I have and '82 chevy 6.2L Diesel (it's an '82 chasis with an '84 25' Regal body on top). Glow plug light will not come on & engine does not start. Battery is fully charged. I'm not sure if I am hearing the relay click or the fuel solenoids click when the ignition key is turned to the "on" position. The fault tree starts with a 20 amp fuse.

Prior to this problem, I had low voltage output from the alternator due to a loose belt.

1. Asuming that this is the same fuse as the 20 amp ignition fuse as in a gas engine, does anyone know where to locate the fuse? I did not see it in fuse panel under the dash.

2. Skipping to the end of the circuit, could the glow plug dash light fail to light if the glow plugs are bad? Do all need to be bad? (that's what I have assumed)

3. Does anyone know an easy way to check glow plugs? The method in the Chevy manual is quite involved. Since these are basically a heater, can I just check for continuity?

Any help is appreciated. I had to cancel our first outing of the year.

Mike,

I can't help with the other questions, but to check each glow plug you need to remove each wire (bar) and check for continuity for each plug. Any continuity means the plug is good.

You should be able to start it with only 5 or 6 glow plugs working. I used to have a 6.2 in a GMC PU, and I had two glow plugs out when I checked. It started easy enough, but even better when I replaced the bad two.

If I recall correctly, my dash light continued to work even with only 6 glow plugs active.

Tom

Well, after some digging and probing with the ol' trusty VOMeter, I found a combination of problems. The glow plug relay was bad (I still have not found the 20 amp fuse), all of the glow plugs were replaced and a couple of crimp connections that had worked loose. The GM fault tree helped with the analysis. I can only guess that something with a crimped connection started the whole thing. Electrical problems are always fun!

Hello, Mike... The HAYNES Diesel manual for these has a great diagnostic tree... I have owned 6.2's... the early ones like yours had a bi-metal glow-plug switch, housed in that little screw-in grey cylinder with the wires sticking out of it on the rear of your block. There is a bizarre and rare event that happens with this set up, causing much head scratching. You can start and run the engine for a few minutes, is starts to warm up. Not enough to start on it's own if you were to turn it off and on again, but enough to trick that bi-metal unit into thinking the engine was hot enough to start without glow-plug assist! So, the glow plugs don't fire, you can't go anywhere 'till the unit cools enough to allow the bi-metal switch within that "grey-can" to close...

Thanks� I�ll look for the HAYNES Diesel manual. Will it be a manual just on the Chevy diesel or is it a manual on something else in addition to the diesel? I did not see anything about this condition in the Chevy shop manual. I�ll have to look again. Is there any way to actually check the bi-metal glow-plug switch? Is this condition a sign of age or wear out?

Hi, Mike... the Haynes manual is one that says "DIESEL repair manual: GM and FORD vehicles", or something like that. I bought mine at Pep Boys... any place that has a good set of Haynes shop manuals has it, or can order it.

and the condition is just a design flaw. New glow-plug sensor things (the bi-metal tube) do it too. They re-designed it around 85', replacing it with an electronic set up. you can also wire in a by-pass switch that will kill the glow plug circuit when the engine is warm, reducing glow-plug wear. That's in the Haynes book, too. When I get home I'll get the Haynes book # and post it.

The easiest way to check your glow plugs is to disconnect each wire at the glow plug. Hook your test light ground clip to the + (positive) post of the battery and touch each terminal at the glow plug. The ones that light up are good. If you can jump out the solenoid (6 seconds max!) and the unit starts then its sounds like what Duteman is saying. After you get the motor running is the best time to check the glowplugs with the test lite method. Sometimes a hot motor will show up a bad glowplug or two. I know you said that you replaced the glowplug but I posted this reply for others with the same questions.

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Thank you for the follow up and for the detailed information. I�ll be looking for the manual that you suggested.

I suspect that the glow plug and relay problem extends back to the loose ground wire at the starter (covered under another post). When I removed the starter wire and nut, I found that there had been some arcing at this location. The nut had spots of metal all over it from the points of intermittent contact. I replaced the nut when I fixed the problem and cleaned the contact. I theorize that the arcing may have caused the problem that took out the relay. I suspect that the arcing resulted in a really high voltage and took out the relay or the crimped connection before the relay (which was replaced too).

Can I check a glow plug that been removed from the block?

Mike... just check visually, and for continuity. If it's not melted at all and you get continuity it's gonna glow when power put to it. Careful, though, I think your system has 6V. glow plugs, so don't test it by trying to put 12V on it to "see if it warms up", because it will indeed! This 6.2 system is really pretty reliable, usually any problems are relay or switch related. did you get that HAYNES book? I still have to find mine at home and I'll send you the HAYNES part number.

Mike, the HAYNES "TECHBOOK" number is 10330...

Thanks for the part number. I'll look at my trusty garage!