LBZ heat soak and towing with MORE POWER
Much has been written and discussed on this topic, but until you have experienced it first hand, its someone else's problem...
In the last three weeks, I have had the opportunity to traverse 15 states with widely varying temperatures, altitudes, and loads. I found that my 2006 K3500 SRW LBZ was not immune to the heat soak issues experienced by others that tow moderate to heavy loads, and use aftermarket tow tunes. Here are my observations:
The classic scenario is low speed grade climbs with a GCVW of 20K# or better, A/C on and outdoor temps of 70F or above. In most cases, the soak will start with water temps rising to 220 and above. The fan should be in at this point, but isn't yet. Transmission temps must follow, even if there isn't internal slip creating the heat - remember its going to exchange heat in the radiator for good, or for bad.
- I was never able to push the truck to a heat soak condition with the stock OEM tune. That isn't to say that temperatures out of range aren't possible - they are - but nothing where the truck simply 'tips over' due to temps and cannot continue;
- The problem starts at the turbo, and works its way through the other systems. It is further compounded by a fan clutch that engages much, much too late to keep the problem in check;
- Even 'mild' towing tunes by three manufacturers, under the right (wrong) conditions can initiate a heat soak. The key is to stop the soak, before it becomes critical, by either reducing load and reducing fuel rate. (Your right foot, or removing the performance tune in favor of stock.)
The ability to immediately pull over and idle back to acceptable temps is important if you sense that your truck is on the way to the 'tipping point' and won't recover with fan clutch engaging at 230-240. Sometimes it simply depends on how much mountain grade is left in front of you. Returning to your stock tune always requires shutting off the truck. Do your engine a favor and let it idle back down to acceptable temps before shutting it off in these conditions. Your turbo bearings will thank you...
MY RULES OF THE ROAD FOR TOWING WITH AFTERMARKET TUNES
- Stock tune must always be available - i.e. don't leave that tuner, ECM, or ability to 'return to stock' at home.
- A/C adds significantly to the heat load - if you can live without it, roll down the windows in the mountains and leave it off.
- A light foot (lower ground speed) can help to keep heat in check. Howevever, too slow can also introduce soak due to not enough airflow over the cooler stack. Try to maintain 1800-2200 rpms, and accept your ground speed for the grade.
- If water and tranny temps are both at 250 and climbing, you're not going to recover gracefully - unless you are cresting the top of the hill. Don't wait for the meltdown, pull over, IDLE THE TRUCK back to acceptable levels, return to stock tune.
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Originally Posted by Mark Rinker
