Home Indiana Agriculture News CountryMark Recommends Draining DEF at the End of Harvest

CountryMark Recommends Draining DEF at the End of Harvest


CountryMark logoCorn Belt farmers will soon wrap up a successful harvest season. With crops in the bins, farmers will turn their attention to combine maintenance. According to  CountryMark, farmers who use combines with Selective Catalytic Reduction (SCR) technology will need to add one additional step to their maintenance list before combines are put away for the season.


“It is our recommendation that Diesel Exhaust Fluid (DEF) systems be drained before newer combines are put away for winter,” said CountryMark Lubricants Manager Dennis Mungle.


Most newer diesel engines are relying on SCR technology to meet federal engine emission requirements, and DEF is a critical component to that technology. As Mungle explains the deionized water in the DEF can evaporate over the winter months leaving behind a solid block of white crystal in the combine’s DEF tank. Once the DEF is in a solid state, it is not easy by any means to return the DEF to a liquid form that the SCR system can use.


“Because evaporation can occur while equipment idles, CountryMark is recommending DEF be drained from equipment that will not be in use for more than four months at a time,” said Mungle.


The best way to drain the DEF tank is to either disconnect the supply line to allow the tank to drain or use a siphon pump to remove the liquid from the tank.  Depending on the model of the combine and the size of the DEF tank, it may also be possible to drop the tank for easier draining.  DEF tanks on combines should be refilled shortly before the next harvest.


“Give the DEF at least one day in the combine before you run it next fall,” said Mungle. “That will get any trace of DEF left behind back into solution.”


For more information regarding DEF and/or combine maintenance, contact your local co-op.