C280 spark plug screw thing
 

Having decided to change spark plugs and finally deciding they must be under that panel thing on top of the engine, I'm now confronted with a new problem. The little screws that hold on those wire connectors on three of the plugs have been stripped. I was able to get one out, but the other two seem hopeless stuck. Do I have to drill them out and if so, what are the little screw things called so I can get new ones? Are they really necessary or can I drill them out and replace them with generic screws just to hold the connector in place?

I have been able to remove stripped screws by leverage applied to the screw/bolt head and then using the correct tool to back out the fastener. The leverage comes from a tool with a fairly sharp edge that is wedged underneath the fastener's head then use the correct tool to remove the fastener. Tools to consider are gasket scrapers, wood chisels, screwdrivers, a knife (obviously one in less than good condition or an inexpensive one - I have only used a knife one time when stranded on the road and desperate), etc. (you may need to be imaginative depending on the extent of your tool collection). The leverage method does not work in all cases, but has worked often for me as a professional technician/mechanic.

Or, you can try a pair of pliers on the head and pull up at the same time you loosen the screw/bolt.

I own a 300D and not familiar with the fastener on your 280 - so I cannot give specific info about your engine. Perhaps another member has experience with your problem (for example does this fastener have a backing nut?).

Hope this helps.

Tom

Obviously the plugs were replaced before with the wrong type plug. The correct plug does not have the "screw on thing" that you mentioned. If you can't get the connector out without damaging the plug wire I would just replace the wire or wire end itself.

Clarification
 

I can see that I did not make myself clear. On my 95 C280 on three of the six spark plugs the wires go into some kind of electrical block that sits directly over the connector. The spark plug wires go into this block and the connetor is attached to the block instead of attaching directly to the plug. The other three wires go directly to their plug and they come out easily with a spark plug socket, no problem. On the three plugs that are in question the connector is attached to this block and the block in turn is attached to the engine with a very small, brass I think, slotted screw that is recessed and therefore impossible to grasp with any kind of pliers. Apparently when the previous owner changed the plugs or tried to, the slotted screw stripped and is now holding the block to the engine thus denying access to the plugs. I need to get the screws out somehow.
Maybe if someone out there has a similar setup they could add to this post and perhaps give a better description than I have.
To complicate things even more the screws aren't simple screws but part of an assembly that doesn't appear to have any real purpose beyond holding the block to the engine, but what do I know?
If I'm still not making it clear what the problem is I've noticed that some folks send pictures. I'll borrow a digital camera and see if I can get a decent picture to put on line. Owning a Mercedes is certainly expanding my horizons.

On my E320 the block just slides down onto the plug and those "screws" do not really hold anything down. The block has a hole that fits down over/around these so-called screws. You should be able to just pull the block straight up/out. Post a pic if you can. I think you are seeing an attanchment there that ain't really holding anything. I have always assumed the "screws" to just be some kind of guide pin.

Drilled them out
 

Thanks for the input everybody. I grew impatient and decided to forge ahead. I drilled out the stuborn screws (they really were screws in addition to a guide stub), got the blocks off, changed the plugs, and then went to Napa and got three replacement screws (75 cents). I put them in place of the ruined ones, buttoned it up and lo and behold it fired right up and purred like a kitten. It took me 5 hours to change my plugs, but I'm gaining more confidence every day that I don't have to be entirely at the mercy of the dealership. Thanks, Bob H

The screws that you are talking about are only studs. They don't have a head. However, some are stubborn and the coil feels like it's screwed down tightly on the valve cover.

Vinamg

is this a 104 engine too? the 5 mm allen screws are what hold those in place through the cover...

We are not talking about the allen bolts that hold the cover, but the small studs that guide the 3 coils in place.

Vinamg

Yes, my engine is a 104. And I did use a five mm allen to get the cover off. And the allen bolts did go through the holes provided on the blocks and into the engine block. Well, now I really feel insecure. If what you guys are saying is true then I really didn't need to drill out these "screws"? Yet I feel in my heart that these blocks were firmly held to the engine with these little screws and I now have the remnants of them sitting on my work bench. And there are threaded holes in the engine block to recieve the screws. Like I mentioned, I replaced them with generic screws and they screwed into the engine block nice as can be. I'm truly not sure what to think at this point. Is it possible that there is a different configuration within the 104 engine? I believe I read somewhere in all the booklets that the manufacturing date on mine was November, 1994 if that could make a difference. Bob H

the reason i posted about the allen screw was because i read your post just before i did mine for the first time. i pulled the blocks off and saw those brass screws and wondered if those were the ones you were talking about. the screws do not have heads and are recessed in the hole so they can't hold the blocks down unless they are stuck. if your scews had heads then someone may have replaced them. i looked at the cover and saw the protuberances underneath that push the blocks down and saw that the allen screws go through two of the holes in the block. so my conclusion is that they are what hold the blocks down. lucky for me my blocks just slid off. you had to do what you had to do. it's important though that the facts get stated because people do use the threads as a reference (like me).

cheers

Sadder but wiser
 

Thanks for your input. It sounds as if you have the same configuration as mine. I guess I need to face the very real probability that I didn't need to drill them out - that maybe a little more aggressive pulling on those blocks would have done the trick. We'll have to see if my curiousity about the situation will overcome my inclination to leave well enough alone and move on - sadder but wiser. In any case the car is running very well now and it would seem that this story does have a happy ending. I really appriciate your opinions, and I look forward to picking your brain on other problems. Bob H