RevAgent

I bought my '85 back in May with 86XXX miles on it; good overall condition for the year - it was a steal. It has a miss but starts rite up; idles a little rough, but no leaks, etc. The PO informed me that he had it at a mechanic and it needed a new set of plug wires, and basically a good tune up. Not a problem, rite?

So I got a new set of wires from Roger, as well as new Bosch plugs, coils, and distributors. I finally got around to replacing all these parts today. I started with the wires and plugs. I got the first three done on the driver's side bank, and noticed that the plugs [definitely the originals] had a lot of oil on them, especially on the threads. I am new to 928's and heard about them burning oil so I figured it was somewhat normal....

I got to the last plug on the driver's side bank, the one closest to the firewall, and when I pulled the plug connector free, oil came pouring out of the connector!...I proceeded to try and remove the plug and it's really in there, and the plug cavity is filled with oil as well...Now it doesn't take a Porsche Tech to realize that this is not good. At all. There is some oil inside the side plenum that was removed to access the plugs. There is no condensation coming from the exhaust so I'm thinking it's not a head gasket...

I have since stopped doing any work on the car, and am fearing the worst. Someone please tell me something that will put my fears to rest...

Gtaebr

First relax.....

Could it be someone had a go at that plug before and could not get it out an poured oil in there to help ease it?

Suggestion.... Get some rag/towel and get that oil out so when plug comes out it don't go down hole.

Then get the plug out and take a look at plug report back.

It's gonna be ok.... There is all the help you need here on the forum.

RevAgent

Thanks, Joe. It is possible that someone tried doing that - I have seen stranger things...I will get that other plug out later today hopefully and report back...very nice looking car by the way - love that color!

Gtaebr

Thanks!
Now let's git er done and firing on all 8!

Tom. M

If the sparkplug hole cam cover seal is cracked or even missing it can allow oil to collect in the sparkplug hole. You might have to pull the cam cover to see if it's still there or if its in good shape...

Giovanni

My ex 88 had the same issue. The spark plug connectors were covered with oil. I removed the cam covers and replaced the spark plug o-rings, cam cover seals and grommets. Problem solved.

I would advise you to replace the old tired seals with new ones otherwise your new wires may not last you that long.

docmirror

Have no fear. This is a fairly common issue. Also to make things even better, this oil in the plug wells was likely the cause of all the mis-firing to begin with. I know it was on my car, and I had the same problem.

Now, to fix it. You can simply take out the plug and let the oil fall into the cylinder, but there is an issue with this. If there is too much oil in the cylinder, it could hydrolock the hole and cause damage to the head, piston, rod, or gasket. The best think to do, is get a small syringe and vacuum out as much of the oil as possible. Then, remove the plug and with the plug out, spin the engine around a few times to throw the oil back up out the hole. This is very messy, but it will work. Vacuum and draining it is much better.

The cause is the O-ring seal the goes around the plug wells in the cam cover. I'm betting they are the originals, and have degraded over time. They can be replaced by removing the cam covers and using new seals on the plug well, and the cam cover. This is a fairly major job, but it can be done with the engine in the car.

Roger has the seals for this job when you are ready. It's also a good time to renew the seals on the intake, and clean up under the intake, renewing the vacuum lines, and maybe even the knock sensors.

work clean as you can, but realize that the wells will fill with oil over time. If you have that syringe made with a very narrow copper line, you can get much of the oil out of the well before pulling the plug.

Have fun, keep us informed.

Mako 928

It sounds like the very common valve cover O seal is leaking. This is the seal where the spark plugs are located in the valve cover. I had this problem for awhile and would just use a shop vac to vacuum the oil out once in awhile.
The bolts for the '85 valve cover is another issue as they are a two piece set in the head/valve cover and can break off. If this happens it can be very dificult to tap out. For '85 '86 MY pulling the engine to gain access will be the only repair due to studs being used for the heads instead of bolts.
For now I would just vacuum out the oil and keep tabs on how much oil is filling up the holes.

Mrmerlin

If you carefully clean the plug hole with a rag and some brake cleaner you should be able to see if there is a rubber seal around the cam cover where it seals to the head, if there is one then you shouldnt have too much of a problem .
That said i would continue cleaning out the well as best you can.
You could also spray some brake cleaner into the well and then put a rag over top of the hole and with a compressed air gun blow it into the hole, if you do this a few times it will remove the oil then you can fit a spark plug wrench into the hole and get the plug out, without all of the oil running into the cylinder. Wear safety glasses.
You can also leave the plug alone till you replace the cam cover gaskets and the sparkplug O ring seals.

I would finish installing the wire set and take one of the good used plug ends and spray some silicone or WD 40 into the top part where the wire goes in and then unscrew the wire from the connector and screw this one onto the wire that had all of the oil in it , keep the new plug end dry till you have fixed the leak.

RevAgent

Wow, guys - thank you all so much for the quick and detailed responses. So is replacing all of these seals and o-rings as simple as removing the cam covers, and replacing the old seals, o-rings, & grommets?

tveltman

yep, do the cam cover seal WYAIT. You're gonna have the sucker off, you might as well replace that too. Also if your valvetrain rattles significantly, it might be the right time to refurbish those oil check valves in the head (you need to get the cam covers off to do so). Good luck!

the flyin' scotsman

There can be many 'while your at its' when the valve cover is removed. I'd base when to do the work with how much you want to drive the car this season before winter arrives.

If your going to wait 'suck' the oil out of the spark plug hole and just replace all 8 spark plugs leaving the rest of the process until you've had the VC's off, seals replaced and reassembled.

Did you get disti rotors for the project?

RevAgent

Yes I did get new distributors, coils, and rotors as well. If the seals are simple enough to replace I'll just order the parts from Roger and then make a day of finishing the ignition system and replacing all the seals...I'm assuming the seals/gaskets are not all that difficult to do...are the cam cover seals rubber, or paper/composite and do they require any sealant, or do they go on dry? Are the inner o-rings and grommets the same? Thanks again, guys

docmirror

Ok, as has been said, there is an issue with taking off the bolts that hold the cam cover on. They are custom bolts and they've been on the car since 1985. That's about 25 years. In that time, they get heat cycled, and some of them will most likely be stuck.

Removing the cam covers without breaking one or more of the bolts is the exception, not the rule. Plan in advance if you can work the bolt areas in case of breakage to replace a bolt by drilling, and easy-out, then tapping and/or using a thread insert.

The cam seals are rubber, they do use a sealant in the corners. The inner o-ring/grommet for the plug hole are all the same for 1985-1995 I think. There is also a small o ring under the head of each cam bolt, and these should all be replaced as well.

Gtaebr

See no reason to worry..... As you have only had her since may and your winters are long and cold.. Enjoy her and give her a good overhaul this winter.. Assuming fuel lines timing belt etc are in good shape.
A nod to all the exellent advisory posts and posters!