No Glow Plug Light - W210 - '97 E300D - PeachParts Mercedes-Benz Forum

treiberg · #1 12-26-2010, 12:39 AM

Car has been sitting in garage for a few weeks while I've been driving my other cars. Temp is about 50 degrees here in Central CA. Went to start car tonight and turned key but got no glow plug light. Turned engine over a few times, then tried again, but won't start. Didn't try too long, as I wanted to get in here and read on the forums.

Seeing many articles where the GP light will intermittently come on after engine is running, which indicates a bad plug, but not seeing any articles for my model where the light is not coming on at all. Makes me suspicious of the relay, but don't want to spend that $100 if it is something else.

What diagnostic should I be doing next? Car was working fine before I parked it a few weeks ago.

By the way, in warm weather climates (it is quite warm here in Bakersfield most of the year), are glow plugs even necessary? Evidently they help a great deal when temps are below 60-70 degrees.

NJ300sdl · #2 12-26-2010, 06:25 AM

See if the glow plug relay is getting power. My 1987 has a flat metal fuse under the relay cover. Do not know what yours has.

layback40 · #3 12-26-2010, 06:34 AM

When you turn the ignition on do you hear the relay click on then off a while later?
Towards the end of the cycle you should be able to feel some warmth on the end of the GP.
If you have a volt meter, you should get a voltage more than say 8v at each plug when you first turn the ignition on.
The strip fuse is a good place to start if you find things are dead.
I once had a spider find its way into the relay box, it fried & then stopped the contacts working. I cleaned them & all was good.

Gp's are important even in warmer weather as they make it a bit easier on your battery & starter motor.

Good Luck !!

Jim H · #4 12-26-2010, 07:09 AM

Quick, easy check if you don't have a voltmeter. Turn on the 'dome' light, turn the key ON and watch the lights. If the relay is energizing the glow plugs the cabin lights should dim. Some minutes later you may hear a faint 'click' when the relay de-energizes and the cabin lights should get a bit brighter.

treiberg · #5 12-26-2010, 03:25 PM

I am getting 12V into that relay, but cannot get 12V at the individual plug outputs. Also, no click on the relay, no cabin lights dimming.

Once I played around with the relay and the other connector, the one that must energize the relay, I got the glow light on and the car fired up immediately. Then after a few starts, no glow plugs - jiggled around wtih it, then I got a light again, and the car started.

So...it appears that either the relay is bad or the input signal to the relay is intermittent. Are there any other control circuits that would impact that circuit that energizes the relay? Maybe just bad connections at the input. I may just pull the relay apart and clean things up and then put things back together again and see what happens.

I know one thing, there is no way that car will fire without the glow plugs, at least at 60 degrees ambient. Once the glow plugs heat, even for a few seconds, it starts easily.

On a side note, what is different about these W210's that causes them not to smoke? I fired up the car in a closed garage for a couple of minutes, and I almost smell no diesel exhaust or smoke, it burns really clean. If I do that with my 240D or 300SD, that garage is filled with nasty smoke in about 60 seconds. Pretty impressive on the E300D!

ROLLGUY · #6 12-26-2010, 04:13 PM

Quote:

Originally Posted by treiberg

On a side note, what is different about these W210's that causes them not to smoke? I fired up the car in a closed garage for a couple of minutes, and I almost smell no diesel exhaust or smoke, it burns really clean. If I do that with my 240D or 300SD, that garage is filled with nasty smoke in about 60 seconds. Pretty impressive on the E300D!

My E300 is the same way. I have not seen much if any smoke from the tailpipe. The 606 seems to be very efficient and clean burning (most likely because of the 24 valve head).

Jim H · #7 12-26-2010, 04:24 PM

Quote:

Originally Posted by treiberg

I am getting 12V into that relay, but cannot get 12V at the individual plug outputs. Also, no click on the relay, no cabin lights dimming.

I'm guessing now, since I haven't opened up a W210 relay, but - is the strip fuse, might be shaped like a flat squared-off letter "C" under the cover of the relay, intact? You might have to look close to see a crack. or take it out and see if it falls apart..

Parrot of Doom · #8 12-27-2010, 05:40 AM

Perhaps something like this is your problem:

They should look like this:

treiberg · #9 12-27-2010, 10:31 AM

Interesting pictures, how did you get the box open? Mine is sealed.

I think my problem might be different because it appers to be intermittent. If my fuses were burned up like that, it would never work.

But I am still tempted to open up my relay to have a look around inside.

jmbeam · #10 06-28-2011, 01:15 PM

Can someone show me a picture on where this glow plug relay is on a w210 model? I have a 1997 E300D. Thanks

Jeremy5848 · #11 06-28-2011, 01:23 PM

It's on the left inner fender, next to the ABS pump and behind and to the left of the windshield washer reservoir. AFAIK, it's the "standard" location for the preglow relay in every Benz I've ever seen.

BioPOWER · #12 11-25-2012, 03:34 PM

Quote:

Originally Posted by Parrot of Doom

Perhaps something like this is your problem:

How did you disassemble your relay? Looks like mine's sealed shut.

KarTek · #13 11-25-2012, 06:18 PM

I got mine open with a knife I think. Basically digging away at the sealant on the bottom until it can be pried apart. Then, gluing it back together when you're done working on it.