We have had a number of our Blue Bird/Cummins buses go into limp mode during the cold weather (-20 to -35C) It appears that the DEF if freezing and the heater cannot melt the ice block fast enough to keep up with the usage. I called our BB dealer. The response was: "We know there is a problem and are working on a solution, but it could be a month to get some results." The suggestions were: During cold weather idle the bus for at least one hour to allow the DEF to thaw. Wrap the DEF tank in an electric blanket to keep the DEF from freezing. Install a heating pad safe for plastic tanks. Send a jug of warm DEF with the driver and have them add a couple of quarts if they have a problem.
I hope that in a months time the problem will go away on it's own till next year.
I'm not sure of the BB but I know that some vehicles with DEF have tank heaters that come on when sitting if the temp drops. If there is a heater there is probably an issue with that.
We are dealing with the same issues here. As far as the bluebirds go we service 5 customers [with def tanks]and only had one towed this year. Last year was a revolving door for frozen buses and it was all the newer ones. The old 7.3 and 6.0 just go in cold weather. Bascily talked with the one owner last week and he is running a battery blanket and having his driver only fill the tank no more that 45% so there is a lot less fluid to keep warm. He has had zero issues this year and it has been below 35 c a few times. It seems to work. We had -40 couple 2 weeks ago and only had this one blue bird towed [he is installing a blanket at this point]and 2 c2 towed with frozen tanks as well. These are the first c2 to get towed in so thinking they are all vulnerable to a frozen def tank. We actually had a customer with a 2013 gm truck with a welder on and he had is def eliminated because he could not operate up north in the cold weather reliably. Only thing he has lost all his warranty. Just can't wait for this stuff to get a few years old , its going to be expensive to fix and the owners are not going to be happy.
DEF fault
Posted - 02/20/2014 : 8:40:51 PM
