I've been experiencing a sporadic battery drain for a few months now, that comes and goes. My battery is new as of Oct. '10, and my alternator was replaced in December. My grounding strap is fine. Last night after my car was sitting for no more than 10 minutes (after driving around fine, starting fine all day) I experienced total battery failure... the ignition didn't even turn over and lights barely came on. Friend jumped the car, on the drive home my lights got dimmer and dimmer.

Today as I had my car jumped I heard a dire buzzing coming from the glo plug relay, which eventually stopped and was not heard again. My Mercedes expert friend and I charged it up, checked the battery (multi meter) and alternator (tightened the belt, even) which charged when I revved the engine. Drove her around a while, came back, and discovered that the culprit was the glo plug relay (unplugged it and battery stopped crazy draining), and what's more the alternator stopped giving me Any charge. Needless to say, I unplugged the glo plug relay.

Is it possible that the glo plug relay problem wrecked my alternator? I've already ordered a replacement, but haven't yet ordered a new gp relay.

Can you think of any other scenario that might be causing this/these problems? Is the relay box something I can open up and fix? The fuse in the box was fine, by the way.

I haven't done any other testing of fuses, etc, (and all fuses look OK).

Any opinions welcome, and thank you in advance

Polly


He speculated

how long did you drive it around? you might have an afterglow relay in there, that is keeping the relay on for 3 minutes... or it could be bad.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

But it did not blow the fuse ?

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Check that new battery out. Batteries are always suspect. Take it back to where you bought it and tell them it's no good, they will give you a new one. They can take some voltage and act like they are charged when really there is nothing in them. Put a little load on a battery like that and you find there is nothing in it.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

I'd also recommend having the old alternator bench-checked if possible before sinking the cost of replacing it (assuming you can return the already-ordered replacement).

The sequence of events you describe is complicated and isolating the components may save you trouble.

You may want to check the inputs to the GP relay, too.

http://www.aa1car.com/library/charging_checks.htm

PM sent.

vstech: I drove it around long enough to charge it, 20 minutes or so at highway speed.

leathermang: Nope, it didn't blow a fuse.... neither the one in the fuse box nor the fuse strip in the relay box itself.

junqueyardjim: I have thought about the battery, I know they can be funky, maybe what I'll do is borrow a known good battery from my friend and see how that goes. I've used the voltmeter on it, though, and it tests and behaves normally when all is (or was) good, so I don't think it's funky.

Yak: thanks for the link, it looks good. I am getting the alternator for free, the warranty covers it... the new ones look so cheap next to the original that it replaced, tho. Still have to remove the old one and install the replacement which is a pain in the @ss.

I did manage to have someone jump it a few hours ago and it took me 16 miles, and jumped again from the place I was and took me home with lights on for a short bit, didn't use them til I had to.

But here's another thing, don't know if it's relevant, but I found that the horn doesn't work since this happened. And another thing I did not mention, my back-up lights didn't work for the past few nights.... I checked the fuse (one of the new copper ones) and it's fine. I seem to be having random electrical failures going on, it's weird, but I am sure that if I'm patient I can solve it.

The bottom line is that the alternator is not charging the battery.... just wanted to reiterate this. I think there are some ground wires I could look at, I reckon. I have only eyeballed the grounding strap, but did not mess with it to see if it was loose or dirty. Still doesn't explain the glo plug mystery.

By the way, I have had problems with the battery draining after continuous heavy rain and dampness, as if the wet is shorting something. It's hit or miss tho.

Horn and backup lights are fuse 14. I'd doublecheck it. How's your aux fan? That's also on that circuit. Motors can be high draw... maybe it's acting up/seizing/bad bearings...

I'll check that fuse tomorrow when there's light. By auxiliary fan, do you mean the heater fan? I still have a few of the old fuses, maybe it's one of those.

I meant the electric fan in front of the radiator, but on further review that might be bad info for the '82 240. I was going from memory on an different electrical gremlins thread.

But - and this'll be a speculation warning - the horn/backup lights/GP relay might intersect at one spot. Tracing an '81 240 wiring diagram, the horn and backup lights are on fuse 14. The backup lights are controlled by the shifter selector switch on the tranny - that also connects to the GP relay (can't start the car unless it's in P/N and the light comes on in R) and also direct to the battery. So....speculatively...check for a loose or chafed wire on the tranny or a bad selector switch. I can't say why that would kill an alternator though.

In that same speculative vein and maybe connecting dots that shouldn't be connected, that part of the car would get wet easier.

Disclaimer: this is looking in the book, not at a car, so maybe a wild goose chase.

this is starting to sound like classic wallmart fuse failures...
the autoparts store fuses SUCK! they are plastic body with aluminum elements... pop your fuse box and if you see white on the fuse contacts... PULL ALL FUSES AND REPLACE WITH DEALER/FASTLANE FUSES!!!

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Check your voltage while the car is running. Then while it's running unplug the glowplug harness that goes from the relay to the glowplugs. If you suddenly gain voltage you have isolated your problem. Sticking relay keeping the glowplugs energized. No alternator will be able to keep up with that current draw and yes, you can cook the alternator in short order. Fairly common.

__________________
'70 F100 shortbed
'82 Diesel Westy
'83 Euro 300TD
Curtlo Viper
Yeti ARC
Surly long haul trucker

Thanks! That tells me what I need to know about the alternator getting fried!
Yes, we pulled off the glowplug harness while checking the voltage, and the massive drain stopped. We had also noticed that the battery wasn't charging back the way it should (pointing to alternator) and after driving it a bit and rechecking alternator (with glowplug harness unplugged, of course) it wasn't charging at all... alternator just dead, and your post confirms that possibility.

Obviously the battery is OK since I was able to drive for about a half hour without its getting a charge, with lights for a part of that time (didn't test my luck for further driving). And this morning all the electrical but the starting is nearly perfect (power windows, lights, etc.)

vstech, I already replaced almost all of the fuses with good copper ones, and always check for corrosion when things go amiss. But I haven't gone back in there since these posts to recheck the fuse for horn and back-up lights.

Yak, thank you for the informed thoughts, I will check out the wiring if I need to. And once I get the car going I will check the fan, though the engine heat has been stable in the past few days through all this.

I am going to borrow a working gp relay box from my friend (while I look for a replacement) and replace the alternator when it comes in, hopefully in the next few days. I'll get back to you all to let you know the results... Thank you very much for all your very helpful replies!

OK, all is well. I replaced the fried alternator, and also the glowplug relay. Now it's charging up perfectly.

The horn and back up lights was Indeed the fuse 14.... I'd replaced Almost all of my fuses with the new copper ones except for a few, including that one. I took it out and with sandpaper got the corrosion off and it worked, tho I am definitely going to replace it.

Thanks for your help, everyone!