GMC Sierra 1500 Towing Advice
Hello, First time poster long time reader. I have a 2012 GMC Sierra 5.3 6speed with 3.42 gears. I have the tow package with trans cooler. I read these forums for a long time and tried to bu...
Forum Discussion
wmoses wrote:Nvr2loud wrote:
The only real problem is the 6 speed transmission (the tranny is great but the computer no so much) It constantly tries to reach 6th gear and the transmission temperature goes way up. If I select manual mode and keep it confined to 4th and under the transmission temperature goes way down, it pulls easily up grades, and I hardly feel the trailer. The engine RPM is much higher then daily driving, but it is still okay. On long flats I allow it into 5th, but never 6th... gear hunts too much and temperature goes up again.
On the pull I mentioned in the post above I had it on cruise control, tow mode and with no manual lockout. Tranny temps hit 190 deg.F IIRC. Outside temp was 84 deg.F. Good to know about your experience locking it into 4th or 5th and its effect on tranny temps. No hunting of gears really - flats about 1900 rpm, slight grade jumps top about 2500 or so then more serious grades causes the jump to 3400 rpm. Don't think the engine ever went above that when towing. I think the tranny computer does a good job. Don't know if it makes a difference but I replaced both my tranny and rear differential oil with synthetic.
What were those high temps anyway, and how high did your revs go in 4th?
I shift down to 2nd for steep grades and run at 4500 RPM
I attempt to NEVER let the engine drop below 2500 RPM when towing my trailer, typically aim for around 3000 RPM unless it is nice and flat, then I will let it shift up and drop down below 2000 RPM.
My transmission runs around 85 C (194 F) when hunting gears and 65 - 70 C (158 F) when I lock-out the higher gears.
I'm averaged 19 Litrers per 100 km for a round trip of 600 km's for this past weekend. That converts to about 12.4 mpg for 375 miles
