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Discussion Starter #1
I measured resistance at the gp's on my 95 PS 7.3l, and this is what I got:

ps front to back 1.4, 2.5, 1.8, 1.3 ds front to back 2.1, 1.4, 1.8, 1.8

I read an account that said anything over 2 ohms should be replaced, and another that said a good one reads .8 to 1.2. j

I'm figuring they're weak, and that that's why I get white smoke on startup in the winter.. but less so if I let it sit longer before starting. Just wanted to ask someone more experienced than I am whether or not they should be replaced.

Thanks.
 

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I'd say all your glow plugs are good. Differences in your resistance readings are likely due to connector conductivity or how you hold the ohmmeter probes onto the contact points. From my experience I either get resistances like yours or infinity (i.e. open circuit).

Hopefully you are measuring resistances on the valve cover connectors. That way you don't have to remove the valve covers. You measure glow plug resistance between the front pin and ground for one plug and the rear pin and ground for the other plug.

Are you using your block heater? Here's what I do in winter for easier startups:
1. Start plugging in the block heater when outside temp drops below 32F. It will start up at 32F, but it will start easier if the block heater is plugged in for 1 hour or so before you want to go.
2. If it's 10 - 15F or high wind, you may need longer.
3. A word of caution: After the block heater has been on for 30 min or so, go feel the connector plug to see if it's warm. If it is, unplug it and clean the spade contacts with scotchbrite. Spray some contact cleaner in the female plug. Plug it in again and check the temp. It should be cooler. A friend of mine was leaving his plugged in all night in his garage. Excess connector heat burned up his truck and almost burned down his house.

If you're still having problems, check the glow plug relay to be sure you're getting power to the glow plugs during startup.
 

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Discussion Starter #3
Thanks.
I was cking them because my gp relay had seized at the top and burned up the relay outer case around the battery side contact terminal, after which I tried to short the two post wires to energize the glow plugs, but it wasn't starting, so I thought the relay had seized at the top and burned up my glow plugs.
Problem was that I wasn't energizing them long enough. I have a 94 idi 7.3l, and on that truck, you energize the gp's for about 15 seconds max at a time. I assumed it was the same for the 95 powerstroke, but I was way off. It was coughing but not starting because I was energizing them for 15 seconds.. then breaking the contact and trying to start the truck.
I replaced the relay w/ a MR-99 from autozone ($18.99) and it started better than it had before, so the relay had probably not been well for a time. I'll know now that the gp's in the ps are way different than those in the 94 navistar, at least with respect to how long they can be energized w/o damaging them.
 

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My factory manual says 0.6 to 2 ohms is a good plug.
 
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