Does anyone here know the proper way to check glow plugs? recently we have had some cold days here and I plug my 93 7.3L F-350 in at night so she will start nicely at 5.am to go to work, but at night when leave work she being a real pain in the ***. I asked around for awhile now about checking my glow plugs and I still haven't got a good step by step way to check them, one guy told me to pull them out and dip them in oil and touch them on the battery and if they smoke they work, in theory this sounds logical but glow plugs are only 6volts, and taking them all out is a pain in the ***, another guy told me to use a test light between the battery and the top of the glow plug, would this be logical? A guy told me that even if you did this it doesn't mean the plug is heating up enough to be of benefit to stating. Another guy said check for resistance..... with a multi-meter, Could someone please help!!!???

 

They way I've done it is, unplug all the glow plugs, take a test light and connect it to the positive side of the batt. Then touch the tip of each glow plug. The ones that light up are good.

Using an ohm meter is usless, since it does not put a load on the glow plug.

 

it could be just the glow plug relay has taken a crap. you might want to check out the diesel stop those guys know alot about this stuff. i think i remember reading there is if you get any resistance you are good, but to be sure the plugs are working "GOOD" you have to pull them out and hook up 12V and see if they GLOW. but thats a pain in the *** and somtimes the glow plugs will stay stuck in the head.

 

Like anything else, what are you checking them for...

First use a test light and make sure your GP relay is working...

Next--they are 12 volts...There are several checks to be made for, but not all included...short to grd, open, resistance check, temp check, etc..

The way I would approach it is...if the relay works, then I would just replace all the GP's...they are cheap and you can do it yourself...if you replace just the bad ones, more will go bad...

About the best way to check them is with a ampprobe meter and check the amp draw of each...but here again, if some are bad, you should replace them all...SO does it really have to be checked???

I can tell you this, if I went through all the trouble to remove them and stick them in oil, I would replace them...

Good Luck...

 

what is the expected life of a glow plug?

with a gasser most replace spark plugs every 50,000 to 100,000.

Are you well past the life expectancy of these? You said your truck was a 93. Are these the original plugs?

 

Do you really leave your Truck's engine block heater plugged in all night long? Man, that's 1,500 watts. Imagine 15 100 watt light bulbs being on all night!
I plug the ext cord to my Truck before going in for the night. Then when I get up at 1am, if it is 20 or below that night, I grab the other end of the ext cord and plug it in the house. I start it up at 1:30 to 1:45, and off I go. Mine hasn't failed to start yet.
Anyway, this only heats your oil, (16 quarts is a lot to start cold) and has little to do with your glow plugs. They are heated by a relay that begins when you turn your key to "on"

 

93????

Yes replace all your glow plugs and the relay....If it were mine...Sorry...

 

actually its a water jacket heater, it heats the coolant surrounding the cylinder sleeves. also i have heard about a few of the block heater's cords melting and starting the truck on fire. alot of people just get a heavy duty timer and set it for about 3 hours before they get up in the morning. heres 2 pics of somones rig
pic 1

pic 2

 

Pic 2 (corrected)
WOW!

 

well it worked. the block heater made sure the truck was nice and warm