1995 S 320 Spark plug replacement
 

Trying to get some info. on inspecting, removing & replaceing plugs, wires & coils.

I guess you could inspect the plugs, but if I was going to that trouble I would surely just replace the plugs. I do mine every 30,000 miles. Be sure to get the proper non-resistor type plug. Bosch F8 DC4's. Many threads on this topic. Do not use the platinum plugs. Remember to use compressed air or a computer canned air to blow any crud out before you remove the spark plug(s).

A known issue are the rubber connectors, 3 of them. They deteriorate over the years due to the heat. I just replaced them on my '97 S320. I don't think visually inspecting the coils is useful. You can find them on line.

Steve

If your car has the original wiring harness you may run into a problem. Changing the plugs requires disturbing the harness which will probably ruin it - if it's the original. If it's not original you should be fine.

Hi, bumping an old thread here - I searched :) 1995 S320.

I'm lost - where are the spark plugs? I opened up the cam cover, and now what? There are some brass flat-head screws holding the gray thingies attached to the black wires (one in each, with some sort of nickel looking nubby in the other) - I can pull those wire plugs out from each grey thingy, too. I tried to unscrew one, but it started to distort so I left them alone...

Picture attached.

Thanks for your time and help!

Pull them straight up, and the red thingys. Remember where they go. Replace the 'sticks' under the ignition coil. Big thingys...

Thanks for the response, and I'm sorry about my vocabulary - trying to learn. No idea what the red and gray things are, but seems like the gray thing is called the ignition coil...

I tried pulling straight up, but I think that single brass screw was preventing it from coming up (feels loose on three parts).

Is the assumption to remove the brass screw before pulling up on the gray thing correct? I tried, but it's lodged in there pretty good and I'm concerned about forcing it as the brass appears soft. Circled in red. There's only one for each of the three.

How do you get the red thingy out? Do I turn it, or it just pulls up?

On mine, the screws were inconsequential. More of a position guide... The ignition coils were only slotted into it...

Okay, I got it - yesterday the car was hot (working in the sun) so everything was expanded. Just tried it, and everything pulled out nicely. What I thought was a screw was just a guide, doesn't hold anything in. Wish I tried that this morning before ordering the all data subsscription, it is not very helpful at all.

Now to go see if the parts stores have the f8dc4's or ngks without resistors. Fastlane sent me the boschs with the resistors, oh booger.

Oh no.. how do you get to #6? Do I need some shorter extensions and flexible or "u joint" type thing? Or do I have to take apart everything above it? Hrrrm.

2 short extensions and a u joint work quite well... Don't overtighten the plugs....

Ah, got it, thanks :) A single short extension, u joint, and the spark plug socket worked for me :D Just waiting for the f8dc4's to arrive. Then I'm all set.

Thanks so much again for the help!

All plugs replaced, car didn't blow up when I started it, woo!

One last question: of the six allen screws that hold the cover down over the spark plug stuff, I can only get two to tighten. The others just twist and don't hold anything down. I recall they were tight when I first started this project. Is that normal?

It's likely that the female threads in the head are stripped, probably due to a service tech using an air-powered tool and overtightening.

Yup, just confirmed it, I took off the cover and pulled the coil packs, and the allen screws get a very light tight if I push down slightly directly into the head. Bummer.

Is there a problem with just leaving the cover on with the screws in place, not tight? Searching the internet showed to fix I'd have to either replace the head or get one of those stripped thread repair kits. Hmmm.

might try JB weld in the holes and waxing the screws so you can get them out again..... Doing that to remake the threads.... I'm not sure if this works, so, I assume no responsibility....