Stuck Glow Plug from Hell! - PeachParts Mercedes-Benz Forum

dsmess · #1 12-21-2002, 07:34 PM

The 300TD was running a bit roughly at startup, so I checked the Glow plug resistances. Aha, #3 is open! Expecting a 20 minute relaxing job, I applied the 6 pt 12mm socket and a fair amount of torque.... and promptly rounded off the end of the glow plug....apparently, I did not quite have the socket fully seated on the thing. I tried more penetrating oil and my channel locks...still won't budge. The thing is pretty well mangled at this point. I've resigned myself trying to get by with the rough starting until the head can be pulled this summer...unless someone has a very good idea.
I don't need this on my day off!

engatwork · #2 12-21-2002, 07:44 PM

Seeing as how the glow plug is history and the next step is pulling the head I would remove the fuel injection lines and put the biggest pair of vise grips, tightened down as tight as they will go and try turning it with that. You don't have alot to lose at this point.

Gilly · #3 12-21-2002, 08:42 PM

You could also experiment with other tools. You could try the same socket and an extension and try tapping it on the hex, or if it seems loose you could try tapping on an 11mm 6 or 12 point.
Another possiblity is an external Torx socket may also work on a mangled hex form like this. I know it has worked for me "in reverse" as I have gotten mangled Allen sockets removed before using a Tork socket, such as on the central fan bolt on a 103 engine fan. I'd try that route before considering pulling the head. You could also try the above mentioned procedures coupled with taking it to a shop and having them either heat up the glow plug with a torch and/or giving it a few blows with an air hammer with a flat face tip.

Gilly

kweimer · #4 12-21-2002, 09:19 PM

I have been able to remove rounded off nuts, temp sensors, etc with a small pipe wrench.

dsmess · #5 12-21-2002, 10:26 PM

Thanks for the suggestions. If I put too much clamping pressure on the plug, I'm afraid I'll collapse it...it is hollow except for the stud and plastic collar.

Looking at the cut-away of the glow plug on the box it came in, it looks like the threaded collar and stud could be pulled out and an EZout or bolt extractor inserted...hopefully the hole would be the right size. I'd have a hard time getting a drill in there.

Maybe tomorrow..

Ken300D · #6 12-21-2002, 11:05 PM

Penetrating oil seems to work best for me overnight. It continues to penetrate over a long period of time. Remember to use anti-sieze on the new ones.........

Ken300D

P.E.Haiges · #7 12-22-2002, 12:55 AM

As Gilly says, heating is the best solution. If you have a cast iron head you won't hurt it. If you have an alumionum head you have to be more careful. Heat the GP red hot and it screw out ASAP before it cools.

P E H

jcd · #8 12-22-2002, 07:38 AM

Unless it is too boogered up, try "draping" a paper towel over the glowplug using a wrench/socket as per normal.

The paper towel, for me, helps take up some of the slack and gives you a firmer slip free grip.

PS, when I did my glowplugs, I put some penetrating oil on each one, every day for about a week prior to doing the job. Given the fact that just about every bolt, etc that I try to remove from this car has never been budged......ever,,,,, I use penetrating oil and time to help free things up.

Good luck,

JCD

Pete Burton · #9 12-23-2002, 01:15 PM

penetrating oil (I swear by silikroil) and heat ... but getting the plug COOLER relative to the head may work better. Run the engine to operating temperature so everything is about 80 deg C and apply ice, or a CO2 fire extinguisher blast or an spray can of electronics cleaner to shrink the threads of the plug (NOT A HORRIBLY MESSY HALON EXTINGUISHER)

CJ · #10 12-23-2002, 05:01 PM

Try a Snap-on socket. Snap-on sockets are made with a special design called the Flank-Drive. I have seen them grip rounded nuts & bolts like a champ!!!

dsmess · #11 12-24-2002, 12:31 AM

Thanks for all of the good advice. I tried a 11mm 12pt...seemed to fit snugly, but slipped when torque was applied. Then got a 6pt 11mm with the same result. A small vice grip slips right off. The small electrical stud came out in that process. Now I have a 6mm hole, which I think will receive a bolt extractor when enlarged slightly. The trouble is the injection pump is in the way to drill. I don't have an indoor place to work at the moment. My garage is full of other projects ( An Alfa, Italian bikes, and other practical items). I think I'm going to wait until the summer...I want to time the IP anyway. She started ok this morning at 32 degrees. 25 is about the coldest it gets in these Calif foothills, so as long as the other GPs keep working I should be ok. Tomorrow, it's repack the wheel bearings, then head for LA Christmas day.

240 Ed · #12 12-24-2002, 12:47 AM

...other practical items...?

Italian cars and bikes?

Gotta love it!

oldsouth · #13 12-24-2002, 12:57 AM

If you have a Napa store nearby, go by there and tell them your problem. I bought some tool there before and I can't remember what the name was but it is something you drive on and use it only once. The outside is shaped so that you can put a socket on it. It tightens as you turn it out.

Fredmburgess · #14 02-07-2003, 01:23 AM

Hey dsmess, still have that stuck glow plug in there?

Just so you don't think you're the only one, I just now got got the carcass of my #5 glow plug (300Dt) out. What a royal pain that was! Scenario went about as yours did. Wrench, vicegrips, collapsed the body of the stupid thing. Then managed to twist most of what protruded from the head right off...

Since I figured the head was coming off I just kept at it. Pulled the oil filter housing, drilled the sucker out, pulled the injector, got the piston to TDC, and used a screw driver to push the glow plug tip back out through the body of the glow plug.

That left me with a perfect hole to use an easy-out. After it sat all night with a good shot of liquid wrench the thing turned right out. What a relief! Of course, now I've got to put everything else back together - but it beats pulling the head.

Good luck. Just go slow and be careful if you drill. I got lucky!

jcyuhn · #15 02-07-2003, 11:08 AM

There's also a category of tool out there known as a bolt extractor. I'm not quite sure how to describe it - basically a socket, but with kind of a curved spline inside which grips the rounded fastener. The more torque is applied, the harder it grips. Here's a URL - http://www.sears.com/sr/product/summary/productsummary.jsp?BV_SessionID=@@@@1977930106.1044633945@@@@&BV_EngineID=ccieadchhiildfgcehgcemgdffmdflg.0&vertical=SEARS&pid=00952160000&sid=I0008300030000100085 I used these to remove a GP which rounded off. When I finally got it out, the head was completely round, but these suckers applied enough torque to turn it. BTW, it was so tight that once it was completely unthreaded, I couldn't even budge it - had to soak it in penetrating oil for 24 hours and then had a heckuva time working it out with vice grips.

One more tool for the arsenal.

- Jim