1983 Mercedes 300SD Won't Start


bpopilek
10-25-2004, 04:08 PM
Hello everyone, I am hoping to get some ideas on what my problem could be. I have an '83 300SD that started acting up last week. My first problem was that I had not realized I was low on gas because my fuel guage got stuck, luckily this happened in my driveway. After playing around for several hours and adding gas to the tank I was able to get it started again and everything seemed fine. Later that day after the car had set for a few hours I went to drive it and it had a hard time starting, but did on the 3rd attempt so I didn't think much about it. The real problems began the next morning when I went to leave for work. I noticed that the glow plug indicator was not lighting up and no matter how hard I tried, the car would not start. I have checked all of the fuses and do not see any blown at this time. When I do crank the car over it sounds like it wants to start, but it just won't. I know that I am now getting gas to the engine and I smell a very thick exhaust when I get out of the car. Does anyone have any ideas why the glow light shut off and it will not start? I am assuming at this time it is something to do with the glow plugs, but I am not familiar with how diesel engines work, only gas. Thanks in advance!

Brian

bpopilek
10-27-2004, 07:27 AM
Well, since I didn't get a reply on here I did some more looking into it and was surprised to find that the battery took a dump. Just not putting out enough cranking amps I guess. So, thanks anyways.

bpopilek
10-29-2004, 02:16 PM
Well, that was not the total solution I was looking for. The new battery does help considerably, but I am still getting no glow plug light unless I turn the key on and off about 2-3 times. When I do try to start the car, I have to crank it over for 1 to 2 minutes to get enough heat built up in the engine for it to want to fire and run on it's own. How do you check the glow plug system? Thanks!

podunk
10-31-2004, 06:16 PM
trying to second guess and test the glo system on these cars can be too confusing :screwy:

i myself chased a phantom problem for weeks in a 300sd glo sys that left me bonkers :banghead:

i finally found this forum and hooked up with a MB tech type guy that convinced me that the only way to positively check the system is to pull out each glo plug and watch them glo a nice brite red glo.

:disappoin although i whined in disbelief because i had already replaced the plugs with new ones

it turns out he was absolutely right the entire set of 5 new plugs were bad and there was nothing wrong with the glo sys

i also learned that when u turn on the key to the point where the glo light comes on the plugs will continue to glo untill the car is started or untill the key is turned off
this means when when the glo system light comes on and u do not start the car the plugs will burn up if u leave the key on

nave488
11-22-2004, 01:04 AM
i myself have an 85 mercedes 190d and have become practically an expert on those damn glow plugs, the trick with the glow plugs is- the reason the indicator on your dashboard wont light up is (on my 4 cyl) more than 2 plugs are bad, to find out which ones are loose/bad just unplug the glow plug time relay and test each terminal's conductivity to ground, when a glow plug burns out it is much like a light bulb, the broken coil inside causes it to loose it's path to ground therefore not allowing it to heat up.

bpopilek
11-22-2004, 08:21 AM
Thank you for your reply! I already bought 5 replacements and that seems to have solved that problem. But, I know what to look for the next time I run into this problem. :) Is it necessary to replace all the glow plugs if only 1 or 2 burn out, or can you just replace the bad ones? Thanks again!

podunk
11-22-2004, 08:55 AM
yes you need only replace the bad ones

j_hef
11-28-2004, 03:21 PM
yes you need only replace the bad ones

you can do this, but glow plugs tend to burn out relatively close to each other. I used to do this and one by one all 5 of my old ones burned out within 4 weeks of each other. One thing you absolutely NEED to do when you have it out is to use a reamer and clean the carbon from the prechamber. If carbon touches the new plug, it WILL burn it out. You can get a reamer from your MB dealership or snap-on, etc

for easier testing of your plugs on these, take a test light, clip it to one of the fuse screws on your glow plug relay and touch it to each of the 5 lines to your plugs. If it lights, its good, if it doesnt, its bad. Doesn't get any easier than this.

podunk
11-29-2004, 08:52 AM
yes they do tend to go at the same time sometimes , however testing as you say it can lead you astray ie: if a bad plug with the element inside laying against the inside of the case, the test light will come on and show the plug to be good , I have seen this more often than not the tester can also fool us through feedback like i stated earlier in this post ALL 5 of mine tested good, yet all 5 were bad

Again my feelings were too hurt :disappoin but the only shure way no doubt is to watch them glo a nice brite red orange glo.

gmitch50
12-04-2007, 09:45 PM
yes they do tend to go at the same time sometimes , however testing as you say it can lead you astray ie: if a bad plug with the element inside laying against the inside of the case, the test light will come on and show the plug to be good , I have seen this more often than not the tester can also fool us through feedback like i stated earlier in this post ALL 5 of mine tested good, yet all 5 were bad

Again my feelings were too hurt :disappoin but the only shure way no doubt is to watch them glo a nice brite red orange glo.
OK do you need to ground the plug to make it glow or should it glow isolated?
Also, how do you trouble shoot from there to make sure the circuit is good?

chavette
12-06-2007, 10:47 AM
Yes faulty plugs are usually the cause when that happens, make sure you get them tested regularly. I have a BMW myself, but have been thinking of switching to a Mercedes... then i saw this post! Does this kind of thing happen regularly? I always thought Mercedes was slightly more reliable than BMW. What do you think? I created a poll on the subject, please vote if you prefer Mercedes or BMW: link removed by Moderator

'97ventureowner
12-09-2007, 03:16 PM
Please check the dates of the threads and posts and avoid posting in those older than 90 days since the last post. This one's over 3 years old.
Closed.

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