Spark plug replacement on E320
 

This is a V6 engine, and has 2 plugs per cylidner. However they are positioned so that they face the sides of the engine bay with very little space to use any tools to remove them.

How do I go about doing this? Any help appreciated.

You can use a 5/8 or a 17mm wrench to remove the boots. I used a 5/8 but a 17mm will give you a little more room to work with. Just put the head of the wrench behind the boot and apply pressure against the engine block. Presto! They sell 17mm wrenches that have a curve to it which makes pulling the boot easier. I saw it on ebay..

If you remove the coil packs first you will gain alittle more room to work. With the use of a spark plug socket and a socket wrench it is possible. I believe I removed the air cleaner box as well to gain a little bit more room.

I used a spanner to remove the boot of the first spark plug. Then I removed the plug and it looked OK, not oily or corroded. Even though it was the "easiest" one to access, it still put up a lot of resistance (removing the boot). I tried number 2 but it was impossible, there was no good purchase on the boot to pull it safely out and I did not want to push it laterally with the spanner. Removing the other four which are behind the first two is impossible because the bulkhead is too near the engine block and there is not enough room there. There are things on the way and I did have the ait filter cover off but it did not help much. The other side of the engine is even harder.

Try twisting the boot first to loosen it up. If you get the boot off use dielectric greese to help prevent it from seizing to the plug for the next time. I struggled with my E320 the first time, it took me 1.5 hours to replace the plugs.

well that will be a job for next weekend. although the one sample plug I pulled out did not look that bad, a good brush and it'd be like new.

on a related issue, when you do the oil change, do you drain it underneath or do you use a pump? I used a pump but am not sure if I managed to drain it fully this way. next time I will remove the sump plug.

That question will turn this thread into a flamer.

I prefer to drain the oil hot and from the bottom (gravity) so that I can get a good look around to see if there are any potentional problems (fluid leaks, torn boots, etc.)

My belief is that if you catch a problem early on it is less costly to fix then a problem that causes the car to become undriveable.

I took a cover off and looked at what looked like the sump plug, a small bolt with a leather washer looking brand new. I do not believe the car has ever been drained from there, there are no oil smudges to be seen, it looks 100% new. So since I was not sure if that was indeed the oil drain plug I did not touch it (it could be the auto-gearbox drain or final drive drain or god knows what).