Glow plug testing question
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Cargo Master
Joined: Dec 2011
Posts: 2,750
Likes: 4
From: Pecatonica, IL
Glow plug testing question
Hey All!
This isn't for my truck but one I'm going to be working on tomorrow. Its an 88 F-250 7.3L so its got the new system.
I know the method for testing glow plugs, but my question is I don't have a good test light, so I was going to ohm them insted. What am I looking for for a reading? I know that infinate would mean a burned out glow plug.
Guy is complaining of a real hard start in the morning. WTS comes on very briefly I believe (ill have to verify that) I think he may have more going on than glow plugs but I don't know for sure. Possibly some air intrusion. Its only when the truck sits like over night, after the first start it will go no problem for the rest of the day.
I have already found (and read) some very helpful threads here. I'm ready to wire a toggle switch to it if the controller is faulty, but I thought it would be good to check the health of the glow plugs first.
Anyways pry usless babble, thanks guys!
This isn't for my truck but one I'm going to be working on tomorrow. Its an 88 F-250 7.3L so its got the new system.
I know the method for testing glow plugs, but my question is I don't have a good test light, so I was going to ohm them insted. What am I looking for for a reading? I know that infinate would mean a burned out glow plug.
Guy is complaining of a real hard start in the morning. WTS comes on very briefly I believe (ill have to verify that) I think he may have more going on than glow plugs but I don't know for sure. Possibly some air intrusion. Its only when the truck sits like over night, after the first start it will go no problem for the rest of the day.
I have already found (and read) some very helpful threads here. I'm ready to wire a toggle switch to it if the controller is faulty, but I thought it would be good to check the health of the glow plugs first.
Anyways pry usless babble, thanks guys!
i ain't rite
Joined: Mar 2005
Posts: 65,561
Likes: 5,596
From: Marlboro Mental Hospital.
if i remember correctly a good glow plug will ohm out around .5 ohms, and anything over that is basically bad.
i normally check for power going to the glow plugs. if i have power at the glow plug at first key on, i don't even bother testing them and just put a set of new ZD-9's in it.
i normally check for power going to the glow plugs. if i have power at the glow plug at first key on, i don't even bother testing them and just put a set of new ZD-9's in it.
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Cargo Master
Joined: Dec 2011
Posts: 2,750
Likes: 4
From: Pecatonica, IL
Tom!! Wasn't expecting to see you over here! I figured they were about the same as our powerstrokes but it doesn't hurt to be sure. I'll be sure to let everyone know what I find.
Flainn that does sound like a great idea. I don't know any previous history on the truck, but you can rest assured that this gp system has seen some neglect and pretty sure it hasn't worked right in a while.
If only you could meet the guy with this truck. He's quite a character completely harmless. I think he has Budweiser interveneoisly running through his system at all times. The truck isn't much to look at but he loves it and wants to keep er on the road. We'll get em going.
Flainn that does sound like a great idea. I don't know any previous history on the truck, but you can rest assured that this gp system has seen some neglect and pretty sure it hasn't worked right in a while.
If only you could meet the guy with this truck. He's quite a character completely harmless. I think he has Budweiser interveneoisly running through his system at all times. The truck isn't much to look at but he loves it and wants to keep er on the road. We'll get em going.
i ain't rite
Joined: Mar 2005
Posts: 65,561
Likes: 5,596
From: Marlboro Mental Hospital.
i am like flies on cow dung, or hookers at a political convention. you never know when or where i will show up, but i will get there sooner or later.
Senior User
Joined: Jun 2010
Posts: 406
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From: NW Ga
Ohm meter has to be real good. My wires on my read .4 ohms so it isnt good enough even though its suppose to be good. Its a Crapsman from Sears. Test light works best and is idiot proof.
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Lead Driver
Joined: Apr 2008
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0 ohms is bad 2.5-5 is usable. The test light will still light up with a weak GP. If he has "WTS" then the controller sounds fine, especially that it is a brief WTS. Sounds like a few burnt GPs. Use beru / motorcraft replacements. O'Rielly's has them for a reasonable price.
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Cargo Master
Joined: Dec 2011
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From: Pecatonica, IL
Ok!
Got it in the shop this morning, I'm going to venture a guess and say the problem is the glow plugs. Light is brief, checked a couple with a ohm meter and didn't get a good reading, your right its hard to get a good reading. And my ohm meter is a cheepy so the odds are against me.
Checked the relay, its kicks on and then right back off again. Going to try changing the glow plugs and see what happens.
Got it in the shop this morning, I'm going to venture a guess and say the problem is the glow plugs. Light is brief, checked a couple with a ohm meter and didn't get a good reading, your right its hard to get a good reading. And my ohm meter is a cheepy so the odds are against me.
Checked the relay, its kicks on and then right back off again. Going to try changing the glow plugs and see what happens.
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Cargo Master
Joined: Dec 2011
Posts: 2,750
Likes: 4
From: Pecatonica, IL
An Update:
Got the new glow plugs in, had to splice in a couple of connectors as they were burnt.
Got them all in and did the same thing. Clicked on and then off. So I changed the relay, still the same thing. So the controller must have been toast. I could have swore I was getting a WTS light, but upon further inspection, there was not.
So I did the switch mod. Seems to work well. Only question is what is the max time you can run the glow plugs? I was told no more than 10 seconds. Just wondering cause it still started kinda hard, but it did start. I think he has some other issues as well, noticed a couple of fuel leaks. But I didn't fix those, just what he wanted fixed.
Thanks again everyone for all your help!
Got the new glow plugs in, had to splice in a couple of connectors as they were burnt.
Got them all in and did the same thing. Clicked on and then off. So I changed the relay, still the same thing. So the controller must have been toast. I could have swore I was getting a WTS light, but upon further inspection, there was not.
So I did the switch mod. Seems to work well. Only question is what is the max time you can run the glow plugs? I was told no more than 10 seconds. Just wondering cause it still started kinda hard, but it did start. I think he has some other issues as well, noticed a couple of fuel leaks. But I didn't fix those, just what he wanted fixed.
Thanks again everyone for all your help!
Lead Driver
Joined: Apr 2008
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Someone posted a table, it goes up a couple seconds for every 40* colder than 111* or something weird. Mine in the 92 comes on for 8 and it fires up good (suspecting a tired GP or two light is shorter cranking is longer but still starts good) Our IH service truck with a 6.9 you HAVE to glow 25-30 seconds or it wont even think about starting.
i ain't rite
Joined: Mar 2005
Posts: 65,561
Likes: 5,596
From: Marlboro Mental Hospital.
as a basic time-set, i use anything over 40 degrees 10 seconds, anything under 40 degrees 15 seconds.
my 88 will glow time for up to 20 seconds when really cold, like in 10 below.
my 88 will glow time for up to 20 seconds when really cold, like in 10 below.
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