No code on bad glow plug strange & weird

warp2diesel · **Posted:** Mon Jan 10, 2011 10:20 pm

I had the symptoms of a bad glow plug, rough start, with no codes being generated.
I checked the glow plugs with a VOM and one of them #3 acted like a capacitor when tested for the resistance.
Like a capacitor the resistance reading would show on the display for an instant and then indicate an open circuit.
I replaced all 4 glow plugs with new Bosch spares and treated them, very very carefully. Two spun out with my fingers and the other two I screwed them in and out with WD-40 on the threads until I could spin them out by hand. Since I heard that one of the causes of breakage is caused by doing the job with a cold engine. I plugged in my block heater for 4 hours, drove a little until the engine was half warmed up, plugged the block heater back in to keep the head warm. Made it better for my hands working outside in the mid 20s (F).

When I got the new ones in, I checked the resistance and all four checked out, then I reassembled.

After I was done, I retested the bad #3 glow plug and it still acted like a capacitor.

I would bet that some (not all) of the broken glow plugs are due to some Techs using air ratchets or other impact tools to get them out when stuck. Some Techs use air ratchets to remove Spark Plugs :banghead:

, why not on glow plugs :banghead:

. Not on my engine.

This morning,a normal start, no more shake for the first few seconds.

BlackLibertyCRD · **Posted:** Tue Jan 11, 2011 1:07 am

did you put the old or new metal glow plugs in?

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

Warp,
Earlier this year, I had same issue. I had had winter weather starts but no CELs. Resistance of glow plugs was on upper end of allowed range. I believe they were around 1.1 ohms. No MIL light. I replaced all 4 and was back to normal until last month when no. 3 failed with a MIL code. So far no problem starting and it'll be -10 deg F tonite. Vehicle is outside because wife's GC CRD crapped an alternator. As long as it doesn't gel, it'll start.

warp2diesel · **Posted:** Tue Jan 11, 2011 7:31 am

BlackLibertyCRD wrote:

did you put the old or new metal glow plugs in?

I used the old ones, Chrysler's switch over looks the same as what VW went through with their switch from Ceramic glow plugs to Steel Wrapped Ceramic. It took VW a couple years to figure it all out and I don't want to be one of Chrysler's Beta Testers on my dime. When VW got it all worked out, the last generation of steel wrapped ceramic glow plugs worked as a direct replacement with no need for a new Glow Plug Controller and/or flash.
One thing that bugs me about the, "UPGRADE" is using a Glow Plug Controller with the same Bosch part number as mine and telling everyone it is a new Glow Plug Controller. It all sounds like Chrysler is dancing with the EPA Acid Head Hippies and waiting for them to get tired and go home, I hope it is not slow dancing. :ROTFL:

Two years from now the dance should be over.

MrMopar64 · **Posted:** Tue Jan 11, 2011 8:25 am

One thing to keep in mind - the metallic glow plugs (no such technology as metallic-wrapped ceramic) have already been in production with the 07 model year KJ in Europe with much success. It's not a new technology or experience...

ATXKJ · **Posted:** Tue Jan 11, 2011 1:33 pm

as to warp's capacitor - on your measurement - did you directly contact the end of the plug? - or measure through the wiring harness?
if it's through the harness - the conductor may have 'micro' cracking or internal damage that gives a capacitive effect.

warp2diesel · **Posted:** Tue Jan 11, 2011 11:09 pm

ATXKJ wrote:

as to warp's capacitor - on your measurement - did you directly contact the end of the plug? - or measure through the wiring harness?
if it's through the harness - the conductor may have 'micro' cracking or internal damage that gives a capacitive effect.

Through the Harness at the GCU, At the plug between the main harness and harness going to the glow plugs, on the glow plug screwed into the head, and in the house next to my computer glow plug in my hand. Same in every location, same results, #3 acts like a capacitor.

ATXKJ · **Posted:** Wed Jan 12, 2011 12:02 pm

warp2diesel wrote:

and in the house next to my computer glow plug in my hand. Same in every location, same results, #3 acts like a capacitor.

That kinda eliminates everything except manufacturing defects in the plug......

warp2diesel · **Posted:** Wed Jan 12, 2011 11:03 pm

ATXKJ wrote:

warp2diesel wrote:

and in the house next to my computer glow plug in my hand. Same in every location, same results, #3 acts like a capacitor.

That kinda eliminates everything except manufacturing defects in the plug......

Original glow plug with 69.2K
It went bad this way on its' own.

WEIRD

No code on bad glow plug strange & weird

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