Bench testing glow plugs

[markrinker]

Is there a simple and accurate method for bench testing glow plugs?

[catmandoo]

i bought a pop tester off ebay last year and just went thru putting inj's in my sub last sept,and all of them showed right at 300 psi low.think i gave like 150 for it but well worth every penny.

[catmandoo]

try this.ebay #4516584458 mines almost identical.

[Billman]

OK. I give up.

How do you 'POP' test a glow plug?


You've got Injectors on your mind...

[eracers999]

Mark:

Taking a digital volt ohm meter and setting the selector knob to the 200 ohm scale or just leaving it on auto if it is newer one the test is very simple.

Connect the red lead to the spade connector and the black lead to the ground or the outside case of the glow plug, look at the reading, anything under 1.5 ohms is good. A bad one wont read at all, one that is not getting very hot will read about 1.7 or higher. This test can easily be performed with the plugs still installed. Remember you must have a DIGITAL vom. This test will help you find a bad one in no time.

Kent

[markrinker]

Interesting, anyway. Catmandoo - if I sent you 8 injectors via USPS, what would you charge to test them for me?

Thanks, Kent for the glowplug test method. I think there are a few bad ones on #1.

[Subzilla]

Kent,
I just replaced my GP's in my new-to-me '86. Checking the old 9g's (yes, 9g's) 5 read 1.2ish, one had no reading, one read 5 ohms and one read 10 ohms. You said anything above 1.7 and they were getting hotter. Was this a bad thing? Is this a sign that they were on their way to burn-out? Just curious.

[eracers999]

Subzilla:

Read my reply very closly (above). It says that the ones not getting very hot will read 1.7 or higher. Thanks

Kent

[moondoggie]

Good Day!

I just hook them to my 10A 12V battery charger. They peg the meter. This makes sense, since they draw ≈ 15 or 20 amps @ 12V nominal. On edit: If the battery charger has manual & automatic modes, be sure to use the manual mode.

It's really hard to get accurate ohm readings when the resistance is as low as these glow plugs' resistance is. Simply scraping the meter's test lead across the glow plugs terminal or body can change observed resistance by several tenths, sometimes several ohms. Technique is very important.

I prefer to test things under as close to normal operating conditions as possible, hence the battery charger test. Plus, the battery charger test is simple, & most folks own one. ;)

Blessings!

Brian Johnson, #5044

[ 01-06-2005, 08:45 AM: Message edited by: moondoggie ]

[Subzilla]

Kent,
My bad. Still trying to get use to these new glasses! :cool: So I definitely had 3 bad GP's.

[markrinker]

I am going out to test my new set of 8 on the battery charger, Moondoggie. If I burn my fingers, that will be my second ER visit in as many days.

Yesterday, I got 8 stiches in my forehead from unhooking my snowplow. Didn't have the plow jack in place, pulled the last pin, and the plow dropped suddenly to the ground. Plow light hit me square in the back while kneeling, facing the truck, and launched me head-first into the bumper... (Okay you can stop laughing now!!!)

[catmandoo]

man my luck the blade would have landed on my foot and the light would have cracked me in the head,at the same time.mark,send me an email at kjmoore66@hotmail.com

[moondoggie]

Good Day!

Ouch!!!!! Unfortunately, I'm in no position to laugh at someone else in a situation like this - been there tooooooo many times myself.

When I've bench-tested glow plugs, I clamped the hex in the bench vise - no problems.

Blessings!

Brian Johnson, #5044

[More Power]

Many diesel techs just use a 12V test light to test the glow plugs. Connect one lead from the test light to the battery positive terminal, and then touch the other test light lead to each individual glow plug. This works well to catch a completely dead plug, but may not show one that is below par.

I prefer to test each glow plug using a multimeter on the 20A setting. Connect one lead to the battery positive and then touch the other multimeter lead to each individual glow plug spade terminal (after unplugging all of them).

An AC-11G or AC-60G will initially read about 16-amps then drop to below 10-amps in a couple of seconds. This is the PTC self-regulation at work. If the plug is pulling a nominal initial amount of current and PTC's down to a level similar to the others, it's OK. A test for about 5 seconds is enough.

Don't test an AC-9G (or equivalent) using this method. These non-PTC plugs will burn out in about 15 seconds.

Glow plugs 4 & 6 on the turbo side are the hardest to test. What I do is unplug all glow plugs except 4 & 6, then touch the multimeter lead to the GP side of the GP relay. It should pull over 30-amps initally. If you're only seeing 16 that tapers down to 10, you've got one bad plug.

MP

[moondoggie]

Good Day!

Wow - I completely forgot the test light method.

The 20 amp meter method is clearly the best test. As usual, it's pretty hard to beat More Power for troubleshooting ideas. :D Actually, the only reason I didn't record this idea myself is that all my DVM's have only had 10 amp capability. I (probably foolishly :( ) assumed that most folks also wouldn't have an amnmeter capable of this task. That's why I wrote up using a battery charger. The ammeters on these are of poor accuracy, but at least all eight glow plugs should show the same test result when tested this way.

Blessings!

Brian Johnson, #5044

[DennisG01]

OK, I have a few (possibly) stupid questions! tongue.gif

Moondoggie - when you use your battery charger, do you just touch the two charger leads to the spade and "hex" part of the glow plug and then turn on the charger? Could it be done with the plug still in the engine?

MP - I don't have a 20 amp multimeter (so I am not speaking from experience), but I was just wondering that if the plugs initially pull 30 amps, how come it doesn't blow the fuse on your meter?

Anyone - what would be bad about using a portable battery pack to test plugs; just hook up the two leads and watch the plug get hot.

[CareyWeber]

Originally posted by catmandoo:
i bought a pop tester off ebay last year and just went thru putting inj's in my sub last sept,and all of them showed right at 300 psi low.think i gave like 150 for it but well worth every penny. catmandoo,

Please email me at carey dot weber at us dot army dot mil (no spaces). I'd like to ask you about using how you use your tester. I bought one too.

Carey

[Kennedy]

I do the simple test light method to detect open ckt...

[moondoggie]

Good Day!

[i]

[DennisG01]

Thank you John and Brian. That clears things up for me! :D