stuck spark plug
 

What is the best way to remove frozen plugs on m103.Can i soak it with wd40 overnight.Any ideas?

I had this problem on a 500SEL that had platinum plugs in it for 100k miles. I wasn't very lucky and the last one I was changing broke off.

Try using a torch and heat the plug and let cool. Try this a few times also spraying rust penetrent in between.

The heating up, and cooling causes the metal to expand and contract and will hopefully break the joint.

Be patience, its no fun when one breaks off, go slow and work it back and forth. Sometimes you can try tightening a little first.

Good luck

Tox!

AHhhhh ! I had this happen to a GTI that I worked on. It broke off. Can anyone say "heli-coil". What a major pain in the arse. What about using anti-seize on them? Any thoughts? Ideas?

The WD might help, and can't hurt.

If they have not already broken off, then you may want to try some 'percussive' force. Carefully tap the wrench with a hammer.
As Tox said, alternating with some tapping in the tightening direction can help too. Use minimal socket extensions. Rotational force is your goal, as lateral force can shear the plug off. A pneumatic wrench would be ideal...

Once you do get them out, I have had excellent results with anti-seize. After 30K miles they come right out, and despite the heat, some residual remains on the threads.
I have since decided that the aluminum particals in any excess anti-seize paste that melts away may not belong in my engine. Perhaps not really a problem, but why chance it.

I have now switched to using a heavy molybdenum grease, which has a much higher temperature resistance (more grease remains on the threads after 30K). Molybdenum grease is typically marketed as "assembly grease" for engine rebuilding, or as "brake grease" for sliding surfaces on brake components.
This stuff really holds up well, and the plugs go in and come out easily every time.

One of my friends swears by silicone grease for this purpose, but I have not tried it. It just seems too thin to stay put for the long haul, but the temp rating is high enough, and I have an open mind about it...

See this thread for Steve Brotherton's take on anti-seize on spark plugs.

http://www.peachparts.com/shopforum/tech-help/7964-560sel-distributor-cap-rotor-plugs.html?highlight=antiseize

I have not observed any problems with anti-seize becoming baked on. Some of it is certainly burned away (some of the threads actually protrude into the combustion chamber, and I doubt any grease can survive that!)

Nothing persuades a spark plug to come out like a 3/8" impact wrench. I use a lower powered model that delivers lots of blows but very little force so the plug doesnt break. It usually only takes 4-5 seconds before it comes right out. I always run a chaser down the threads to remove any rust residue and clean up everything before replacing the plugs.

Removing Spark Plugs
 

The two main causes for stuck spark plugs are cross treading and over tightening. It is very easy to over tighten the plugs if you don't use a torque wrench.

I have found that a light coating of anti-seize helps a lot also.

Hi Ronald
Before you use torches and air guns,I would recommend to drive your engine very hot.I dont mean overheating it ,but going on the interstate and driving in the lowest gear possible(like55-65mph in 3rd gear)for maybe 10 minutes or so,Get back to your house/garage,still driving with high high rpm and put a proper spark plug wrench
on the bad boy.That might even work on a cross threaded plug ,it always worked for me on seized plugs.When you put new plugs in ,do so on a cool engine and with High Temp anti seize lube.
Hope this helps.
AndyM86

Andy,
Welcome to Mercedesshop I will try you technique ,What part of jersey are you?

Hi Ronald
I'm in Morris County.Where are you?
Let me know how you make out with that spark plug.
AndyM