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Glow Plug Troubleshooting

O

oilyfuel

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I think my glow plugs are not glowing.

Unless I plug in the block heater all night and day making the engine about 110 degrees, I can't get the engine started. If I get it started and drive, it's hard to start after sitting a while.

The glow plug light comes on.
There's a click.
It doesn't matter if I use my manual switch, there's still a click and the light comes on.
All the wires to the plugs (except that rear right one which is hard to reach so I didn't bother) measure 3.5 ohms to ground (negative terminal of battery).
The plugs have infinite resistance to ground.
I pulled one out and there's no continuity between the tab and the tip (infinite resistance).

I noticed between a wire and its plug, there was 0.03 volts when using the manual switch and 0.11 when turned on by the relay/controller.

The batteries drained almost a volt within a week or two of sitting (no driving).

I charged them in the truck overnight/day and they held enough charge to start the engine.

Maybe I need new batteries since they're about ten years old (Optima red top, drained a few times).

Maybe all the glow plugs are burnt inside (Wellmans, I believe they wouldn't do that).

Maybe there's a short from the wires to ground?

Batteries, plugs, short... does anyone have any ideas?

Thanks

1985 K10 6.2 Silverado
 
Infinite resistance on the glow plugs would tell me they are toast. Any good glowplug i've seen is ~0.8 to 1.0 ohms.

Wellmans have a mixed history. They used to be awful. THey'd swell and burn out with normal usage(nothing over factory GP time) in less than a year. Some swear by them, i wouldnt' use them if they were given to me. I only run the Bosch Duraterm #80034, in both my trucks.
 
Pull out a glowplug or two from the driver's side, test them using 12v and a set of jumper cables... they should glow cherry .

I bet not... sounds like you need new glows. Wellmans are famous for that.
 
Wellmans=Crap. Pray they come out. If your using an override to boot I'd guarantee they are toasted. Rockauto has the best deal on Duratherms. I personally so no difference between them and 60gs.
 
I foolishly on a hasty time schedule changed to wellman thinking they would help a year or two ago. If I'm lucky, I still have the old ones which I think were probably 60G. I had to put those in when I discovered one broken off in the rear left cylinder. I think that's the one that leaks too, but maybe from not replacing the injector gasket when I tried to fish around for the broken tip. I'm sure it probably got past the valve or embedded into the piston head as I've heard happens. I guess leaving the glows on over 25 seconds probably did these in finally. First thing will be to search for the old ones and see if they still work. Then see if the newer ones still work. fun.
 
JiFaire said:
Pull out a glowplug or two from the driver's side, test them using 12v and a set of jumper cables... they should glow cherry .

I bet not... sounds like you need new glows. Wellmans are famous for that.
Click to expand...

You need to ground the threads as well as giving the terminal 12v.
 
s-mack said:
You need to ground the threads as well as giving the terminal 12v.
Click to expand...

Sorry - figured he knew that... clamp the negative jumper cable on the collar, touch positive on the spade.

While we're at the PSAs, don't touch the end.. they get some kinda hot if they're working!
 
A special tool for swollen plugs? Is that like a prechamber cleaner that goes in the plug port and scrapes out carbon except that it obliterates the plug? I know there are plug reamers for mercedes to do that (not the plug obliteration, that's an exaggeration).

Anyway, I'm assuming the tab is insulated from the rest of the outer covering (tip, threads, collar, casing). I tried a test but didn't get the plug hot so I'm not sure if it was the contraption I used (not jumper cable, ignition advance switch) or a bad plug. Hopefully will get to it today. Thanks for the PSAs. I'm sure despite them I'll find a way to burn myself at least once out of 8 tries, partially if I'm lucky. I found my old plugs though which is good. I'll probably test all of them first. One I pulled from a box (Wellman's WAP box I put the old ones in) has this info on the plug which I'm assuming is AC 60G (remember them being cheapest back in 2002something at NAPA for $10.09) :

AC DELCO
0 100 271 107
046
10.5v

Since acdelco.com didn't wanna give up their secret codes, I googled and found several posts claiming 0 100 271 107 is for 60G. Now just have to test them all.
 
I'm hoping I don't have to use that tool, but at least I know it's an option. Sounds better than knuckle-busting with vise grips and no space.

All my old AC Delco 60Gs are still measuring between 0.8 and 1.0 ohms. I guess that one Wellman I pulled must actually be bad with no continuity. I wouldn't be surprised if they all were that way after my most recent extended glows trying to start in the cold and subsequent hard starting.
 
Even though the are reading good per resistance, only way to know for sure is to energize them and see how fast/complete they glow tip to center should be @ full glow tip to center in 4 sec or less, glows are sort of like a electric stove element or water heater element that reads good with a meter but still does not fully warm up when energized.
 
I did do a glow check on all the Delcos before seeing your post. They all smoked, but as soon as I saw the tip glow red, I disconnected the electricity. All of them seemed the same though I didn't let them glow to the center (to save battery charge). Once I installed them, the truck started right up without plugging in the block heater at all (warm day). I tested the ohms (no continuity) and glow on the Wellmans and they were all absolutely dead. None were swollen, but then I bought them in 2005 and installed them in 2009. They lasted just over their warranty period of one year of use I guess. All that extra manual glowing in the teen temps probably burned them all out, every single one of them. After about four years of continuous use in Colorado, and sitting for four years afterward, the AC Delco 60Gs are still working (at least today). It's a good thing I saved them. I thought the Wellmans would be an improvement, but obviously not.

I guess the next best thing is an Espar diesel coolant heater for another winter in Wyoming. Even coasting down cold mountains in winter starts freezing my engine and pouring white smoke out the back. A heater would probably at least keep the coolant warm, then an improved heater blower motor, but that's for another topic.
 
60Gs will take manual glow much better than over the counter part stocks, top of the line but you pay for them are the Bosh duratherms. I got pretty good service from delphi glows, as far as hard starting how old are the injectors 100K is the general recommended service life for the 6.2/6.5 injector
 
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