New to Diesel - Can't get 85 300TD to start! - PeachParts Mercedes-Benz Forum

Tallakahath · #1 02-09-2010, 12:16 AM

I'm very new to both diesel and this car in general, and after a few hours of google searching and testing things I still can't figure out what's wrong, and I'm a bit afraid to start opening things up without having a better idea what I'm doing... and this forum seemed helpful. If I'm doing this wrong please tell me and I'll go back to searching more.

So, two nights ago I went to start my car and... well, she wouldn't start. Glow plug indicator light went on, hung around, turned off. I turned the key to the ignition position... the engine sounded like it was _trying_ to start, but, the interior light began to dim, and the cranking sound got weaker and less frequent, and then, well, nothing. Tried again. Even worse. Tried again. Won't even bother.

Tonight, tried to jumpstart the car, figuring it was maybe just the battery. Hooked up cables, got car to start! Disconnected, turned off car, thinking it was all good... then decided to go to Autozone to get the battery fully charged. Hooked all the cables back up... couldn't get it to start. At all.

Noticed that, when the glow-plug indicator lights came on, there was this _buzzing_ under the hood. Opened up hood, and it seems like the glow plug relay (from what I can tell) is... making this really loud buzzing. Can't get hi-beams to go on steady during this process, can only flash 'em, and that dims the interior lights even more. Turning on turn signals makes the buzzing click as well, so it sounds electrical. Should I be trying to charge my battery even more hardcore, or, should I look into opening up the glow plug relay box? The glowplugs were replaced within the last 6 months, if that helps, and up until now I've had _no_ problems with the plugs or starting the car.

Help? Advice?

layback40 · #2 02-09-2010, 12:22 AM

Checkyour earth strap & other battery connections. Sounds like your battery is dead as well

Tallakahath · #3 02-09-2010, 12:25 AM

Thanks! I'll try that when it's light outside. Should I be concerned with the loud buzzing from the glow plug relay?

barry123400 · #4 02-09-2010, 02:08 AM

Quote:

Originally Posted by Tallakahath

Thanks! I'll try that when it's light outside. Should I be concerned with the loud buzzing from the glow plug relay?

Not unless it continues when you are sure the battery is charged up and any poor conections are cleaned. The low voltge at the relay is probably causing the issue.

Tallakahath · #5 02-09-2010, 02:48 AM

Quote:

Originally Posted by barry123400

Not unless it continues when you are sure the battery is charged up and any poor conections are cleaned. The low voltge at the relay is probably causing the issue.

Awesome! I was all worried I'd have to blow ~$70 on a part for this. Already gunna' have to put down for new shocks and probably a transmission fix of some flavor, but, that's a problem I _think_ I have a handle on. I'm going to get it jumped tomorrow, then see if I can get me a good full charging, and hope from there. Thanks again!

vstech · #6 02-09-2010, 09:01 AM

if you are having trouble starting the car, and jumping sometimes works, you more than likely have loose belts on the alternator, and or are having alternator problems. I would pull the battery out and have someone take it to autozoo or somesuch and fully test the battery. and fully charge it if it's weak, but good. replace it with a solid group 49 if it's bad.

nckmsn · #7 02-09-2010, 11:16 AM

Quote:

Originally Posted by Tallakahath

I'm very new to both diesel and this car in general, and after a few hours of google searching and testing things I still can't figure out what's wrong, and I'm a bit afraid to start opening things up without having a better idea what I'm doing... and this forum seemed helpful. If I'm doing this wrong please tell me and I'll go back to searching more.

So, two nights ago I went to start my car and... well, she wouldn't start. Glow plug indicator light went on, hung around, turned off. I turned the key to the ignition position... the engine sounded like it was _trying_ to start, but, the interior light began to dim, and the cranking sound got weaker and less frequent, and then, well, nothing. Tried again. Even worse. Tried again. Won't even bother.

Tonight, tried to jumpstart the car, figuring it was maybe just the battery. Hooked up cables, got car to start! Disconnected, turned off car, thinking it was all good... then decided to go to Autozone to get the battery fully charged. Hooked all the cables back up... couldn't get it to start. At all.

Noticed that, when the glow-plug indicator lights came on, there was this _buzzing_ under the hood. Opened up hood, and it seems like the glow plug relay (from what I can tell) is... making this really loud buzzing. Can't get hi-beams to go on steady during this process, can only flash 'em, and that dims the interior lights even more. Turning on turn signals makes the buzzing click as well, so it sounds electrical. Should I be trying to charge my battery even more hardcore, or, should I look into opening up the glow plug relay box? The glowplugs were replaced within the last 6 months, if that helps, and up until now I've had _no_ problems with the plugs or starting the car.

Help? Advice?

Tell us more about how it behaved when you had it charged but it wouldnt start. Slow cranking? Fast cranking? Etc?

tr1cky · #8 02-09-2010, 01:13 PM

It doesn't sound like the GP relay to me at this point. Sounds like an issue with the charging system. As recommended, find out why your battery is losing charge or not getting it back. Could be the voltage regulator or alternator. I've found many times that the culprit is corrosion at a terminal or in the end of a cable.

I say that I don't think its the GP relay because I've been able to start my 300SD with nearly 200k miles down to 10 degrees Fahrenheit without the relay. Mind you it took about 5 seconds of cranking and a bit of extra fuel, but it did start up quickly.

Tallakahath · #9 02-09-2010, 03:47 PM

Quote:

Originally Posted by nckmsn

Tell us more about how it behaved when you had it charged but it wouldnt start. Slow cranking? Fast cranking? Etc?

Sounded just like when I wasn't having it jumped - one crank, a slower crank, an even slower crank... then nothing. The lights still got real dim, and the GP relay box was still buzzing loud as ever. Now it won't even bother cranking, and the lights nearly go out when I try to get it to do such. Also raining outside so I'm not going to try messing with batteries 'till that clears up, since the car is outside...

This whole problem seemed to start rather suddenly, though, to be fair, I'd been loaning someone else the car earlier in the night. So I have no idea if it was having problems on a previous startup. But never before this had _I_ experienced it doing this... cranking slower and slower 'till it wouldn't go at all.

Like, when I first tried to start it that night, it was _almost_ there, but, it got slower and weaker and slower 'till nothing. Tried starting again, it was just going even weaker.

I'll give all the battery-related advice a shot when it stops raining. Of all the times to rain in California, why must it be now?

Codifex Maximus · #10 02-09-2010, 06:02 PM

Yep. Sounds like either a dead or dying battery, no charge on the battery, and possibly a fault in the charging circuit. As suggested, verify all grounds are free of corrosion and are tight. Check for loose belts.

hankthoreau · #11 02-09-2010, 06:11 PM

Ok, so I read the whole thread, and I am stuck here in the EXACT position, a half hour away from picking up my son at school (my mom's on her way) and I am FURIOUS!

Basically, same issue... mine's a 1983 300TD Wagon... have had issues over the past month every few days... I get in, and turns over once or twice slowly, then nothing. NOW, after fiddling with the antenna all day, got it working (well, receiving reception... unplugged it), went to start it up and nothing but this f***ing buzzing from the GP relay box. First time for the buzz. I've jumpstarted it in the past and it ran fine the rest of the time, until randomly, would not start. Tested voltage with everything off at battery... 12.6 or something like that. Turned key on, drops to 7.5ish. Not sure if that's normal. My radios actin' all crazy... dim lights and ****... like there's a cross somewhere, but I'm almost positive there is NOT...

Low voltage would be caused by faulty voltage regulator? Or does that only function when running? Or faulty alternator? or battery? I bought a new one 14 months ago. Just don't get it and am frustrated....

No loose cables or belts... just up and started getting testy on me.

Leavin' it to the pros on this forum... y'all are way too smart to let this one stump you.

Codifex Maximus · #12 02-09-2010, 06:19 PM

Hank,

Take your battery out and put it on a trickle charger. See if that fixes the issue for a while - till it goes dead again maybe. If it does go dead after a while then you've got an issue with your charging.

Also, those ground connection issues seem to keep popping up with posters. Check em out and make sure they are clean and tight.

hankthoreau · #13 02-09-2010, 06:22 PM

Thanks for the quick response...

(1) Exactly which ground connections should be confirmed as tight?

(2) I was reading more, and found that the voltage at the battery posts when running should be 13.5-14.0, and 12.7 fully charged... when it was running last week, it measured 13.6... today, right now, it is at 12.5. When I turn the key, it drops to 7.5. Is that normal?

Thank you thank you thank you....

hankthoreau · #14 02-09-2010, 06:31 PM

Also... the buzzing starts within 2 seconds of turning the ignition on... all gauges act normal, except the tachometer spins up to 6000rpm and coincides with the buzzing from the GP relay....

hankthoreau · #15 02-09-2010, 07:31 PM

Put the battery in my bicycle basket and headed to the battery specialists... they told me it was from 2002... YAH... THAT'S WHAT I SAID................

So, turns out the 'out of the way' mechanic installed a 7 year old battery as new to me last year...

He is no longer in business according to the phone message.

Replace the battery...

Does it start?

To Be Continued....