Recently my 84 300SD was getting harder and harder to start. I following the complete test for glow plugs and everything checked out fine. Glow plug light on, fuse good, 11V to each glow plug, and each glow plug tested at 1 ohm when cold.

I thought, what the heck is going wrong? I decided to pull the glow plugs and check them individually on the bench with 12V. Apparently, glow plugs will show 1 ohm but not glow at all. Two of them glowed red hot immediately. So I replaced them (actually not too hard, did it in 1 hour without taking off the inj. lines) and solved the problem. Lesson learned: if a diesel starts hard, there's a problem somewhere, you just have to find it! (profound, isn't it?)

I'll probably get a lot of flack from the diehard Bosch guys, but I used Champion glow plugs that are advertised as a "longer, hotter" plug for better starts. Yes, I know, be wary of those claims, but how will you ever know until you try it?!? So far so good!

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84 300SD running on WVO

I'm glad you have a good system for replacing them because you will be replacing your Champions in the not too distant future.
Betcha go back to Bosch after that......

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

I've experienced the same issues with testing GPs. Pulling them out and giving them 12v is the best way to test them.

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Champion Glow Plugs have worked well in my Volvo Diesel. Since 1992 I have replace I believe 3 of them. When I remember I use the Glow Plugs every time. But out here in Southern CA the Glow Plugs will not get as stressed as they would in colder states.

Without removing the Glow Plugs they could have also been tested with an inductive Amp Meter or with a regular Automotive Amp Meter with at least 60 amps on the gauge could have been wired in series one at a time on each Plug.

When I tested a good Plug with a regular Automotive Amp Meter it pegged the gauge to 60 amps hung there a second or so and as the plug got red the needle went down to around 16 amps and stayed there.

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84 300D, 82 Volvo 244Gl Diesel

My 190d acted up (glow plug light on for short time for cold start). Replace Beru glow plugs with Bosch and normal light sequence restored. Also noticed my volt guage low for 15-20 seconds after cold start with Bosch plugs. Further invetigation showed test ligh on at glow plugs after cold start for 15-20 seconds. That lasted a couple weeks, now the voltage is 13.9v after start and no test light at glow plugs after start. It starts and runs good and I figure it must be the glow plug relay faulty?

I use put in whatever they had at store until i had 3 go out in my vw within 3 months i stick with beru or bosch exclusively cause i would spend 3$ more per plug to not do that job 2 or 3 times a year!

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2004 Infiniti G35 3.5L 6mt Coupe 73K miles 25.6mpg ytd
2001 Green Audi TT 225 AWD Roadster 71K 6sp 30.9mpg >>STOLEN<<
1982 300D Turbo 231K 120hp? 28.1mpg YTD

I know it goes against the popular choice. I bought the car used in 1992 and have only been on the Internet for about 2 years. What was available locally at a resonable price were Champion Glow Plugs.
I do not think a failure of 3 plugs in all of this time is a bad rep.
ALso they are not the same Plugs as the ones for Mercedes and are slightly shorter.
If anything goes wrong with enough of them I have a spare set of NKG Glow Plugs from Ebay that I will try.
Also as I said it is not cold here.

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84 300D, 82 Volvo 244Gl Diesel

You should barely need glowplugs at all in SoCal, especially last week. I stayed in Long Beach Wednesday night (Holiday Grim) it was 92F when I checked in. 50F when I got home.

Anyway I'm given to understand that most reasonably priced multimeters aren't sensitive enough to detect failed glowplugs as the actual resistance is well under 1ohm.
Having replaced glowplugs (twice now) at 20F in the dark with my wife holding a flashlight I'm big on replacing them well before actual failure (like yesterday at ~65F). Some people rail that you only need to replace the one or two that fail but they last a long time so I figure having all new ones every couple years is good insurance. They do get a workout here in New England...

-Curt

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Sadly Benz-less

DonDS,

Are U sure your meter wasn't displaying a "1" for an open circuit? Some meters do this.

All the GP shouldn't read exactly the same. Did U pull the GP cable connector out of the GP relay when U measured the resistance of each GP? If U don't remove the GP cable, U are reading parallel resistance and will get incorrect readings.

The best placed to measure the GP resistance is plug the test wire into the holes in the GP cable connector. A bananna plug works well. Testing this way will also show any resistance in the GP cable wires or the connection to the GP.

Try measuring the resistance of each GP when it is out of the engine and see what resistance U get.

P E H

I was reading the meter correctly for resistance, and it was 1 ohm, however I did not pull the GP connector. I didn't realize this would make a difference testing R of each glow plug, so I stand corrected! I guess I'll be sure to do this when my Champion plugs fail prematurely!

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84 300SD running on WVO

Don DS,

See my update.

P E H

I tested the old glow plugs for R and 2 were open and the third was 0.8 ohms. As I recall all 3 didn't glow red with 12V applied, but I may have done that incorrectly on the one with .8 ohms R. I may try the 12V test again to see. Nonetheless, my initial test for R should have been done with the GP connector pulled. Thanks PEH for the correction. At least it's back to easy starting now that cold weather is coming. This am there was frost on the ground! That's a S. Ontario fall for you!

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84 300SD running on WVO

Don DS,

Keep the bosch GP that reads 0.8 ohms. U might need it to replace one of the new Chamipon GP soon. BTW, where did U get the Champion GP? I have never seen any.

I never liked champion spark plugs, had lots of trouble with them when I used to drive gasoline powered cars. I don't like their GP either. I have found that Bosch GP are superior for long life.

P E H

Did you ream the glow plug holes ?!?!?!

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Sharing my partner's 2012 Forte 5dr SX til I find my next 123 or 126..
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Do I miss being a service advisor ???

And apply anti-seize compound?

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1980 300 TD

1997 Dodge Pickup/Cummins 5.9 12-valve