spark plug broken
 

1986 mercedes 300e
I have broken the spark plug off leaving the thread body of the plug in the cylinder.
I have had these plugs out many a time but since the shop put new leads on the plugs are extremely tight.
Any suggestions on how to get the rest of the plug out?
Thanks.

Take it to the shop.

They put it in too tight, let them get it out.

Tom W

Thanks Tom.
Problem is they claim they never removed the plugs. My reply was if they were troublshooting the ignition and servicing the engine why didn't they check the plugs???

Can't wait to hear how this turns out....Good Luck!

Easy out
 

I snapped a spark plug in my 88 300zx a few years back. After my heart started beating again, I called a mechanic buddy and he said to get an easy out and stick the 3/8" square drive end into a suitable socket (electrical tape helped to ensure a snug fit. Attach a socket extension. Then, tap the "chiseled" end into the remains of the broken spark plug until it bites, then slowly and careful use a breaker bar or rachet to break it loose. It worked like a charm!!! After that fiasco, I used dialectric grease every time I repaced plugs. Good luck!

p.s. I believe the easy out size I used was a 6t-4

EZ out size may vary by manf. I use a #9. Get the innards out of the broken off plug before using an ez out.

Just wondering if it be better to remove with engine cold or hot? Would spraying wd40 help?

Rule of thumb on an aluminum head is to change plugs when cold.
After you get the threaded portion out, crank the engine over a few times, to blow out any debris that may fall into the cylinder. ;)

There may be a valid reason for installing plugs in a cold engine, I think removing them from a warm or hot engine is easier. Certainly a dealer ship tech is not going to wait for an engine to cool.

Wow. Thanks for all the input. I have sourced out the ez out tools and will be applying all the suggestions this afternoon.
Let you know what I learn today.

Good luck. Take care that you locate and account for the side electrode(s) that may snap off and drop into the cylinder. A piece of wire with a blob of grease on the end works well for fishing them and other swarf out of the cylinder.

PSark Plugs
 

:eek:NEVER NEVER EVER REMOVE ON A HOT ENGINE. :eek:

You most likely have an aluminium head which expandes with heat and will vise up on the plug. If you think a broken plug is bad try bringing the plug out only to find that it brought the head threads with it. You should never remove any bolt from a hot aluminum block or head. It be very bad.:eek:

While I'm thinking about it.
 

Apply some petroleum jelly to the surface of the spark plug you are going to drill and tap out. The PJ will catch the small shavings and keep them from falling into the cylinder when you back the plug out. Drill the hole slow and it will keep the chips bigger and easier to clean out. Also make sure that you don't drill completely throught the plug as it will blow out the back end and all that stuff falls into the cylinder and is near impossible to get out unless you crack open the head to get in there. EZ outs are great but be carefull you don't go frying pan to the fire.

The hole for the spark increases in size when hot. I have no idea where you got the information it decreases, but it's wrong.

No need to drill a broken spark plug- I never have.