...I HAVE to let me sprinter idle...
I had no idea you were Irish. Top o' the mornin' to ya!
When you idle, it's best to use an idle stick on the gas peddle to increase the engine RPMs to between 1200 and 1800, the higher the better, in order to keep the heat and pressure high enough to keep the EGR valve working properly. If it idles for long periods at low RPMs, the EGR valve remains mostly wide open letting too much exhaust gases into the engine, which causes soot buildup, which then mostly gets blown out the back when you start rolling. The massive amounts of smoke looks bad, but will clear itself out after a few miles of driving.
Idling a Sprinter is bad for the engine, but it's not nearly as OMG-Never-Do-That-Bad as some would have you believe. The primary consequence of idling is having to replace the EGR valve twice as often as you otherwise would. The turbocharger does need a minimum amount of boost pressure to maintain the condition of the seals, so extended idling could result in oil consumption and premature seal failure of the oil cooler and injector pump seals, which can lead to expensive repairs if leaking oil gets into the high pressure fuel injector pump ($1300) and damages it, like it did mine. But those seals will eventually go bad, anyway, and if you idle you may end up replacing the seals and/or the injector pump at 300,000 or 400,000 instead of 500,000 or 600,000 miles.
There are added problems with idling the newer Sprinters with the DPF, as it will need cleaning or replacing sooner than otherwise with idling.
At low idle you'll burn about a third of a gallon per hour, at the expense of having to replace the EGR valve early and other possible (probable) expenses later, and at high idle you'll burn a gallon an hour. Either way the expenses end up being roughly the same. At $4 an hour idling, even a rudimentary cost analysis shows that an Espar heater is far more cost effective in both the long and short term (and in the long term is quite a bit cheaper than propane heaters, not to mention safer). It seems like a lot of cash to outlay all at once, but an Espar heater should be near the top of your list of things to get for the van, as it pays for itself the first winter and then keeps paying you back after that.
