I have an 07 Classic 2500 LBZ, completely stock, 86,000 miles bought it new. I've never had any issues with the tranny getting hot before 3 weeks ago. Left home pulling 5th wheel (11,000 lbs) after about 6 miles running 45-50, I kept hearing fans running then looked over at tranny temp gauge and was around 240. Pulled off to get fuel and it was up to 250. I let is sit to cool down for a while. I also put it in 4 wheel drive coming out my drive then take it out when I hit the hard top. I assumed it hadn't disengaged completely and thats why the temps got so high. While stopped I reengaged 4wd then disengaged backing up to make sure that it was not in 4wd when I left. Cooled down to about 210 then got on the 4 lane and cooled down to 200 and stayed there. Had tranny fluid and filter changed when I got back.
Left out again last weekend pulling 5th wheel, made it about 150 miles then started up mountain 4 miles 8% grade running 55 started going up again. Stopped after topping the mountain to let it cool, got up to about 230 this time. Stayed there next 10 miles to camp. Return trip Coming back down grade had in tow haul mode, using engine braking tranny temp got to 205 then came back down. Then ran fine at 200 degrees first 170 miles got off 4 lane for last 6 miles running 45-50 and started going up again. Got up to about 240 when we got home.
I checked both cooler lines from tranny and they were hot. Cooler lines were replaced about 3 months ago. Thats about as far as I know on what to check to diagnose. Truck was never straining or working hard even on the mountains. Any ideas would be appreciated.
Left out again last weekend pulling 5th wheel, made it about 150 miles then started up mountain 4 miles 8% grade running 55 started going up again. Stopped after topping the mountain to let it cool, got up to about 230 this time. Stayed there next 10 miles to camp. Return trip Coming back down grade had in tow haul mode, using engine braking tranny temp got to 205 then came back down. Then ran fine at 200 degrees first 170 miles got off 4 lane for last 6 miles running 45-50 and started going up again. Got up to about 240 when we got home.
I checked both cooler lines from tranny and they were hot. Cooler lines were replaced about 3 months ago. Thats about as far as I know on what to check to diagnose. Truck was never straining or working hard even on the mountains. Any ideas would be appreciated.