I've heard there's a difference in durability between the old style coil glowplugs and the later quick-heating pencil type plugs on Mercedes diesels. I just changed the 6 glowplugs on a friend's 1986 524TD BMW. (Yeah, I know it's not a Benz but I hoped some of the diehard Diesel fans here would have an answer. I don't think there's any good BMW Diesel sites.) 5 of the 'old' glowplugs were bad. Thing is, I changed them about 3 years ago. They're the 'quick-heating' pencil type plugs. Is it normal for these to fail after 3 years?

Thanks All, Mark

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DrDKW

Hello Mark DiSilvestro
To answer you.
The glow plug life is variable.
How many times do you glow on cold days?
The relay controler can be bad, glowing too long.
The glow plugs may have been substandard.

I would replace the relay and glow plugs, if the car where mine.

Have a great day.

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ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
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1985 300SD
1983 300D
2003 Volvo V70

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Which raises the question; don't the glow plugs turn off as soon as the engine starts running?

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Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback

On the BMW there's an orange 'glow-light' on the dash when the key is switched on. When that goes out, a green 'start-light' comes on to tell you to crank the starter.
I'm sure glad I didn't have a problem like the poor guy that snapped off an easy-out inside his glowplug!

Happy Motoring, Mark

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DrDKW

The plugs in my 300D have not been changed since the second owner bought it with 120K miles on it, now has 246K. Still starts alright.. Go figure..

It's almost a yearly thing in the VW's, replacing the plugs, and not using cheap ones either. Who knows.

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One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K

Just got a new set of GP's from Kragen(Autolite) after pulling my old ones which were pencil-type. Tried testing each one individually on the pos terminal, not one got even warm... Then tried same on different car that has brand new battery, same thing...
Then tried the new ones to see if they would glow ----NOTHING!!!! Not even warm.
Any help/suggestion? I don't want to put in the new ones unless I can get them to glow hot. Same thing when I tried holding the plug with jumper cable
grounded to frame or block---not even warm ?????What the F****!!??
I'm starting to stress hard....:

to my knowledge the ones in my 240D have NEVER been changed

It is really illogical to have that many bad plugs. All the new ones and all the old ones. You are completing the circuit by grounding out the lower part of the plug? Not just putting the threaded tip of the glow plugs to the battery positive terminal? The current must flow through the plug to ground. Another quick check is with a ohmmeter for continuity.
The only other sensible problem might be very dirty connections or a defective jumper cable on your test set up.
Watch you do not burn your fingers when those glow plugs come to life. They get really hot.
Post again if you cannot get a working test. Autolite are not the best plugs for these cars. If you can return them for a german brand it might be worth the effort down the road.
Also if every glow plug in your engine was burnt out. You would not just want to put a new set of glow plugs in before checking the relay for a very long cycle problem.
A quick test of your test setup. Clamp the jumper cable on the negative battery terminal . Brush the other end against the positive terminal. If it sparks it proves continuity of the jumper cable and the negative connection at the battery post is good. You should then be able to test your plugs.

Mark- Whunter hit the nail on the head. I fixed a VW that had the GP timer stay on a the GP blew apart. The piece was big enough to damage the valve, piston and head in that hole.

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83 300SD 305k, A work in progress
81 VW 1.6L Rabbit P/U, No spark required

This may sound like a dumb question, but are you grounding the body of the glowplugs you test to the negative terminal or are you only touching the GP to the positive post?

What I have been wondering from time to tie over the years is if the GP go bad will they eventually damage the relay or vice versa. Anyone know? How about it Whunter, will one cause the the failure of the other? They all fail about the same time or is it more a cascade effect as seen in electronic circuit boards?

One thing about no glow plug(s) is all the smoke that comes out the tail pipe for half a minute or so, enough to maybe have one of your neighbors call the fire dept on you.

Another thing I have often wondered is how these cars run 200k or maybe twice that w/o ever replacing or rebuilding the injectors? Then when they are replaced or rebuilt they are seldom ever pop tested. It would seem to me that it is not that big a deal to pop test and shim the injectors when or if they are rebuilt after two or three hundred thousand miles. Even those that rebuild and replace the nozzles seldom if ever replace the springs in the injectors or for that matter have the injectors pop tested unless they just are not reporting that part of the repair.

I hope I haven't stirred up a hornets nest here or sounded like a complete idiot.

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'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.

Use Bosch or Beru GP's. Look at them as a maintenance item, like sparkers on a gasser. I have heard to replace them every 1-2 years or even longer if so inclined. I do follow if one is out, replace them all. Even in warm weather, the GP's are energized.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Man on some models like our '91 that is real labor intence and may require removal of intake.

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'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.

True. Let me preface by saying "on the OM616 or 617..."

But, if you are working on the '91, and have to remove the intake for one plug, still may as well replace them all.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Well that would be a given as for as replacing all the GP's in our car, but that's not really what I am getting at here.

What I am wondering is about normal life span. Remember everyone driving a diesel does not necessarily have skills/tools or ability to replace glow plugs on their car. Who would want to go to all the expence of every two years having to replace GP's and be out all that money. GP's are not like replacing sparkplugs in a gasser either, they cost a lot more and spark plugs in average gasser for the last 20 years generally last min of abut 50,000 miles if not more.

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'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.