I'm curious- is there any data- real proof- that heating the plugs longer is harmful to them? I doubt that there it is. A tight, high compression engine is going to start quicker, so on these newer tractors, it may be difficult to determine if they start quicker because they are new, or because the glow plug system is better. On my B7100, it wouldn't start, at any temps, without glow plugs (cold engine). 8 or 10 seconds in summer weather, it would fire right up. Cold/Winter weather- 20-30 seconds, minimum. The V1702 in my Bobcat- a minimum of 30 seconds, and the instructions are to heat the plugs for 45 seconds. So, not every diesel is the same for the time to heat the plugs. Yet, I'm not replacing glow plugs in our equipment. As a side note, my JD 790 doesn't use glow plugs, but an intake heater (like a Cummins). I've never owned a diesel that starts faster.
In my opinion, I'd rather replace some glow plugs at some future time, than barely start a cold engine or overwork a starter. I can not imagine that over the years, an extra 5 or 10 seconds of heating is going to change the life of the plugs.
I tried to shorten the time and all I would get would be black puffs of smoke and sputters for what I thought was a long time. Since I have used the longer times it starts right up unless the fuel is jelled/frozen (happened once and not since I have used the Diesel 911).
