Is there a possibilty that a block may only partialy work, or is it work non work deal? Id think its work or not work, cant think of anyway it could only 1/2 work...
Im asking because the last few mornings,seems like the glow plug light is staying on longer, than in the past....I mean it still fires right up,but before the glow plug was only on for a second, if it all, now it seems like its a good 2-3 secs, and it really hasnt been all that cold of late, lows last week or so have only been upper 20's-mid 30's...
The only thing thats really changed recently is that last weekend i reroute the plug from the wheelweel to the thin opening just under the grill.
I plugged it in one night out of habit like a 1.5 week ago, when it ended up being 47..Also a few weekends ive plugged in it fri night or satnight, and then not started it til monday... is it possible that i did something then, like the glow plug issue some have described when plugging in w/ the cover on??
My variables are no winter cover on, 4-4500 miles on 15-40rotella (its 2 notches dwon from full, do to a loose filter leaking some out) Also my block heater is on a timer to come on about 330 off at 8, as i leave 730-745. I checked and my heater is heavy enough to handle load(its 10amp, 1200 volt)
Im sure this seems tedious to most, but i get paranoid of the dumbest things so bare w/me...Sorry bout the length to...

My trucks outside. 2004 CC/SB LB7, average morning temp of around 10-15 degrees. I keep her plugged in all the time simply because I go in and out and do stuff and it's just easier to always have it plugged in. My glow plugs stay on for a while as well, and the only winter cover I have is a US Gov't issue wool blanket folded so it's the width of the grille, and tucked behind my spotlights I have.

It's not really feasible for your block heater to only partially be working. They are extremely simple in design and do nothing more than heat the antifreeze in your engine to aid in starting. They either work or do not. My glow plug light stays on that long even in the mild winter weather as well. Should be nothing to worry about. The glow plugs stay on for a short time even after the engine has fired as well. The fuel is spayed directly onto them to aid cold weather start up and idle.

I have notice the exact same thing with my truck! I was actually going to post the exact same scenario. My truck plugged in over night and having the oil pan heater on it, the wait to start light was one for 1/2 - 1 second. This AM I unplugged the oil heater. I felt engine and was warm. The temps have been @ 0-15* F. My light now stay on @2-4 seconds even after plugged in.
I find it interesting that this has happened to more than 1 individual.

Ben

I was under the impression that the ecm also based the preheater cycle on the intake temp. If this is correct then even with the engine plugged in, the cold ambient temperature will affect the cycle length.

I'll throw my $.02 in here as well. Down in Texas, we've only gotten into the 20s F and I'll plug mine in that night, before the 5:00 AM drive to work. I too get looong glow plug light, and the engine fires right off, no problem. However, it doesn't seem to be warm, and still takes several miles down the road before I dare turn on the heater. Thank God for those seat heaters!!

klvn8r

What gives? Before my temps at start-up were alot warmer then than now. I thought my block heater was going down the crapper, but it sounds like this is common.

Ben

I forgot to plug in one night and my light stayed on for about 10sec. It started but rough, noisy and lots of smoke. When its plugged in the light is on for maybe 2-3sec and fires right up. Temps outside @ -25 to -30. I have seen a lot of block heater cord ends open circuit and you can't tell. Bend them one way and they make contact. Bend them the other way and they don't. I'd take a close look at the cord end. Doug

Is there a chance that the other end's "plug" is messed up? I haven't looked at it, but I'll presume the block end is a 'freeze plug'. Are these commonly broken/unplugged?

It was 50* here in Northern, IL today and with my rig sitting outside for about 12 hours the glow plug light stayed on about 5 seconds or so and I've seen it go off quicker than that in 20* weather. Oh Yeah and I don't even plug in till its in the single digits.