Attention: TDR Forum Junkies We hitched up the toybox last Friday and set off to Kennedy Meadows weighing in right at 20000# with full fluids, gear, and motorcycles. This was the first time to this location which is in the South end of the Sierra's and has a notorious tight and turning grade called 9 mile canyon which climbs 4000' in the 9 miles between desert floor and the treeline. On this trip I learned a couple of things.
First, the Cummins can overheat. Not on normal interstate grades though, as we were easily doing 65 across the 100 degree desert with AC on and running at about 200 on the temp guage and 180 on the transmission. However, when it came to 9 mile canyon, I did not think to turn off the AC. I pulled ahead of our friends in thier class A and was going to show him just how great this CTD runs, and I think I overdid it. I tried to run the grade in 2nd gear, and the transmission started heating fast, eventually ending up at 280 and then all of the lights came on at once. Trans temp light first, then the engine temp shot up to 240 almost instantly, and this is in the middle of an 8% section with S-turns and no shoulder. I immediately recognized the danger so I stopped in place and cranked the heater, then dropped to 1st gear and chugged my way up the rest of the hill. Both the transmission and water temp cooled down to normal temps very quickly in this mode. I surely hope no permanent damage was done, and based on how it has run since I don't think it did. It was surprising to me how quickly the temps went from normal to outrageous, seeming to feed off the other and increase in a sharp curve.
Second lesson, same grade just 2 minutes later. Now that the temps are back to normal and my buddy in the class A is way ahead of us, I start smelling something funny. I glance over the guages and notice that the FP is 0 ! So again we stop in the middle of the road on this nasty grade and pop the hood. My vinyl FP line and 1/4" vinyl sheath had melted all the way through by rubbing against one of the brake lines coming from the proportioning valve. Luckily I used a needle valve in the installation and one burnt arm later the leak was stopped. BTW, even with a snubber and a barely open needle valve, that leak must have been 1/2 gallon per minute - quite a bit more than I would have expected.
I learned a few things on this trip, and it surely could have been worse. I'm not sure that I will attempt that 9 mile canyon again without a better transmission/exhaust brake. Going down the grade was as exhausting as riding the dirt bike through the technical forest trails, but I think that mama will buy into the transmission upgrade after that trip.
BTW - anyone know where to get a pre-fabbed SS FP line quickly ?
First, the Cummins can overheat. Not on normal interstate grades though, as we were easily doing 65 across the 100 degree desert with AC on and running at about 200 on the temp guage and 180 on the transmission. However, when it came to 9 mile canyon, I did not think to turn off the AC. I pulled ahead of our friends in thier class A and was going to show him just how great this CTD runs, and I think I overdid it. I tried to run the grade in 2nd gear, and the transmission started heating fast, eventually ending up at 280 and then all of the lights came on at once. Trans temp light first, then the engine temp shot up to 240 almost instantly, and this is in the middle of an 8% section with S-turns and no shoulder. I immediately recognized the danger so I stopped in place and cranked the heater, then dropped to 1st gear and chugged my way up the rest of the hill. Both the transmission and water temp cooled down to normal temps very quickly in this mode. I surely hope no permanent damage was done, and based on how it has run since I don't think it did. It was surprising to me how quickly the temps went from normal to outrageous, seeming to feed off the other and increase in a sharp curve.
Second lesson, same grade just 2 minutes later. Now that the temps are back to normal and my buddy in the class A is way ahead of us, I start smelling something funny. I glance over the guages and notice that the FP is 0 ! So again we stop in the middle of the road on this nasty grade and pop the hood. My vinyl FP line and 1/4" vinyl sheath had melted all the way through by rubbing against one of the brake lines coming from the proportioning valve. Luckily I used a needle valve in the installation and one burnt arm later the leak was stopped. BTW, even with a snubber and a barely open needle valve, that leak must have been 1/2 gallon per minute - quite a bit more than I would have expected.
I learned a few things on this trip, and it surely could have been worse. I'm not sure that I will attempt that 9 mile canyon again without a better transmission/exhaust brake. Going down the grade was as exhausting as riding the dirt bike through the technical forest trails, but I think that mama will buy into the transmission upgrade after that trip.
BTW - anyone know where to get a pre-fabbed SS FP line quickly ?
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