Question about glow plug/light

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Dec 9, 2011 | 12:28 PM

draboo

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Question about glow plug/light

After patiently waiting for that little "pigtail" glowplug light to go out, does that mean that the plugs stop heating up..or does it mean that the plugs are hot enough to start it and the plugs keep getting power?

Reason for this question: Another thread mentioned that some folks cycle the key assuming that when the light goes out, the power to the plugs has stopped and cycling heats up the cylinders more for better cold weather starts.

I have no idea which is correct, but, considering how complex the whole freakin' electronics system is, I m guessing there is really no need to cycle the key to help with cold starts, the 'puter with all of it's vast wisdom takes care of this situation.

Dec 9, 2011 | 12:44 PM

zhilton

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From: Claremore, OK

Quote:

Originally Posted by draboo

Nope, they keep going for 2 minutes after you turn the key to the "ON" position. Even after the "pig tail" goes out...they're still going. Not sure who's idea it was (Ford or Navistar) but the alternator doesn't start charging until after the glow plugs go out. So your truck is running for about 2 minutes on the batteries. That's part of the reason good healthy batteries are a must in these trucks.

Quote:

Originally Posted by draboo

Reason for this question: Another thread mentioned that some folks cycle the key assuming that when the light goes out, the power to the plugs has stopped and cycling heats up the cylinders more for better cold weather starts.

All your doing by cycling the key/glow plug light is buying more time for the glow plugs to heat the cylinders. Not gaining anything as far as "giving the engine an extra shot of glow plug heat"...just longer soak time. Remember, diesel engines need fuel, compression & heat to run. The glow plugs give the engine the heat they need to light the fuel off.

Dec 9, 2011 | 12:47 PM

Snuggyworm

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From: Houston, TX

well said zhilton!

Dec 9, 2011 | 03:30 PM

draboo

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So, contrary to my belief, cycling the key does help with starting in colder weather.

Dec 9, 2011 | 04:59 PM

Rusty Axlerod

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From: L.A. (Lower Alabama)

Not really, read post#2 again. It just resets the 2 min timer so to speak.

Dec 9, 2011 | 05:22 PM

tharepairguy

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It would only help it start better by cycling the key if your gpcm/glow plugs are defective or near death. When I changed all mine out, the research I did to make sure I put the best ones back in, was something like this. The factory plugs turned out to be the best, duh. They are rated to heat up to max temp within a certain amount of time. Can't remember what the time was on the factory plugs...

Dec 9, 2011 | 06:14 PM

cheezit

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From: N. Fort Worth, tx

i disagree, there is a 2 min timer, wait 1.5 min then cycle the key the truck will start better with less effort. the longer the cycle the hotter the cyclinder.
my .02 worth

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Dec 9, 2011 | 10:04 PM

draboo

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Quote:

Originally Posted by cheezit

i disagree, there is a 2 min timer, wait 1.5 min then cycle the key the truck will start better with less effort. the longer the cycle the hotter the cyclinder.
my .02 worth

Now THIS makes sense!