Starting Problem 300D - PeachParts Mercedes-Benz Forum

dgarcia · #1 10-25-2004, 11:33 AM

Help!! I've replaced the alternator in my 85 300D. Otto will not start. I changed both the fuel filters and it just occurred to me this morning that I may have a bad glow plug. I noticed yesterday that the glow light only lights for about 3 seconds. I can hear the relay click about 19 seconds later. Is that indicative of a glow plug problem? Just some history, this car had a bad leak from the pipe just below the egr and had covered the engine in soot. We cleaned the engine in order to make it easier to replace the alternator (and the broken pipe) and I'm wondering if in the process a glow plug could have shorted out. The car's been out of commission for a month now and it's driving me crazy. I replaced the glow plugs about 2 years ago. I've also had to recharge the battery which is only a year old (Sears International). The battery will hold a charge, but in the process of trying to start the car it's died out. Also, some idiot mechanic hot wired the auxillary fan so it starts running immediatley upon turning the ignition key. I disconnected the fan, since I suspect it's just the temp switch that's bad. Don't need the a/c right now Texas is getting cooler. Any and all insights would be appreciated as I love this car and don't want to have to park it or get rid of it.

tangofox007 · #2 10-25-2004, 01:35 PM

Your glow plug situation seems within normal limits. Did you bleed the fuel system after you changed the fuel filters?

dgarcia · #3 10-25-2004, 01:54 PM

Not entirely. It started to rain just as I was bleeding the system. However, I attempted to start the car and it almost started. I didn't see any bubbles when I was priming the pump. I've always hit the pump until no more bubbles are seen coming from the top of the filter. Is it normal for the glow light to shut off so quickley? That's what seems so suspicious. The starter BTW was replaced on this car 6 months ago.

tangofox007 · #4 10-25-2004, 02:07 PM

The glow plug light only remains illuminated for a few seconds. The relay continues to apply power to the plugs after the light extinguishes. (Until the relay clicks.) You might try cycling the plugs a couple of times before engaging the starter. My '82 300D seldom starts right up after a fuel filter change. Despite my best efforts at bleeding air from the system. A weak battery is not going to help the situation, either.

dgarcia · #5 10-25-2004, 03:50 PM

On the auxillary fan issue, where is the switch that controls that fan? I think the a/c quit during the hot summer months and in order to get the a/c working, it was hot wired so the fan would start upon turning the ignition key. I disconnected the wires next to the evap and the fan doesn't start now. But I'll eventually have to fix that. The compressor unit is only 1 year old. It seems whatever controls the aux fan is the problem. On the other issue, I'll recharge the battery tomorrow morning and bleed the system thoroughly and keep my fingers crossed.

Ironforger · #6 10-25-2004, 07:59 PM

Dude, What did you do first, replace alternator or fuel filters? Fuel filters are a ***** if you didnt prime them first. In my opinion, thats your issue, especially since you noted that it sputtered. Put a battery charger on it and crank it until it starts, but dont lay into it. Give the starter a chance to cool off. Keep doing it until it starts and runs smooth.

dgarcia · #7 10-26-2004, 01:22 PM

Ironforger,
I replaced the alternator first breaking the adjusting bolt in the process. That forced me to let the car sit for another week and once that was all in place I tried to start the car. Since it wouldn't start, I replaced the filters. I'm charging the battery now and just noticed this morning that a couple of the braided bypass lines for the injectors are shot. I'll replace them before I attempt to start her up again later today. I did notice that when I tried to start Otto last night, it almost came to life. I'll prime the pump heavily before attempting again later. Have limited time to work on Otto, but refuse to give up. I'll post my results.

dgarcia · #8 10-31-2004, 04:11 PM

Well, I added 5 gallons of diesel, primed the pump about 75 times, (hands still smell bad), recharged the battery only this time I charged it all night. And Otto finally started with big belch of smoke. Still have a little bit of run-on when you turn the ignition to off. I'll find the leaking vacuum line later. Right now I'm just happy the car's running again. There is no better site than this one when you're trying to save money being a DIYer. Over the years I've always found the answer to what ever problem I've had and if I can't find it I simply ask. Eventually, I get an answer that leads me in the right direction. Next step with Otto is replacing the temp switch for the auxillary fan and new brakes. Easy stuff. I think........................