W123-TECH Glow Plug - Lamp Operation

[Grey Ghost]

had all five glow plugs replaced less than 10,000 miles ago. Over the past couple of weeks, I've had to turn the key to the right 2-3 times before the glow plug indicator lamp lights. This morning, the light didn't come on at all, and it was hard to start her.

I can't believe that the glow plugs have already failed...must be a wiring issue, no?

GG is going in for 5,000 fluid replacement in a few days...I'll have Doug check the plugs/wiring at that time

Until then, what do you guys think?

[Grey Ghost]

the next time I went to start the car, I was back to my original problem (needing to turn the key back and forth in the cylinder a few times before the glow plug lamp lit)

p.s. the ignition cylinder is new, also with less than 10,000 miles

[Tom Hanson]

The switch on the back of the steering lock could be the culprit.

[4point5]

How about the glow plug relay? My TD is having weird glow plug issues. The pattern I have noticed- cold (as in sitting overnight) starts are fine, hot starts are fine. Seems when the engine has colled for several hours after having been driven, the glow plug light will NOT go on, meaning I have to crank it until it starts. (Gee, my compression must still be good...!)

Thoughts?

[fnzoo]

How often should you change glow plugs? My 1985 300D has the original plugs and 225,000 miles.

Fnzoo

[Robby Ackerman]

My philosophy is to change them as/when/if they burn out. They are easy to get to on this model. There is nothing wrong with swapping them out one at time as they go, though ususally when one goes I'll replace the entire set. My reasoning right or wrong is that when one goes the time is about up for the others. My mechanic says just change them individually as they burn out. On newer diesels the entire manifold must come off so it makes sense to replace the entire set. I usually get my Bosch glow plugs from Advance Auto and the last time the set ran me $50 or so.

[Sokoloff]

You can test them easy enough. A good plug will read 0.6 ohms. If they are much off of that, I'd change them all and keep the old good ones for spares.

Len

[Tom Gatlin]

Replaced mine at 253K. Bought mine at AutoZone. $10.95 each. Found 4 of 5 bad.
Changed all. OEM Bosch

I tested mine by putting the glow plug on the positive battery terminal then using an alligator clip going from ground to the tip of the glow plug.

If it sparks the the the glow plug is good.

Happy testing

[fnzoo]

Ok. if I get the glow plugs. How do I change them? They look alot like spark plugs is it the same idea? What size socket is required. Do I have to do something with the fuel lines?

Thanks

FNZOO

[Tom Gatlin]

As I recall, a 14mm open on one end ans box ratchet on the other. To take the wire off I think it was a 8mm. Use a wide flat bar to hold the wire to loosen.

Good luck, tom gatlin

[AntonG]

I just acquired a 1982 240D 4spd (178K mi) for $500 that won't start. The previous owner believes that the fuel pump is bad, but fuel flow seems to be normal. The troubleshooting guide that he followed was for a gasoline fueled vehicle.

Records found in the glove box indicate that he had been using ether to start the car for the last two years. There are no records of maintenance other than new tires and an oil change with the standard 5w30 used at the local Pep Boys (over a year ago).

Before worrying about the routine maintenance tasks that have (likely) been neglected, I want to at least get the car starting. Based on what I have read on these forums, I am suspecting the glow plugs, but I'm wondering about what issues I will run into with the injector lines when I change the plugs. Any input would be appreciated.

[blkchambers]

My impression is due to the very high compression ratio of MB diesels and very high volatility of ether, that ether should never be used in diesels. Do a compression check. You may have burnt valves.

[Robby Ackerman]

The glow plugs is the place start. See my post of today under diesels about checking them. Then there are fuel filters, air filter, and valve adjustment. Its all little stuff.

[Maxbumpo]

When replacing glow plugs, injector lines should not be of any concern (other than they're in the way. Leave'em alone, work around them.

Does the glow plug light in the instrument panel come on?

The ether usage is very very bad - may lead to a cracked/broken pre-chamber, which will destroy the engine. :eek: I hope that this damage has not already occurred. I wonder if it would be prudent to remove all the pre-chambers to check for damage??

Calling Doktor Booth!!

[AntonG]

Ok, just a follow up as I got it running last night. Put in four new glow plugs and replaced the primer pump (which was leaking all over the place when you pumped it) and it started in 10 seconds. The car does have some apparent electrical and vacuum issues that I'll be working through in short order, but no smoke in the exhaust and it handles well.

[VLayton]

Ok, just a follow up as I got it running last night. Put in four new glow plugs and replaced the primer pump (which was leaking all over the place when you pumped it) and it started in 10 seconds. The car does have some apparent electrical and vacuum issues that I'll be working through in short order, but no smoke in the exhaust and it handles well.


Sweet! Sounds like a great low-intial-investment W123 score I'm sure will give many hours of enjoyable tinkering.

Best to you,

[pch2021]

you don't find deals like that anymore!

[VLayton]

My womens gets jealous, they tire of seeing all these OTHER w123's getting my attention, TLC, and new shiney parts- so sometimes they throw a fit.

Madeleine, my trusty road warrior 1985 300TD threw a triple whammy at me.

She's been asking for new glow plugs, but every dollar counts around here and so I've been plugging her in below 50 degrees since LAST winter.

If you neglect the glow plugs long enough, these will refuse to start PERIOD.
It seemed she had reached that point, where she could stands no more. SO, I "splerged" on 5 new plugs (sad, isn't it?) and on a lovely December day, I switched them in record time.

Expecting a healthy start, the glow plug relay screamed at me, or, more appropriately cried like a dying giraffe. "Oh *&%#" said I, "what happened to that thing?" I thought perhaps one of the plug wire leads was disrupted, bad contact, and was freaking the relay out. Battery seemed sick, so I charged it until it read full. I had to tow it in for surgery ( car was 15 feet too far east from being in the garage) under the operating lights in my heated open-all-night facility.

I changed the relay with a spare: engttttttttt...

I changed the whole glow plug harness with a spare: engttttttt...

(nice I have all this stuff around, isn't it?)

I noticed the old crusty battery (I don't know exactly where I got it, probably some parts car) seemed to "charge" instantly, so I changed THAT with a spare-
and wah-la! Proper glow system function. Blasted battery.

SO, I switched the relay and harness back to the original equipment, charged the spare battery and she just cranked away- as if the glow plugs were never done and the display lamp of system operation as about as genuine as Milli Vanilli's talent.

Hmmm, it WAS particularly cold here for a couple weeks, and as I haven't run ANY additives in my cars for almost two years, perhaps I was facing my very first gel problem in 550,000 miles of W123 diesel experience. In the cargo area I still had the second half of the degellant I bought for my two running girls to share, destined to be the winter shot of the season, Frasquita got hers, Madeleine was next...

I opened the main filter, emptied it, and filled it with degellant. I got an extra hiccup of life out of it. I poured my last couple ounces in the tank, opened the banjo bolt fitting, and she coughed and coughed, and the battery was drained again so I let her rest overnight on the charger.

This morning, after some crabby hesitation, enough fuel got flowing to get her to roar to life, so I treated her to a nice healthy dose of anti-gel and a tank of fresh fuel.

What a trooper, she deserves it, 254k and ticking, forward, march!!

Point taken, Madeleine, point taken. Now I just have to figure what the heck her sister is whining about. :(

[pch2021]

vince...if you ever need any parts...i owe you a couple presents for what you do up there...if you ever can't slurge agian and need plugs, filters, belts, or any of that other stuff, ask and you shall receive!

i had a simliar adventure today with an '80 sd.

it had stuck valves, and wa sin a bad wreck.

i got her up and going again though.

[VLayton]

That's generous of you, Pierre. Perhaps I will need to buy some odd part off you one day, no need to send any free goodies you need yourself, just send your app in ;) (I still need to get you extra copies) :(

Cheers, Happy New Year, here's to MB enthusiasm in '06!

[pch2021]

i need to do that, dont i? I sitll have it, but what is your mailing address again? :(

i think we will have 3 cars listed: 2 240D's and mommy's CD. actually, if you could send me a bulk of applications [like 10], I have so many 123 owners at hand that I could REALLY REALLY dispose of them. I also offer a $5.00 /hr discount to owners who participate in any MB oriented clubs.

[Grey Ghost]

two or three times in the last ten days (always in the morning, at first use) my glow plug indicator has failed to light as the key is turned and it's obvious that the plugs haven't been operating either.

the plugs were replaced 40,000 miles ago (August 2004)

I'll have them tested at my upcoming 15M Maintenance session, but does anyone have any theories?

Once the car has been started, the plugs operate without fail for the balance of the day...

[dlobacz]

My 300TD just went through that same thing...eventually it just wouldnt start, it turned out to be the 80amp fuse in the preglow relay. I assumed that the odd symptyms were due to its going bad. After replacing the fuse, everything is fine. Good luck, hope it helps

[sbiggers]

Where is this 80 amp fuse located?

[Sokoloff]

Fuse is in the glow plug relay box, the same place the glow plug connector plugs in. It is usually sitting on the driver's side fender well under the hood. Take the cover off and you can see the strip fuse and test the glow plugs at the same time. Can all be done in about ten minutes.

Len

[Grey Ghost]

why would this fuse only fail in the morning?

[VLayton]

why would this fuse only fail in the morning?


The tiniest varience of the fuse structure due to age?

I think the Ghost is likely giving you the early warning sign that the plugs aren't up to perfect par anymore. The symptom will like get worse until there is no light. Whenever this has happened, 5 new plugs solved the symptom.

[Benz 300]

speaking of glow plugs, does something with the glow plug relay or system stay on while the car is the car is running?

[VLayton]

Not unless it has been modified to do so.


(Meade, I undid your purple wire mod, and installed 5 new NGK plugs in Loreli at the owners insistance. Did you see the pic with the Euro lenses at www.club23d.org ? A new OEM hood pad is coming in for her this week too. Did a full in-motor timing chain job last week. 4 degrees to zero. She's hummin'! :) )

[Grey Ghost]

I know everybody will advocate testing the plugs, but is the expected service life of a glow plug?

[Sokoloff]

I'd say a good fifteen years on your car, much less on the 210 diesels.

Len

[Grey Ghost]

in that case it definitely sounds like an electrical gremlin...I'll check the relay fuse tonight...is it really an 80 amp fuse??

[Sokoloff]

But an individual glow plugs can go bad anytime. Still ought to test them.

Len

[dlobacz]

Yup, its 80amp. I found the fuse at a local Mercedes parts/service center for $1.50.

[VLayton]

in that case it definitely sounds like an electrical gremlin


Why? How old are yours?

[Grey Ghost]

mine were replaced en masse in August 2004, 40,000 miles ago

(the problem occurred again this morning...fortunately it's warm enough to crank the car without the glow light and get it going -- hopefully I'm doing any damage using this technique, but I've got to get to work in the morn, don't you know?)

[dan holm]

It's been a while since I've had a 123 Diesel, but I'll give it a shot.

Before or near the relay there exists a flat fuse. It's a simple piece of flat aluminum or thin steel. Possibly there is a small crack in this piece. When the environment is cool, the metal would be smaller and thus make the crack larger. After warm up the metal will expand and make a connection.

In an emergency I have used a little foil until the proper fuse can be obtained.

Sounds crazy, but it has happened to me.

Dan

[Grey Ghost]

that's actually the most plausible explanation I've received...you're referring to the 80 amp fuse I take it

[dan holm]

Since I've run out of 123's, I have nothing to look at. I think it's an 80 amp fuse. Just does not really jump out at you looking like a fuse.

Check it out.

Dan

[Grey Ghost]

got the fuses at the local dealer this morning (he had a whole bunch of them).

$1.90 per...bought two (thanks for the advice, Doktor Booth) and will install one this afternoon

will advise if this is the solution!

[VLayton]

that's actually the most plausible explanation I've received...you're referring to the 80 amp fuse I take it


Sorry I wasn't more explicit. He very clearly explained what I meant...all (at least non-enclosed) fuses are subject to this, forgot not everyone is aware of that. :o

[Grey Ghost]

switched out the fuse Friday night (old fuse looked identical to new).

Saturday morning, got glow plug light and quick start
Sunday morning, no light hard start
Monday morning, light & quick start

I'm starting to think the problem is in the key cylinder, but I always get light & quick start once the engine is warm

[VLayton]

I doubt key cylinder, Skip.

It's hard/rude to ask your tech if he did the job right, but if he didn't ream the chambers and used Bosch plugs (80006) (or less) one or more plugs may very well be shot, even after only 40k. That's all I got with my first plug job (the only one I didn't ream)

I'm not so confident the Bosch plugs cut the mustard anymore, so I'm implementing NGK's to compare the results.

[Grey Ghost]

the part number listed for the August 2004 plugs is 000 159 83 01...assume those are Bosch

ignition switch & lock was replaced in June 2004 (switch part # 202 545 01 04; lock part # 123 462 03 79)

[Maxbumpo]

(Meade, I undid your purple wire mod, and installed 5 new NGK plugs in Loreli at the owners insistance. Did you see the pic with the Euro lenses at www.club23d.org ? A new OEM hood pad is coming in for her this week too. Did a full in-motor timing chain job last week. 4 degrees to zero. She's hummin'! :) )

Vince,

I purposely executed the 'purple wire mod' so that it could be un-done if desired - hope that went smoothly.

Any evidence that any GP's were bad?

Timing chain stretch was 4 degrees already!!! Wow, that chain was very young, and I used almost exclusively M1 oil during it's life. I wonder if I had a defective chain.... :( Did you replace the tensioner?

Glad to hear that Lorelei is running well, and thanks for the news.

Grey Ghost,

Sorry for hi-jacking your thread!

[bro frank]

had this thing melt out the other day. see post titled "melted"

[Maxbumpo]

Here's a picture of the fuse from Rusty's website:

[bro frank]

that's what it isthen, an 80 amp fuse.