LCMilstein

I once again fall upon the mercy of my fellow Rennlisters. If you've followed any of my posts, you'll see that I try to do my homework. You'll also note that while I know more than others, I know less than just about anyone on this list about the nuts and bolts of the cars. I am attempting to check out the spark plugs on my 1987 928 S4, and I'm in need of some advice.

I've purchased the right tools (and have some that came with the car); I've read Jim's PET; I've searched this forum; and I've watched several how-to videos on the web about spark plugs in general.

The PET has a walk-through on removing the plugs, but unless it is missing MANY steps, I don't know how I'd have access to them.

Here's what I've done so far:

1. Removed the Air Intake Hoses on top of the engine compartment;
2. Unstrapped and removed the upper Airbox housing and the air filter;
3. Removed the Injector covers; and
4. Looked all around

Problem is, I've never done this before, and though i know what a naked spark plug look like (now), I don't know how to identify where they are when they are installed.

Based on generic videos and looking at the spark plug wiring sets for sale on the big 3, I *think* the plugs run 4 on each side of the engine, in parallel, below, and towards the center line a bit, from where the injector covers sat. Does that sound right? To access that area, I would have to remove a metal bar and some wiring running along it, which isn't mentioned anywhere in the PET. Is this right? Should I post pictures? Would anyone in the process of replacing their plugs on a 32V engine be so kind as to post a pic so I can be sure I'm pulling the right thing?

Please PM me with abuse and leave the thread family-friendly?

Thank you.

-Lee

Big Dave

Leon Speed

Hi Lee,

No need to pull the injector covers. The spark plugs are in the center line of both left and right cam covers. To reach them, you need to pull out the spark plug covers, they are connected to the large guage (black) wires.

Dean_Fuller

What might be throwing you is the plugs are recessed ( way in there ) and you really can't see them to identify them. Follow the plug wires. Pull them one by one. You will need an extension to reach them. A plug socket is required. ( socket with rubber inside to grab the plug when its loose. )

hacker-pschorr

With the 32 valve cars I find it much easier to have a swivel spark plug socket (all one piece, not a swivel on a regular socket) connected to a locking extension.

I picked up one of these sockets along with three different length locking extensions for less than $25 at a hardware store.
The locking extensions are necessary since the rubber plug holder in the socket will some times pull the socket off the extension.
.

Garth S

Now that you know where the plugs hide, the next step is to pull the connectors off: sometimes, they are difficult to release .... so take a narrow flat blade screwdriver and a drop of lube, and slide it carefully between the valve cover hole and the ribbed rubber seal of the connector. It acts as if a vacuum were broken, making their removal easier and far less a PITA.

BTW, once plugs are replaced, a worthwhile improvement is to remove the two distributor caps and very carefully scrape any crust and corrosion ( arcing deposition) from the brass posts: take care to not scratch the glass like interior finish. This is a quickie tune-up that often has better results than new plugs.

Stromius

Try the original spark plug tool if it's still in the tool kit...works great except for #4 is a bear around the cross bar

the flyin' scotsman

As stated above the spark plugs a very recessed; I use a spark plug socket with a 6" wobbly extension which provides angle for all 8 cylinders.

LCMilstein

Thank you all. I now see exactly where they are. I haven't been able to remove the connectors, but I'll try the suggestion from Garth on Friday and give it a whirl.

Mrmerlin

if your having difficulty removing the spark plug wires try using a 5 or 6mm allen wrench.
This seems to fit well underneather the wire and the socket and gently pry up this will lift the spark plug socket without damaging the wire.
After you remove the wire place it aside and look into the sparkplug wells any that are filled with oil indicate the cam cover seals are inop. so a reseal is indicated.
If the wells are dry then using compressed air to blow into each hole. this removes any dirt, if there is oil in the hole use the compressed air with a rag over the hole so it doesnt spray oil all over your fender.
Use some anti seize on the new spark plugs. Also remove both of the coil to cap wires and make sure they look dry and non corroded, and check that each coil has a ground wire attached to its mounting bolt to the cylinder head

Nightfly

Car is running alright, but after 70K miles I want to change my plugs as well just as routine maintainence.. Who makes the spark plug socket with the u joint on it that will stay on the extension? I have a snap on dealer only a couple miles away if it's them, and a MAC tools guy stops across the street at the body shop every week.

LCMilstein

Just an update. After this thread, I was able to remove the plugs. I confirmed they were Bosch Platinum plugs, so in the interest of trying to pass inspection, I decided to down-grade to the Copper variety. After assuring myself I could do it without help, I took Luan up on his offer to help me through it and we performed the surgery this past weekend.

In so doing, we learned several plugs had been loosely installed previously. The new plugs, torqued down to 21 make the car feel entirely different. It starts more reliably, it idles better. I'm really happy.

Now, if I can pass smog, I'll start in on replacing gaskets, hoses, and such, and making it a bit cleaner under there.

3 things to take away for any neophytes like me out there:
1) Get the spark plug wire removal tool from Sears or Pepboys, etc. Pulling with a non-damaging vice was MUCH easier than doing it with my fingers;
2) Rennlisters are fantastic resources; thank you all; and
3) My experience with AJ USA in San Diego leads me to NOT recommend them.

928Collector

On earlier 16v 928s can anyone help with how to pull the two plugs closest to the windshield?

Mrmerlin

remove the air cleaner assembly then you can reach the plugs

928Collector

Thank you.