That's a pin to help you get the wheel seated on the hub. It screws in place of a lug bolt. It's much bigger than a glow plug.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

That solves that mystery, thanks - useful too, will give that a go next time wheel swapping.

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

Yes, I had read Maxbumpo's description of the removal of his glow plugs earlier this year--in fact, I had printed out his description and had it taped up over my workbench and used his list of tools and parts as preparation for my own attempt.

What I hadn't done was read the second page of the topic carefully. I note now that Eswhwab had mentioned seeing a recommendation for the same Snap-on socket I listed.

Funola's posting there regarding the failure of the plug to seat properly as cause of the buildup of carbon and tar on the shaft of the glow plug makes perfect sense and I will have to make sure that I get the seats clean, ensure they are undamaged, and torque the plugs correctly. I also agree with his assessment that, with proper seating, the plugs should be able to be removed easily, which is what I found on my engine for the three plugs that showed absolutely no carbon buildup on the body. As I said in my original note, it was as if they had been installed yesterday. I will probably coat the entire glow plug shaft from threads to seating area with high-temp anti-seize.

One thing I did not note in my description was that I had plugged in my block heater (the internal one at the back of the engine on the passenger side) and had let the engine warm up before trying to remove the plugs. I left it plugged in during the entire process. Engine temp gauge showed just under 60C--assuming that's the line on the gauge between 40 and 80 degrees--and the engine was quite warm to the touch. Also, knowing the precarious condition of the wiring harness, I did not touch the wiring except to disconnect the glow plugs.

Thanks to everyone for their suggestions, recommendations and comments! I'll post again when I get everything back together and the engine started so I can finally exhale. I need to round up a number of parts before I can complete it. Still looking for the engine wiring harness, but no longer doing it optimistically...

Regards,
Tom
Closter, NJ

Carbon is not supposed to get past the sealing shoulder on the Glow Plug EGR or not.

My best guess is that either the Glow Plugs were not tight enough to seal or there is some issue like warping of the aluminum that broke the seal. That is assuming the head had no defect when it was made.

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84 300D, 82 Volvo 244Gl Diesel

On three prechambers with interference issues, I was going to try a stiff wire brush with a frequent shots of the carb cleaner before the reamer for the tip. I looked down the bores with a flashlight, but couldn't really see anything. I'm going to try to find a small light that might fit into the bore or, perhaps, a friend with one of those mini cameras on a stalk designed for just this sort of inspection.

The glow plugs themselves did not seem to show any damage at their mating face with the head, but that's not to say there isn't some damage down there. My guess is that that they weren't tightened down enough, which would be ironic since the glow plugs that are difficult to get at were fine--some good luck for a change.

Regards,
Tom
Closter, NJ

Ran into this same "stuck" gp myself on the OM606.912 in our '96 E300.

I recently replaced all the glow plugs on this engine. I bought the Hazet reamer and used Bosch glow plugs which I torqued to spec. Today I pulled the intake and removed the injectors to have them serviced and I noticed that the high temp anti-seize I used on the #3 glow plug appears to be blown out of the hole. Seems there is a compression leak on this one. This particular GP was a PITA to remove when I replaced them, while all the others were easy.

Thank you Compu_85 for posting the link to that video of the British chap removing and installing glow plugs in the OM606. I'm going to use drill bits to clean out the bore and the seat per his suggestion. We'll see how it works.

Attached Thumbnails

 

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- Greg -
1973 220D, The Prodigal Benz
1974 240D

I came up with a solution for cleaning carbon off the sealing seat where the glow plugs seal right behind the tip. I didn't like the idea of using a drill bit for a couple reasons. The angle of the bit's cutting edges would not match that of the sealing seat, and the drill bit would likely remove some material from the head in the process of using it.

I made a tool out of a dead glow plug. Using a glow plug to make the tool has two advantages. The angle of the old plug's seat matches the angle in the head, and the finished tool would not have any risk of actually cutting into the head's material, unless pressed really hard against the seat.

First I cut the tip off leaving just a little protruding from the outer shell of the glow plug. I then cut two notches into the sealing seat using a cut-off wheel mounted to a Dremel, angled back a little to create a cutting/scooping edge. I used a wire wheel mounted to a bench grinder to clean off the burrs raised up by the grinding, to leave clean working edges. I also ground off the threads so the tool could be inserted all the way to making contact with the seat, and then rotated while in there.

After running the Hazet tip reamer through and using a wire brush to clean out the hole between the tip and threads, I then inserted my home made tool and used a socket on an extension to press the tool into the seat and rotate by hand. I used a deep well socket that I shortened so it would not bottom out on the head, allowing me to press and turn the cleaning tool at the same time. I did this three, maybe four times, pulling the tool out, clearing carbon from the notches in between goes, until the tool came clean.

Sure enough, I managed to remove a fair amount of carbon from the seat that was left behind after the previous reaming and wire brushing. I was able to shine some light down the hole and I could see the nicely cleaned seat down in there.

Hope this idea helps someone else!

Attached Thumbnails

   

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- Greg -
1973 220D, The Prodigal Benz
1974 240D

That's excellent thank you for sharing,

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

That tool screws into a wheel bolt hole and is used as a guide when replacing wheels. It keeps the wheel on the hub while you reach down for a handful of bolts.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Well, just finished bolting the last bit back on the 606 tonight and the long glow plug adventure is over, at least for now. Not a difficult job and well within the capability of a minimally experienced DIY-er since I was successful in completing it! I do have a question. Actually two.


When I started the engine after reassembly, the glow plug light on the dash board came on as it should, but stayed lit for only four or five seconds. The car had been sitting in a 65F garage all day. Is the glow plug bulb cycle time controlled by the internal temperature of the engine or the external air temperature? Seemed to turn off very quick, tho it was warm. I don't recall what it had done previously since for the past couple of months I didn't get the light until after the car started.


Despite some assiduous searching, I had no luck in tracking down a later glow plug wiring harness--the search was one of the reasons the job took so long since I was loath to reassemble if I had to undo it all again relatively soon. So I'm in the market for a used harness. It can be the early variety with the part number ending in 3932. I'm going to have to have the harness recreated and I'd like to have a loom I can provide to whomever does the job so I don't need to lose the use of the car for any length of time. If anyone has one for sale, please let me know.


As I was cleaning up this evening, I tested the old glow plugs with a 12V ready pack. Five of them lit up readily and glowed brightly, one didn't. With 135K on the car, I'm happy to put the new ones in since I don't know when these were changed last--and the whole issue of snapping them on removal was avoided. Is there some other way to test these to see if they are reasonably good enough to use as spares?


Thanks to all who offered advice and suggestions to me. Much appreciated!


Regards,
Tom
Closter NJ

You glow lamp is behaving correctly. When it comes on after not during a glow cycle that indicates a failed GP. The time of glow is based on a water jacket temperature. Can't help with the wiring harness but they do show up on ebay every so often. The tips of the GPs should glow then they are good.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

That brings up another question I had when my glow plug problem first started. Although the glow plug light doesn't come on until after the engine fires, I wondered whether the good glow plugs light up during the normal pre-start sequence? Or do they light up after the engine starts when the dash light is on? Or do they all not work when one or more are bad?

Regards,
Tom

Fully operating system - once key is in position 1 glow lamp turns on once it goes out you are good to start.

This is where I'm trying to rember a flashing lamp indicates a fault during the wait time. If the lamp goes on after a start that indicates a short circuit the relays have an automatically resettable circuit breaker.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

When the Key is in the pre-glow position the Glow Plugs will remain on until the timer shuts them off or you turn the Key to start (as an example because you watched the glow Plug light and it went off).


How long the light and maybe the timer stay on is determined by the temp sensor.


While you are cranking the Engine the Glow Plugs are on as there is a Jumper Wire connected to one of the Starter Terminals that keeps them on.


I don't know if your year and model has the after glow feature. So someone else can post on that.


The reason your glow plugs are on during cranking is that the Glow Plugs in cold weather get hotter then the heat of compression could do in cold conditions.

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84 300D, 82 Volvo 244Gl Diesel

Gmog....can you share what Hazet part number the glow plug reamer is?
Thanks!

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1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)