DOWDYL350 Report post Posted March 10, 2012 When do you use the engine block pre-heat switch? Share this post Link to post Share on other sites
wolfe10 Report post Posted March 10, 2012 Assume you have a diesel. Let's cover two approaches: "Best Practices" is to use it at 40 degrees F or below. If around 40 for perhaps one hour. "When you must use it" varies with engine, but the further below freezing the more it helps. The colder it is the longer you would leave it on. As far as how long to run the block heater, most are around 1000 watt heaters. One to two hours is generally enough. I have seen people leave them plugged in overnight, but that is a waste of power unless you are in Arctic conditions. Brett Share this post Link to post Share on other sites
Janvlen Report post Posted March 10, 2012 If you must use a block heater, then it should be "on" for a minimum of 4 hours. Even with a gas engine, a 4 hour minimum is considered normal. A better solution is to buy a timed unit, wherein the heater is on for 2 hours and off for 2 hours. The best solution is to buy a temperature controlled unit that when it is required, runs on the 2 hour cycle. These guidlines are normal in southern (sounds like an oxymoron, doesn't it?) Canadian winters. In the colder weather up north, automatic temperature controlled oil fired coolant heaters are employed. Better to come south....... Share this post Link to post Share on other sites
wolfe10 Report post Posted March 10, 2012 The 4 hour minimum or 2 on/2 off may very well be great advice in Canadian winters, but if talking about near freezing temperatures (in the 30's-- yes 30 degrees F ABOVE zero) no need for that much time/ energy use. Yes, you are heating up 800 to 1500 pounds of engine. But you have a 1000 watt or so heater. Share this post Link to post Share on other sites
five Report post Posted March 16, 2012 I called Cummins with this question...40 degrees or lower it should be turned on. FYI, my ISL weighs over 1,700# according to the manual. Share this post Link to post Share on other sites
Guest BillAdams Report post Posted March 17, 2012 Turned on and turned on for how long are both questions that need to be answered. I know that the block heater in my coach "can be" turned on and left on as it is rated for continuous duty. I suspect that no one would want to use this option. So, if that's the case, how long does it take for the block heater to have enough effect on your engine to be effective? Generally, I try to turn mine on at least 2 hours before I want to start up and have found this to be sufficient. YMMV as my engine is quite likely not even similar to the engine in your coach! Share this post Link to post Share on other sites
