him and asked about normal
driving down an open highway conditions.
He confirmed that in average operation
that did not involve start/stop or
high outside temps, towing, hills,
etc... you would see a temp range
of 160° while the transmission is
warming up, gradually going up to
180°. If the ambient temps go up,
then the operating temperature will
follow. The condition of transmission
internals and fluid quality can affect
this by a slight amount too.
He confirmed that high fluid temp
can be linked internally to fluid
port blockages, cooler blockages,
filter blockages, convertor not
properly locking, or just being worn
out. Other varied slippages can also
increase the operating temp, and
reduce the overall life expectancy
of the transmission.
It was nice talking to this guy. I felt
a reassuring sense of capability.
I hope this information serves you
well. Thanks again for the rating
you gave me.
cheers
-AI
|
