Today I noticed that my glow plug light was coming on while I was going down the road. It would come on briefly, then go out for a while.

Later in the evening, the glow plug light came on and stayed on. On the way home, my wife noted that the dash lights and headlights seemed "kind of dim".

Shortly after getting home, I went to move the car. The battery was dead. It is an "Interstate 50" battery with the date 12/07 punched out. It was a bit low on two of the cells, so I put a little distilled water in them.

Voltage reads 12.16 volts. A $3 hydrometer says the battery is "dead" (ie, none of the little balls float).

I removed the battery and have it on a charger right now.

I've been searching in the forums, and I'm thinking Glow Plug Relay and/or Alternator.

What do you guys think? Am I on the right track...? What else can I do to zero in on the problem and fix it?

Thanks,

- Patrick

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1982 240D. 198k, Marine Blue/Blue, 4 Speed, Crank Windows, No Sunroof, No Rust, No Oil Leaks
2001 TDI. 197k, Lagoon Blue/Black, 5 speed, Chip, G60/VR6

sounds like a stuck glow plug relay..........those things draw a LOT of current on............something less than 80 amps. And yes that will drain a battery pretty quick.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

When you put the battery back in and start the engine, check to see if the glow plug relay continues to provide voltage to the plugs after the engine starts. The circuitry in the relay should turn off the relay upon turning the key to the "start" position. However, if the relay has failed, then the plugs may remain on. This will definitely kill the battery.

Another way to check it is to setup a voltmeter on the battery. After the engine starts, rev it up to about 1800 rpm and watch the voltage. It should be above 13.5 volts. If it is not, then the relay might be stuck closed. Shut the engine off, disconnect the plug from the glow plug relay that goes to the glow plugs, and repeat the test. If you now get 13.5 volts at 1800 rpm, you have confirmed that the relay is stuck closed and that the alternator is fine.

If you still do not get the 13.5 volts, then the problem is not related to the glow plug relay and the alternator, or regulator, is the likely culprit.

I checked the battery to see if it's charging. I think it's too soon to tell, so I'll just let it charge overnight and check again in the morning. I also looked at the Glow Plug Relay and connections, but I can't tell from looking if it's bad or not.

I don't know if the punch-out dates on the battery mean that it was "bought in December of 1997" or that it is "good until December 2007".

Is an '82 240D "smart enough" to use an illuminated Glow Plug light to signal that there is something wrong (like a bad battery)? My TDI will flash it's glow plug light if a brake light bulb is out. Will a 240D do anything similar?

I'm thinking about getting the Fastlane Glow Plug Kit. It says it's for an '82 240D ,but it has different connections than the one in my 240D does. Anybody know if this one will work in a 240D...? I had to replace the glow plugs in my TDI after 125k miles, and my 240D had 180k miles, so it may be due...

Thanks,

- Patrick

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1982 240D. 198k, Marine Blue/Blue, 4 Speed, Crank Windows, No Sunroof, No Rust, No Oil Leaks
2001 TDI. 197k, Lagoon Blue/Black, 5 speed, Chip, G60/VR6

Patrick,

Please re-read Brian Carlton's advice , He's on the MONEY.



The Beauty of the 82 240D is its simplicity I.E. NO E.C.U. , NO "Chips".
Your electrical "Gremlins" may be causing the interior G.P. to "Signal"
you;But its only a function of the direct connection between the 4 G.P.'s
in the engine compartment + the one in your cabin.

OK - it's morning, and my battery is charged.

I started the engine (fired right up) and measured the voltage across the battery terminals. I got 14.5 volts.

This tells me that my Alternator is OK, right...?

Then I unplugged the two plugs on the Glow Plug Relay, and disconnected the strip fuse - then I checked the voltage across the battery terminals again. I got 14.1 volts.

I think this tells me that the Glow Plug Relay is OK...???

So I don't know if it's the Glow Plug Relay or not. I'm beginning to think it isn't, but I still don't know why the Glow Plug Light was coming on when I was driving

I did some more searching, and one old post that recommended disconnecting a battery cable and checking the voltage between it and the battery. I did that, and I got 12.69 volts.

This tells me that there is a current draw that shouldn't be there, right...?

So I think what I have to do is to monitor the voltage between a battery terminal and cable while I unplug fuses one at a time to identify the offending circuit.

Does that sound right...? Any more advice that can help me...?

Thanks!

- Patrick

__________________
1982 240D. 198k, Marine Blue/Blue, 4 Speed, Crank Windows, No Sunroof, No Rust, No Oil Leaks
2001 TDI. 197k, Lagoon Blue/Black, 5 speed, Chip, G60/VR6

Alternator is fine.

A drop in the voltage, when the glow plugs are disconnected, is not meaningful. You might have been at a slightly different rpm when you made the second check after the plug disconnect. Or, the voltage is dropping slightly because the inrush of current to the battery, right after startup, is falling off.

During all of these tests, did the glow plug light remain "on", or is the problem an intermittent problem?

When the glow plug light comes on, leave the engine running and connect a voltmeter to one of the glow plugs. See if there is any power to the glow plugs when this occurs.

If you wish to look for a "leak" you need to use an ammeter, not a voltmeter. With the engine NOT RUNNING, disconnect the ground cable to the battery and connect the ammeter in series between the negative battery terminal and the ground cable. Most ammeters will not measure too much current, so make sure that everything is off, including keeping all doors closed. You are looking for a value of between 20 and 50 milliamps. Any more than this and you should seek out the culprit. However, it sounds like you have a larger problem than a small leak.

The glow plug light acted normal when I was checking things this morning.

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1982 240D. 198k, Marine Blue/Blue, 4 Speed, Crank Windows, No Sunroof, No Rust, No Oil Leaks
2001 TDI. 197k, Lagoon Blue/Black, 5 speed, Chip, G60/VR6

Clearly, you now face an intermittent issue.

Drive the vehicle and keep the voltmeter handy for when the problem occurs again.

You can't troubleshoot a problem, and make any good decisions, unless the symptoms are evident.

My gut feeling is 90% chance its the glow plug relay, 10% chance its the ignition switch. You will need to catch it in the act with the voltmeter to confirm.

__________________
Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

I have to agree with boneheaddoctor here, I feel this is the realy that is beginning to give you tell-tale signs of faliure. Most of the time its one of the capacitors. If you read this thread... wont start for anything! 1985 300SD you'll see what sady went through to have the glow plugs working correctly. Those relays do draw alot of current!

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Robert Ayala

1985 300SD (W126) 300K miles

Where si the relay located for my SD?

I wish I had a picture right now so that I could up load it, but I dont. However, its fairly easy to locate.....stand in front of the car with the hood open. As you look in the engine bay, you should have an ABS Module/controller on the right hand wheel well hump. Right in front to the right is the Glowq plug relay. It is a black square box. You can't miss it, its fairly large! Let me know if the picture will help!

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Robert Ayala

1985 300SD (W126) 300K miles

It's even easier than that because he does not have the ABS module in the way on the '83. Just to clarify, the glow plug relay is on the driver's side fenderwell, just forward of the wheel arch.

I feel like an idiot

I knew that, I was tryign to ask a differnet question but I asked wrong. When I remember I will post! LOL

I was hearing about some bushings wearing out and need replacments, has to do with the alternator?

I was wondering where these bushings are located??? thansk once again.