Most cars use a design with overhead cams and a valve cover for service. Over time, the gasket that seals the valve cover to the head wears and eventually fails. Typically you will see leaking oil - but sometimes the leak occurs in the spark plug wells.

This is a '93 Saturn SW2 - maintained not so well.

Features:

Cracked Windshield
Purge Solenoid Damaged (stuck closed)
I suspect the valve guides are worn... I have good compression, but she eats oil (not enough to smoke though)
Automatic with classic reverse hesitation (common for this tranny)
Rear Passenger window not working - stuck slightly open
Traction control (with an overide button in the cab :P)
Oil service interval -- wayyy too long (which forced me to replace the timing chain and guides)
Odometer stopped years ago at 68K miles

My parents owned this car - and I kept her running. Normally, the T-chain lasts forever. Unless you let the oil level get low, in which the guides literally explode. It was driven without an upper guide (and only partial side guide) for several thousand miles - which nearly ate a hole in the valve cover.

I do commend the design... Even with everything going wrong... she just refused to die. All of that oil in there, and she kept on running. Even with the T-chain rattling away inside (slowly eating the VC) - she kept on running. I was sad to see her go, but the replacement was an '06 Altima Special Edition... BTW, the 2.5l Nissan engines for the '06 models are being recalled (all 87,000 of them) for replacement (poor piston ring selection).

Step 1: Materials

Valve Cover Gasket Kit ($13 at autozone, big box with two tubes of RTV and 11 neoprene bolt seals)
--- alternatively, you can buy the preformed gasket for about $30 - if you have the black polycarbonate valve cover, you MUST use this preformed gasket... it saves some time/work in the end though.
Torx Bit - can't remember the size
Socket Set (I think you only need a 10mm)
Philips Screwdriver
Flat Heat Screwdriver
Razor Knife
Brake Parts Cleaner
Rags, turkey bastor -- to clean up oil
Gasket Scrapper

Soap
Hot Water

If your spark plug wells were flooded like mine you may want to replace:
Spark Plugs
Spark Plug Wires

Step 2: Remove the Intake

You'll need your screwdriver to loosen up any clamps.

You really only need to remove the section that bolts up to the TB -- this just makes working faster.

If you do remove, stuff a rag or paper towel in the exposed throttle body opening -- just in case a lizzard or other critter decides s/he wants to set up a new home....

Step 3: Remove Solenoid

I think its an EGR solenoid - regardless, its bolted on to the side of the valve cover. If you can unplug it - be my guest. I couldn't, so I used a socket and unbolted it.

Step 4: Remove Spark Plug Wires Etc.

Pull the wires. Also disconnect the PCV canister and breather hose.

Step 5: Remove Valve Cover Bolts and Remove the Valve Cover

Using the Torx bit, remove the valve cover bolts and their gasket washer ring thingies. I think they are all the same size, so no worries about keeping them in order.

The hard part... Using a rubber mallet, tap the sides of the valve cover... you can also use your hands.... Keep wiggling back and forth until the VC pops off. -- the old gasket material is acting like a glue - so you may want to get a thing razor blade in between the seem and cut some old RTV loose.

Pull the valve cover straight up and this is what you should see... Well, hopefully a little cleaner - but you get the idea.

Step 6: Optional - Suck Out Any Oil

If your gasket failed like mine, you're gonna need to pull some excess oil out of the plug wells. A plastic turkey baster comes in handy here :P I used a pipette - it is what I had.

If there's only a little oil, you can just pull the plugs and let it drain into the cylinder -- it will burn off when you start up. I did this with the little bit of oil I could not recover.

Step 7: Clean the Mating Surfaces

Using the gasket scrapper, remove any and ALL of the old gasket material.

Using a #1 (or maybe #2) flat head screwdriver will help get the old material out of the grooves in the valve cover.

Now, if you can... go inside and put it in your kitchen sink... run lots of hot soapy water and scrub off any gunk that might be in there... Then scrub the outside so it will look better :P If you can't no worries ;)

Then follow up with brake parts cleaner and a rag to clean off any oil. If there is ANY oil, the RTV will not stick and this will cause a leak.

Step 8: Apply the RTV Gasket Material

Follow the directions on the tube of RTV. Evenly apply a bead of RTV sealant on the valve cover. I added a little extra to the #1 and #2 spark plug well. I did this because an oil jet fires on the #1 (and a little bit of #2) spark plug well area. This is what caused it to leak as it did.

Also apply a little bit of RTV sealant on the right side of the head (passenger side). This is as per the service manual... It needs a little bit more in order to seal properly.

Step 9: Put the Valve Cover Back On

This is important. Place the valve cover back on the head exactly where you want it without hitting anything. If you smear the wet RTV, you're going to have to clean it off and reapply.

Once the valve cover is back on, begin putting the bolts back on with their new rubber gasket sleeves. Start with the three center bolts (middle one first). Then work your way outward. I believe the torque spec is 6-8 in-lbs (yeah, thats INCH). The bolts are designed to break should you overtorque them.

You know you did a good job if the RTV oozes out a tiny bit.

Step 10: Final Steps

Now you're pretty much done.

Using your socket, replace that solenoid and any hoses you took off. Replace the intake, breather hose and PCV line. Then let your car sit for 24 hours to allow the RTV to cure. Starting early may break seal and ruin the gasket.

In about 300 miles (or say the following weekend). Change your oil and filter. This is precautionary in case excess RTV came loose or other debris found there way inside.

I don't have a picture for this... so here's a picture of my car's mcstrut setup, rotor, caliper and halfshaft etc.