Tranny temps

[wargle]

Driving home one night last week, my tranny temp on my Scan Gauge stayed around 171*. Outside temp was 41*. My speed was 55, unloaded. Truck has 77,000 miles is completely stock and the transmission was flushed at 54,000 miles. I've only had this truck for a month. Is this temp normal for the circumstances stated? I plan to tow my 8,000# 5th wheel starting in May. Am I going to have to upgrade/replace my stock cooler or something more $drastic$?

[BIG Laing]

Originally Posted by wargle

Driving home one night last week, my tranny temp on my Scan Gauge stayed around 171*. Outside temp was 41*. My speed was 55, unloaded. Truck has 77,000 miles is completely stock and the transmission was flushed at 54,000 miles. I've only had this truck for a month. Is this temp normal for the circumstances stated? I plan to tow my 8,000# 5th wheel starting in May. Am I going to have to upgrade/replace my stock cooler or something more $drastic$?

I would not be worried one bit! Tranny Temp

[drewactual]

our transmissions have a thermostatically controlled bypass valve that only allows 10% of the fluid to circulate through the cooler when the transmission is below 165*, and sends the 90% back through the trans un-cooled... this is why your transmission likes to stay around the 170* mark when not being worked hard.. it will reach 165* quickly, and then that valve goes into action, fluttering open and closing, sipping cooler fluid as needed to keep you around the 170* mark..

you're right on the mark, my man..

it's when you're working the crap out of it and have reached the circulation-to-heat exchange @ 100% rate, and still climbing in temperature when you have a problem.. and that is a bad problem to have!!

here is a good chart that shows what happens to transmission fluid, soft parts and hard parts at various intervals.. you'll see that the 170* is prime.. anything below 140* is also hard on a transmission, but generally only that it won't flow enough.. it will buck and such under such circumstances, but even then- modern transmissions w/ electronics controlling them generally won't allow o/d or t/c lock-up unless you've reached a certain temperature range..

[wargle]

Outstanding! Thanks for all your help. I'm learning as I go and it's info like this from you histhat makes this forum the best.

[wilsonw2]

Drewactual u seem to know a lot about transmissions. U a mechanic or mechanical engineer?

If u are or aren't, I'm sold and impressed! Thanks for the spread of wisdom.


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[drewactual]

Originally Posted by wilsonw2

Drewactual u seem to know a lot about transmissions. U a mechanic or mechanical engineer?

If u are or aren't, I'm sold and impressed! Thanks for the spread of wisdom.


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dude, I slept at a holiday inn express last night...