Its that point when you stand up and look at your car and think, "....I'm screwed." So I was working on my glow plug issue on My 300TD and I found that the glow plug in cylinder 2 was dead. The wire tested good. I tested the relay and the fuse and all looks good. I went to take the plug out to test it further. Put the wrench on and it wouldn't budge. I soaked it in pb blaster and tried again. I thought I felt it turning, but it was actually rounding the nut. So I tried using more pb, hit it with a hammer and screw driver to loosing it up, tried the wrench again and it just turns on the nut. I tried the splined end of the wrench and still just a spinnin'. I was using 12mm wrenches. I got an 11mm wrench and was able to get it on the nut and tried to give it a turn, but I messed it up further... I'm screwed. Any suggestions. I guess I could take it somewhere and have them remove them all.

Another question. Would one bad glow plug take the whole system down?

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1985 300d smoke silver/red int. (204k) <--Sadie the 80's Mercedes from Hades!
1985 300TD 587 cabernet red/155 Creme (143k)
2007 Ford Expedition EL (54k)

"Seems to me you bought a hobby... not a car" - My dad.

Ok So Which nut did you round off, the nut that goes on the terminal that holds the wire and insulator on, or the one that is on the color of the glow plug body?

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1978 Mercedes 240D
1981 Mercedes 240D
1982 Mercedes 240D

Sounds like someone really tightened those suckers in...or its an original....I would think the only thing that would get it out is leverage....your going to have to get something like visa grips.....to bite on the nut and then turn it....

I have before, taken an American sized socket and tapped it on a striped nut....then used a ratchet and break bar to great it off...

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You Head is Iron so you can heat the Glow Plug with a Propane Torch as hot as you want. Just move all of the items that can burn out of the way.

After it cools down some hit it with the PB Blaster; being warm helps it wick into where you want it to go. The Heating and contracting tends to disturb the dimensions and loosen them a little.

Before you try something like a Vice Grips I would try one of those External Rounded Nut/Bolt Head that you pound over the Head of the Glow Plug extractors first.

When it is time for them to go back in ream or otherwise clean out the glow Plug Holes and use some sort of Neverseize type compound on the threads of the Glow Plugs.

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84 300D, 82 Volvo 244Gl Diesel

[QUOTE=fender_bender;3161037]Its that point when you stand up and look at your car and think, "....I'm screwed." So I was working on my glow plug issue on My 300TD and I found that the glow plug in cylinder 2 was dead. The wire tested good. I tested the relay and the fuse and all looks good. I went to take the plug out to test it further. Put the wrench on and it wouldn't budge. I soaked it in pb blaster and tried again. I thought I felt it turning, but it was actually rounding the nut. So I tried using more pb, hit it with a hammer and screw driver to loosing it up, tried the wrench again and it just turns on the nut. I tried the splined end of the wrench and still just a spinnin'. I was using 12mm wrenches. I got an 11mm wrench and was able to get it on the nut and tried to give it a turn, but I messed it up further... I'm screwed. Any suggestions. I guess I could take it somewhere and have them remove them all.

Another question. Would one bad glow plug take the whole system down?[/QUOTE]

No.
But, if your Engine is having poor starting due to low cranking speed and poor compression (this could be due to the need for a Valve Adjustment) the loss of one Glow Plug could cause a problem.

On the Older Loop/Filament type Glow Plugs when one goes none of them will work because it breaks the circuit or burns the Fuse.

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84 300D, 82 Volvo 244Gl Diesel

I wish it was the nut that holds on the wire. That wouldn't feel like impending doom.

The number 2 cylinder glow plug has the least amount of clearance. The IP is there and something else that is right in the way that won't allow sockets on there. I went a bought a "through socket wrench" today thinking that would help but it just won't fit. I tried getting locking pliers on there, but it's just too close to the engine and it won't stay on there. I guess I'm going to have to remove the injector lines to get some more working room. Thought about running the engine for a while to heat every thing up real good and trying again. Ugh!

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1985 300d smoke silver/red int. (204k) <--Sadie the 80's Mercedes from Hades!
1985 300TD 587 cabernet red/155 Creme (143k)
2007 Ford Expedition EL (54k)

"Seems to me you bought a hobby... not a car" - My dad.

The glow light comes on if I unplug the glow wires at the relay, but If they are plugged in it doesn't come on. I do want to do a valve adjustment on both vehicles. I need to get the valve wrenches off my buddy and order valve cover gaskets.

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1985 300d smoke silver/red int. (204k) <--Sadie the 80's Mercedes from Hades!
1985 300TD 587 cabernet red/155 Creme (143k)
2007 Ford Expedition EL (54k)

"Seems to me you bought a hobby... not a car" - My dad.

You can pic a good spot on the front of the Fuel Injection Pump Flange and scribe a nice deep mark a cross the Aluminum part of the flange and onto the Engine block.

After You have clearly marked the Flange and Block You can remove the Fuel Injection Hard Lines and loosen the 3 Front Fuel Injection Pump Flange Nuts and the bottom Rear Nut and Bolt and Rotate the Fuel injection Pump so you have room.

When you are done rotate the Fuel Injection Pump back and line up the marks you made and tighten up the Fuel Injection Pump Bolts. That will return the Fuel Injection Pump back to the timing you had when you started.

With the Fuel Injection Hard Lines off you can use regular Wrenches to do the Valve Adjustment with the exception that one of the 14mm or 9/16" Wrench needs to have the Head Thinned to about 1/4" (The Hazet Valve Wrench Head thickness = 0.242; 1/4"= 0.250) to use on the bottom Nut.

When you re-install the Fuel Injection Hard Lines leave the Line Nuts at the Injectors a little loose and crank until Fuel comes out to bleed the Air out of the Lines before tightening them.

If you are going to continue to use regular Wrenches you should use a 6 point Socket or I have seen some Combination wrenches where one end has a 6 point box end.
On the no good number 2 Glow Plugs you could cut the threaded terminal end that the little nut screwed onto off so you would have more room to get a Socket on.

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84 300D, 82 Volvo 244Gl Diesel

Got it. Thanks! Used heat and a nut extractor set that I forgot I had (in different tool box).

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1985 300d smoke silver/red int. (204k) <--Sadie the 80's Mercedes from Hades!
1985 300TD 587 cabernet red/155 Creme (143k)
2007 Ford Expedition EL (54k)

"Seems to me you bought a hobby... not a car" - My dad.

Sweet

Now just make sure to ream the holes and use Bosch branded plugs....then your set!

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I can remember I have things but remembering where I put them is the problem.
I guess that means you got them out.

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84 300D, 82 Volvo 244Gl Diesel

Be thankful.

Although this is a gas engine with spark plugs, the task is far worse than yours and consumed five months. It was, by far, the most difficult job that I have ever done on a vehicle:

http://www.peachparts.com/shopforum/open-discussion/332018-little-tuneup.html

I see a couple of mistakes on this thread.

First, YES a bad glow plug can affect any system, but affects the later systems less. I know, as number five is out, and in the "winter" had to plug in the block heater for a bit. Otherwise she would run on four until enough heat for five to come on.

Second, do not use Bosch glow plugs! They are junk! Went bad in a few days to a month. Got a box of Beru to install, just haven't done it because I need the tool and summer is here.

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Current fleet:

1985 Mercedes-Benz 280TE - Waiting for heart surgery.

1985 Mercedes-Benz 300TDT - Rear ended 23 September 2016 and now looking for a new home.

1979 Mercedes-Benz 300TD - Parted out.

1964 Volkswgen Beetle - Vater's since September 1968 and undergoing a restoration.

1971 Volkswagen Sunroof Squareback with F.I. - in need of full restoration.

1971 Volkswagen Squareback automatic with F.I. - Vacationing with her caretaker until he is in better health.

The things that Bosch makes are manufactured in a Factory like other Parts are. Even the best Companies Occasionally have some bad items. So I think one problem does not make all of their Glow Plugs Junk.

From what I have read on the Forums I guess somewhere around 95% of the Members are using Bosch Glow Plugs. So Bosch Glow plugs seem to have a good service record.

All of the Bosch Glow Plugs I have bought from the same Seller are made in France. They have been in My Car for about 5 Years with no issues (I pull them once in awhile and ream out the Carbon).

I have read of Bosch Glow Plugs being made in India; but have not read any of the Members coming across any those. But, it is not impossible the Mcparts places are selling those or some eBay sellers.

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84 300D, 82 Volvo 244Gl Diesel

The OP's question "Another question. Would one bad glow plug take the whole system down?"; seemed pretty clear what He was asking about.

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84 300D, 82 Volvo 244Gl Diesel