617 Glow Plug Stuck! - PeachParts Mercedes-Benz Forum

project84300sd · #1 07-24-2009, 07:16 PM

Started to change out my glow plugs last night (prevous owner had used Champion Glow Plugs). I was able to very easily remove the old glow plugs from the first 4 cylinders and replace them with Bosch Glow plugs but the last glow plug just won't budge! Ive been consistently soaking the area's around the glowplugs with PB blaster for a few days.

I ended up rounding off the glowplug on the #5 cylinder (right next to the oil filter housing). Ive tried a special bolt-grip rounded bolt remover socket, a pipe wrench, vise grips and even applied heat to the glow plug (bad idea since the area was soaked in PB blaster). Nothing works and now Ive mangled the glowplug. It just will not move!!

Any ideas on what to do next? I am at the point where I am just going to put it back together and take it to an indy.. but figured its worth a shot asking on the forum since money is very tight..

kerry · #2 07-24-2009, 08:05 PM

Have you tried tightening it as opposed to loosening it to break it free?

the tenor man · #3 07-24-2009, 08:23 PM

I believe the head on the 617 is cast iron, so I don't believe heating will do any damage.

I would heat it again and try to grab in with a pipe wrench or the equivalent. Hopefully, you still have something to grab.

You may have to remove the oil filter housing to get some more room to work.

As a last resort...carefully drilling out the old plug and using an easy-out tool.

My opinion is that more heat is the answer...It went in...it'll come out!

Good Luck!

The Tenor Man

Diesel911 · #4 07-24-2009, 09:55 PM

I am suposing that what was done at this site would work on yours too. However your Glow Plugs are shorter than the ones in this article.

http://alan.mcreynolds.googlepages.com/howtoremovebrokenglowplugs-mercedesom606

If you take it to an Indy and he cannot get it out he as the choice of Drilling It Out Himself And Possibly Messing Up Your Head. He would have to take responsibility for that.

Or He could play it safe and at the same time make more money by removing the whole Cylinder Head and sending it to a Machine Shop for them to Drill it Out.

If you were in business which would you do?

You could also pull out the Injector on that Cylinder and spray some PB Blaster on the Electrode end protruding into the combustion Chamber to soften the Carbon.
You also might be able to see if the tip of the Glow Plug is swollen.

If there is something sticking out maybe you could slide a nut over the end and Weld it to the Glow Plug. That would also supply some serious heat.
I would not worry about heat and PB Blaster. Some Heat helps wick it in between the parts.

pawoSD · #5 07-24-2009, 10:01 PM

I would apply lots of heat to it then grab it as tight as you possibly can with good vice grips (that still have good teeth on the tip)....then go at it....this has been successful for me numerous times in that situation.

Diesel911 · #6 07-25-2009, 01:55 PM

A Pipe Wrench will also grip well. However the concern is shearing it off.

pawoSD · #7 07-25-2009, 02:47 PM

Seems strange that it could get stuck since its an iron block....even the original plugs that I removed on the 300D in my sig weren't that hard to get out....and they had been in there for 25+ years.

Dionysius · #8 07-25-2009, 02:48 PM

How about this since nobody brought it up?

Install the four good plugs. Start it and apply heat by taking it on a long trip ending with uphill climbs. You could also even block some of the air going into the radiator. Get the temp gauge up to near the red zone. This will get real heat into the head and all the thread run.

Diesel911 · #9 07-25-2009, 04:04 PM

The origional poster said he rounded of the GP hex. This makes me think that Carbon has some how gotton past the sealing area and up around the body of Glow Plug. Ounce it sets up Carbon can be very hard to deal with.
I say the above because the OP did not say the GP turned at all.

Sbean · #10 07-25-2009, 05:10 PM

Applying heat to the GP will cause it to expand. What you want to expand is the iron around the hole, without heating the plug. So try to heat the iron first, and fast; then try turning the plug. Steve

Diesel911 · #11 07-25-2009, 07:19 PM

Quote:

Originally Posted by Sbean

Applying heat to the GP will cause it to expand. What you want to expand is the iron around the hole, without heating the plug. So try to heat the iron first, and fast; then try turning the plug. Steve

While heating the Glow Plug will expand it; heating it will disturb how it is seated in the head.

While it goes against logic in the case of bolts and such this tends to help loosen them and allow Penetrating Oil to wick into the threaded area.
Illogical as it is I have seen it work before.

As you said heating the Head only will tend to enlarge the hole that the Glow Plug is in.

Combination: Heat the Glow Plug up good so it is expanded and pushing against the head. As it is cooling spray on the Penetrating Oil to get it to wick in between the threads.

Let every thing cool while in between spraying with more Oil.
When it is cooled Heat only the Head if you can.

When it is good and hot try removing the Glow Plug.

I have also seen where using a punch and Hammer giving the Head of a bolt several good but non-damaging raps on the head have helped to loosen it. Again you are disturbing the seating in the threaded area by doing this.

connerm · #12 07-26-2009, 04:50 PM

and use good 6 point sockets.