1983 300D won't start-- glow plug? Battery?

My 1983 300D Mercedes started having problems a week ago. When I turned the key to start the car after the glow plug light goes out, the engine turns over but didn't catch. The first time this happend it took about
15 tries to get the car started. The next time, about 25. Then about 50. And the last time around 75-- eventually needing to jump start the car because the battery wore down in the process. This problem only occurs the first start of the day-- once its warmed up, it starts up with no problem. However, now the car is not starting at all, and instead of the once powerful attempts by the car to start up, its now weak and isn't even close to promising.
-I have tried letting the glowplugs warm up repeatedly, but it didn't seem to help. -I have tried pushing the gas a bit while turning the key and this seems to have no impact at all. -The car was releasing exhaust when the engine was struggling to start. -I have a new alternator -5 months ago or so my battery was tested and was in good condition
What do you think the problem is?? Combustion? Glow plugs? Help!!
Thanks, Kate
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Kate,
How old is the battery? Even though it tested "good" five months ago it may not be holding a charge over night anymore.
Josh
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Any battery that can start a car in 15, then 25 then 50 tries is good!
It won't be for much longer if you keep doing this. It takes a lot off a batteries life to discharge completley. A LOT.
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Richard Sexton | Mercedes stuff: http://mbz.org
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Kate,
The glow plug system has an 80 amp fuse, a/k/a fusible link, that's under a plastic cover on the glow plug relay - located on the left fender. The cover slides UP. Pull the cover UP and check the link - it's probably broken or melted. If so, that's THE PROBLEM!
These links are sold by the dealer and on-line for about $2 each, one is needed, also buy a spare.
This should solve it, if not, come back.
Tom
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Might be, BUT, th eway it failed - getting long and longer to start sounds like it had two working glow plugs, then one then none. A fusable link busing would behave the same way each time, it wouldn't get progressibly worse.
At any rate, check that first, who knows? Buy two spares and put them in the glove box anyway. It'll fail one day.
Sadly there's no way of testing the glow plugs while they're in the car.
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I had a similar event happen about eighteen months ago. I have a 1983 240D. A new battery took care of everything eventhough the testing of the old battery showed it not to be "down".
Helen
snipped-for-privacy@gmail.com wrote:

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Had the same problem on my '81 300D. Although I burn biodiesel it had always started up great. When the problem began I changed the glow plugs since the fuse link was fine and I was getting current to the then installed glow plugs. I made the mistake of putting in Autolite glow plugs instead of Bosch. It started fine in the early morning if I gave it a slight shot of starter fluid in the air filter intake tube at the front near the radiator core support, not enough to cause any diesel knocking. Later in the day it started okay but without near the gusto it had in the past. I finally solved the problem by installing one of those new glow plug relays which keep the current flowing for about three minutes. The kit I bought also included new Bosch glow plugs. It now starts up on cold mornings in less than 5 seconds of cranking. I'll never use anything but Bosch plugs now. Incidentally, my 240D (also on biodiesel) starts without a bit of hesitation, regardless of the weather.
By the way, I've been using well-filtered WVO blended with small amounts of kerosene, gasoline, and a couple of other additives which I purchase locally. Works perfect despite rumblings from all the naysayers. I've heard some who complained about the "gunk" left in the bottom of containers when using the "recommended" method of purifying WVO and claim they would never put that through their engine. However, they fail to realize that Dr. Diesel designed his engine to run on vegetable oil and you get exactly the same "gunk" when processing virgin peanut, canola and other types of oil. Just thought I'd throw that into the mix. Incidentally, at about 80 cents a gallon I laugh at the price of diesel as I drive past service stations these days.
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Kate; You have no glow plugs left. Put in new ones and all will be well.
I had this problenm this winter when it was very very cold. I would start the car and let it run till the water came up to temperatire every 6 hours because it was SUCH an ordeal to start when very cold and no glow plugs. I had to use two batteries and a 50 AMP battery charger/boost.
You can change the glow plugs yourself VERY easily. Get a 19mm wrench and take off the injector rails. Those are the snakey steel lines going from the injector pump to the injectors. Looks scary and OMG you're taking your engine apart but it's really really easy. Undo the bolts at the injector pump. Undo the bols at the injectors, it now comes off as an assembly all at once, place it upside down on the air cleaner, cover with a cloth.
Now you can yank the glow plugs. It's a 13mm socket IIRC and is as easy as changing spark plugs. Take them out, put in new news, tighten them up to about as tigh as they were by feel.
Some poeple try to do this without removing the injector rails and it's a right bitch. You'll save an hour and much swearing by removing the rails.
I can't reiterate enough how easy it is to remove those injector rails or how scary it looks if you haeven't done it before. Once you have you can do it in between 5 and 10 minutes.
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Thank you so much to everyone who has replied. I looked at the fusible link and it is neither melted nor broken, so it sounds like the problem lies with the glowplugs. I'll try replacing them and will post with the results.
Thanks again! Kate
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SOLVED! I changed the glowplugs and the car is working great!

wrench and take off the injector rails. Those are the snakey steel lines going from the injector pump to the injectors. <<<<
I ended up changing the glowplugs without taking out the injector rails-- it was tight, but I was able to maneuver around them, and this saved me from having to deal with getting the air out of the lines later. I replaced all 5 with the Autolite glowplugs (they cost $10 each, vs $21 each for Bosch)-- my car manual recommended taking them out one at a time and once the old one was out, turning the ignition for a couple seconds and blowing the air out before putting the new one in. I did this for each in turn, but did not clean the hole out with a brush as has been recommended.
My glowplug light is now working again (it was intermittent before), I am no longer getting thick black smoke when the car starts up, and the engine seems to be running smoother. But most importantly, my car starts first thing in the morning with gusto!
Thanks to all who helped me out- Kate
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