by Begle1 » Tue Feb 27, 2007 4:26 pm
If you look at your engine, there are two little 4-inch squares stacked on top of each other that the intake horn mounts into. Each one is a ~1200 watt heater element. Below 60 degrees they engage for a few seconds before you start your engine (that's what's happening when the "Wait-to-Start" light is on), and then they'll continue to cycle until either the engine is warm or you reach a pre-programmed speed (I've heard both 25 and 30 MPH as shut-off points). They heat the air going into the engine so that is starts better and doesn't make massive amounts of blue-white smoke until you warm up.
The grids are pretty indestructible and are over 500 times more effective and trouble-free than glowplugs. Only warning I've ever heard with regards to them is to not operate an aftermarket radio head unit while they're cycling, and to not spray ether into the intake lest it explode. Other than that the voltage drop doesn't seem to hurt anything.
1990 D-250 Regular Cab: Tweaked injection pump, built transmission, a cataclysmic charlie foxtrot of electronics, the most intense street-ran water injection system in the country, and some more unique stuff.