GMC transmission issue
I'm not sure where to post this, but we have a 2012 GMC 3500 Sierra and a Cyclone 3010 5th wheel 35 foot toyhauler. Lately we have been experiencing "clunking" when the transmission drops a gear, ...
Forum Discussion
wintersun wrote:
With Tow Haul mode the transmission runs cooler, which is a key part of the function of this mode. Last week with a heavy load going through the desert with temps over 100 degrees outside and going from 3000 feet to over 7000 feet of elevation the trans temp in my 2011 Duramax/Allison never went above 172 degrees. The GM trans coolers are the best you can get.
I have a 2012 Dmax/Ally and found out from some very knowledgeable people over on the DMax forum recently that the new 2011+ Allisons run so cool is because they run lower line pressure than previous Allisons and not due to the factory tranny cooler which was described as "average" at best. There are better aftermarket ones out there but really not needed due to the lower line pressure and resulting lower temps these things see in stock form even pulling heavy loads up steep grades.
