Re: Problem with my Ford F350 transmission pulling heavy load.
You may be overheating the fluid and it's boiling over. There is only a
minimal of air pressure differential in the transmission, which the vent
should handle. Some older 4X4 had the vent attached to a hose that was
attached higher then the transmission to prevent water from entering. It
could also be you are approaching an angle limit in which the fluid level
gets near the vent.. I would say it may be a combination of overheated
expanded fluid, and the angle that you are climbing. If you add a good
volume oil cooler, and don't overfill the transmission, your problems
should go away.
"Todd" <email@example.com> wrote in message
> Hi all,
> I have a question regarding a problem I am having with my 1999 Ford
> F350. It is a 4x4 duallie with the powerstroke diesel. I bought this
> truck used and did not know it had some performance enhancements added
> to the engine and automatic transmission. Here is my problem:
> I occasionally tow heavy loads. Usually I don't have any problems; the
> truck is a beast and never breaks a sweat. However, twice now I have
> towed a heavy load (once was a 10k# tractor, and the other time a 9k#
> 5th wheel) and the transmission dumped a bunch of transmission fluid
> on the ground, presumably through the vent line.
> This has occured under specific conditions. In both cases, I was
> approaching a steep incline on gravel, and decided to put the truck in
> 4x4 mode to climb the grade. In both cases, the grade was about a
> 15-17% incline. I stop the truck, put in 4x4 mode, then start up the
> grade. THe first time it was in reverse (and 4 wheel low), the second
> time in first gear going forward. After about 30 seconds, I smell
> transmission fluid and look under to see a waterfall of fluid from the
> The first time, I took it in under the extended warranty and had the
> transmission replaced. However, now it has occured a second time with
> a 6 month old transmission, so I am obviously thinking it doesn't have
> to do with the transmission being bad.
> The transmission has a Banks Transcommand installed, and the engine
> has a Dyno Sources chip, which (according to the website) adds 75hp
> and 162 lb/ft of torque. It also modifies the shifting settings.
> I talked to a guy at Aamco, and he thought the dumping of fluid was
> due to too much hydraulic pressure in the transmission, and the
> pressure released through some sort of valve. This makes a bit of
> sense, since the transcommand increases hydraulic pressure, the
> increased torque, ~10k pound load, starting up a reasonably steep hill
> from a dead stop, etc. I am just not convinced, and I would expect the
> transmission to handle a load like that without dumping 3-5 quarts of
> fluid on the ground.
> The AAMCO guy said that no harm was done and to just replace the
> fluid. ??? (On a side note, I was amazed a transmission guy told me my
> transmission was fine after dumping all that fluid... easy money...)
> What do you folks think? Is this common or reasonable? Anything I can
> do to fix it? Should I ditch the chip? I would rather not, as I love
> the performance enhancements... Do you think the transcommand and the
> engine chip are conflicting / overboosting?
> My current plan is to add a transmission oil cooler, and some gauges
> for oil temp, pyrometer (exhaust temp), etc. I am looking for more
> adgvice to make the truck more bulletproof.
> Maybe I am just asking too much of it... pushing a 10k# trailer up a
> hill with a 8400 pound truck may be too much for the Ford
> Thanks for any help,