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I chucked a new set of plugs in my NA8 turbo tonight and discovered the spark plug well on cylinder 4 was literally full of oil!

I have not had any running issues and never seen oil anywhere it shouldn't be around the top end...so what is happening? Is there a seal on the cam cover that is weeping there?

camshaft cover gasket

Cam cover gasket is leaking around the spark plug access. You can try to gently and evenly tighten down the cam cover, starting around the area of No 4 plug. if the bolts are already down super tight then it looks like its time for a gasket.

Cheers guys...I will see if anything can be done with it, maybe I need to pull the cover off and reseat it? Or is the gasket sacrificed when the cover is removed?

The gasket is very hard to damage its very robust, it is located into a channel in the cover, the rings around the spark plug access have tabs/lugs to keep them in place, its unlikely that the joint has moved out of place. The corners of the joint where it steps over the cam shafts require gasket (automotive silicone) compound. If your going to take the cover off, then I would have some silicone handy, you can perhaps dope up the area around the No 4 plug access if its out of shape.
If the car isnt used every day, you can have a look and decide to get a joint if need be, but find out where you are going to get it first and if they have it in stock, this is obvious I guess if you need to keep on the road.
You need to remove the coil pack to get the cover off, there is a 3rd lower bolt that is difficult to get to, in some cases you may find this bolt hasnt gone back in if someone has been at this job before.
Just something else that has come to mind, since you engine is turbo charged, hopefully your crank case is breathing OK, if your boost pressure is getting into the crank case then perhaps the joint around No 4 is the weak spot and this pressure in the crank case is forcing the oil out.

for $22.00, you might as well not muck around and just fit a new one.

Where can you buy one for $22 ?

If nothing else this is what it looks like.

http://www.ebay.com.au/itm/MX5-NA-NB-94 ... 20b946bfc3

Thanks for that. Much appreciated.

The car is a weekend only trackday car so no worries if I can not fix something same day.

I know the coil pack does not have the 3rd lower bolt....I already 'took care' of that

I did have a bit of a thought that oil is being forced in there. The CAM belt was done about a year back so I am thinking that the seal was nipped when everything went back together.

What can I do if it is a pressure issue?

Not sure of your turbo set-up, but as you probably know you cant stay with the stock crank case ventilation setup, in general the crankcase is vented to a catch can or just a filter on the right hand side outlet on the rocker cover. The vent on the left hand side outlet that goes to the intake manifold has the PV (pressure/vacuum) valve in it, this valve should close if the inlet manifold sees pressure (in boost) and open when in vacuum, if this valve has failed your boost will end up flowing into the cam cover, your catch can or filter may not cope with the added pressure. I am probably telling you how to suck eggs, but worth checking.

You are not telling me to suck eggs at all!! I was unaware that you can not use the stock ventilation...I will look in to this ASAP and see what my car has on it, the last owner had an AVO kit fitted but I should think this was not given much thought.

Regarding the catch can not liking the pressure, I assume this would be why I have seen catch cans with a small filter on the top?

You probably dont need to get too far ahead regarding the crank case pressure, as long as you can check it is venting properly. One thing that can happen on these forums is you get opinions that can lead you down the wrong track. It could simply just be that the cam cover gasket needs replaced. But since you have a turbo set up it is possible that any additional crankcase pressure from boosting would not be helping a leaky cam cover joint.
Try the obvious and easy stuff first, tighten the cam cover bolts, check your breather set up and see its ok and nothing looks out of place, blocked or wrongly installed.
Then go for the cam cover gasket itself, if its a weekend track car you can easily do an inspection of the cover joint and then chase a new one if required, the joint may look ok but have simply gone hard with age.
The catch can set up can vent to atmosphere via a filter as you said, or can be vented back to the turbo intake depending on your turbo set up, if you are still using the MAF in the air intake you cant vent into the turbo inlet. It gets complicated and loads of comment has been written about this topic.

deviant wrote:The CAM belt was done about a year back so I am thinking that the seal was nipped when everything went back together.

There is your issue. If it wasn't replaced when the cam belt was done, then you'll have oil leakage issues as they never go back on the same. Surprized it wasn't replaced when doing the cam belt.