ihaveaquestion

Was working to replace the spark plugs on my 2008 C300 Sport this morning. The screws on the ignition coil were very difficult to remove (don't think the previous owner ever bother to replace the spark plugs) and they are made of somewhat soft metal which is very prone to stripping. Anyway, long story short, I've stripped one of them and another one is not looking good either. Could someone please advise on a plausible solution to remove the stripped screw(s)?

A supposed easy job is now turning into a mess.

But even with just two out of 6 replaced, I can feel the engine feels peppier....which is encouraging.

ItalianJoe1

You rounded the head of the screw off? Use a socket for stripped bolts, they have a twisted design inside that cuts in deeper as you try to loosen the bolt so they grip. Will not be able to re-use those bolts but they will come out that way.

You are using the proper size tool on the coil bolts right?

ihaveaquestion

It's a screw not a bolt. It's is proper size tool but the soft metal does not give confidence when I try to loosen the screw.

ItalianJoe1

They are t30 right? You can use a chisel to turn them loose if you know how if they strip, once they are broken loose they should come right out.

ihaveaquestion

Thanks. I got it resolved. What I did is that I bought better T30 driver and applied tons of downward force and quick, impact turn to loosen up the screw. No way I am putting the same screws back in so I am letting two of ignition coils held down by one screw only currently.

Anyone know the correct size for the screw? The width and length? I look up a couple of parts site they don't list it out.

JohnnyC

most likely M6.

bbirdwell

Part number for the single bolt used to attach the coils on the E-class is A 001-990-72-12. You phrased it in such a way that it sounds as though you have two bolts per coil.

eeuroparts carries the bolts for $1.49 each.
Ebay has them for 99 cents each.

Do a search on Mercedes coil pack screw size.

ihaveaquestion

This?

https://www.ebay.com/itm/1998-2003-M...S!-1:rk:3:pf:1

Hmmm, doesn't look like it. The thread itself may be a fit but the head looks different. Mine is wider and flatter.

C300Sport

Just so we are clear; it is a bolt. As long as the head seats properly, it doesn't really matter what it looks like. Did you use anti-seize when reinstalling?

ihaveaquestion