Not sure where to start searching the forum. 2001 XK8 Nikasil engine. Engine runs great. Never smokes. Strong over the full RPM range. Good compression when I checked it last year.
I know there is an oil leak somewhere on the left side of the engine (as I face the car from the front). I pulled off the sparkplug cover from the left side rocker cover. And found lots of oil (the right side is completely dry). The plug wells are filled with oil. Mostly at the back plug and less and less as you get to the front plug. But, all of them have oil. Where could the oil be coming from?


Front plug rubber has the least oil whereas the back plug rubber has the most oil

Quite a lot of oil

I think this is the source of the oil I see under the car

 

Cyber3D,

Well in my experience, the spark plug seals (item 2 in your figure) never seat particularly well, but any oil getting into the coils and spark plugs, wouldn't spill out under the car engine bay - not clear if that is the problem, or are you burning oil?

A few things to consider
1. Is the full load PCV breather (from the cam cover to the air tunnel) blocked as it should be slightly wet with oil vented from the cam covers. Easy to check by disconnecting the pipe and running the engine to see if it's pulling a vacuum over the hole (may get a DTC though)
2. When was the cam cover gasket last changed? That was the main source of my oil leak. I attach photos showing the problem I found where the gasket was well past it, and the previous installer didn't put a blob of RTV on the flat spot



Once you've checked the above, let us know what you find.

Hairline cracks in the cam covers have been found by others, as the material is vinyl ester plastic. Trouble is that sometimes these cracks don't open up until engine is up to temperature.

 

Oil in the plug wells is almost certainly the seals. In your 2001 they are separate rings rather than the 'pair of spectacles' found in the earlier cars. Replace them all, replace the cam cover gasket and definitely the rubber isolator washers found on each cover bolt (beware OEM are around $2 each and you need 14 each side). These are key to getting the cam cover to fit snugly. At the top of the motor, all these parts bake nicely over time and lose the ability to form a seal. David's picture shows clearly what heat and time does to these parts.

Go easy when torquing up the bolts on replacement: They only need to be nipped to ensure the isolator washers are compressed and doing their job holding the cam cover snug.
Remember the single bolt on each bank that isn't trapped in an isolator (the bobbin-shaped spacer) fits in the top rearmost position else you may skewer the cam position sensor.

Aode06's thread includes a diagram of the bolt tightening sequence and is worth a read through:
https://www.jaguarforums.com/forum/x...1/#post1099831

When you fit the new cover gasket, ensure that the bottom flange on the isolator goes through the hole in the gasket. This will ensure that it bears directly on the head and doesn't nip the gasket in between. Each hole has tiny flaps on the inside which will catch on the lower flange and hold the gasket in place (you will see what I mean when you have the parts in hand). A small dab of high-temp RTV on the head gasket to front plate joints and you're good to go.

Hopefully this work will solve your problem and you don't encounter any hairline cracks - often caused by over-zealous tightening of the cover bolts.

Also, if you can lay hands on a 1/4" socket set, it will make access to some of the lower cover bolts easier. You're lucky it's the RHS cover as you won't have to fight the dreaded dipstick tube

Good luck

edit: If you have oil under the car, then check the high-pressure hoses to and from the engine oil cooler. These can be engine-killers when they let go...

 

Thanks, guys, No more leaks. I for sure thought I had changed the seals last year. But, I found a seal kit in the garage and managed to change them and all is good. Now, onto the other issues . . . haha

 

The designation of left and right side is made from the drivers seat, not facing the car. I don't think your XK8 has a engine oil cooler unless it's an aftermarket add, but there is a transmission fluid cooler as part of the radiator and a power steering cooler in front of the radiator.