I was experiencing progressively worse cold starting, requiring more & more cranking -- in moderate temps, this being Florida. I searched the files .... checked the plugs for resistance -- all about .8. Checked the relay -- working. Checked whether there was power to the plugs -- all had 11.5 or 11.8 volts. Still the starting was bad -- thought I wouldn't get it started once or twice ..... and hard on the batt & starter ..... so I replaced the plugs (in stock & about $46 at Autozone). The car immediately started fine. Are the plugs just coated with something that I can clean off & keep them for spares, or are they trash?

Probably just ebay material now. Really for curiositys sake since you have them out why not test them across battery to see if they really still go red hot and stay red hot for a full minute or not before throwing them. Developing suspicion that the aging charactaristic may be the natural increase in resistance under load no longer is there but has been replaced with a much more rapid and larger increase of resistance under load. Watch you do not burn yourself in the process. This type of situation means that a test in car using current draw instead of resistance check may be a far better standard of approach to glow plug testing. May eliminate the quandry of they check good resistance wise but car does not start should I change them anyways on spec. Just have to wonder if individual current draw is a more conclusive indicator than just a resistance check. I really think it might be as current is going to drop as element heats due to increasing resistance and the time factor plus the low point in current draw may be a far truer and revealling test.. Supose some of these questions should really be directed to the plug manufacturers as the problem seems steadily to come up on mercedesshop to stimulate my curiosity. At the least one would think the manufactures could suggest a much better way to really test the glow plugs while installed in engine.

Autozone doesn't have Glow Plugs for my car. Kragen has Bocsh with One Year warranty, but $22 each . Bemmerparts.com has Beru for $15 each. Does anyone know where I can get these glow plugs online with warranty ? Thanks.

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1992 300SD, 290K miles.

I just bought mine for $11.50 each at ***************.
Free shipping over $50. No tax if you don't live in AZ.
No idea about warranty....doesn't matter...
They are Bosch plugs

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

All parts are covered by a one-year warranty, unless otherwise specified, subject to the return and warranty terms outlined in our Terms and Conditions

============

Thanks JJ. I found this from their site.

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1992 300SD, 290K miles.

Ya, check out their prices...
I have bought from them:
IP Shutoff Valve, oil, fuel, and air filters, GPs, valve cover gasket, lubro moly diesel purge, primer pump, all sorts of vacuum thingees, line, hose....
They consistantly have the cheapest prices I can find anywhere. They sell quality stuff, and they ship fast.

No, I don't work for them
Just love good deals and service.

p.s. sometimes parts are hard to find there, or don't come up. search different ways.. you will probably find it. That diesel purge was a pain in the rump to find. I finally got it with the manufactures part #.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

Thanks for the feed back. I saved the plugs and will test them as suggested, direct to the batt. I'll try to see what load they draw, at the same time, tho I only have a cheap ammeter.....

This will have to wait for next weekend, tho as I spent today changing oiil in the tranny (Mobil 1 10-30) and diff (NAPA 30/85/90), managing to get oil all over myself & the driveway in the process. Next time I'll get some kind of container/pump. I had a thingy I'd used for some yrs which is a valve & hose that screws onto a gear oil bottle ---- and always leaks, is hard to keep in the hole, etc, etc. This time the top popped off the bottle & Mobil 1 poured on the driveway @ $5/qt. AAArrrggggghhhh.

Got my GP's at BenzBin
http://www.thebenzbin.com/
Parts Ordered
Mercedes Benz 1983
Monark Glow Plug Price: $7.68
Qty: 5
Part #: F1100-11683
Sub Total: $38.40
Shipping: $5.50
Tax: $0.00
Core: $0.00
Total: $43.90

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Doug
'83 300SD "Old Gold" 170,000 mi.
'82 380SL "Green Machine" 190,000 mi.

Some days you're the pigeon, some days you're the statue... I'd rather be the pigeon!

That sure is cheap...
anyone have long term experience with Monark stuff?

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

I had a guy tell me the other day that glow plugs are like cigarettes, after a while the ends burn away and they don't work as well as they did when they were new - they'll pass a resistence test though...

Don't know if that's true or not, but resistance is fine on my plugs as is the relay but doesn't start well when cold, works fine when the weather is warm. So, I'll probably change them out one of these days.

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-livin' in the terminally flippant zone