Hi. I recently acquired a 4 Litre V8 Jag and it was misfiring periodically. It got worse after a storm, so I decided to change the spark plugs. An ordeal! I(n doing so, I discovered that under the cover on one side, it was full of oil. The other side was filled mainly with water, but with oil down the shafts the plus sit in. Should I start worrying or go straight to panic mode? Can someone please tell me what should be happening here?
Cheers

 

4.0 or 4.2?

If 4.0 worry about (i.e. inspect immediately & change as needed) the tensioners / timing chain guides etc!

The coils may well be toast with those contaminants, sadly, but you can get COP testers if you want to be more sure.

 

The oil is from leaking valve cover gaskets. A new set of gaskets should take care of that. I’ve had this happen on my ‘02 V6. Surprisingly, the coils were fine after spraying them out with aerosol electronic cleaner.

If in a pinch for time, you could just clean the oil from the coils and plug wells for now, until you have time to replace those gaskets. They aren’t going to fill up with oil again immediately. That’s where I am with my car right now, waiting for nicer weather before tackling this big job.

The water you found is rainwater. Check the seal between the hood and cowl. I think Jaguar put out a bulletin about the rainwater problem. Maybe somebody else remembers it.

If you find any of the coils bad after a good cleaning, swap the suspect coils with ones from known good positions. If the fault follows, make sure to get a quality name brand replacement. Stay away from the no-name eBay specials. They have very poor reliability, even right out of the box.

 

Thank you, that's really helpful. I'll have a look around for the rain water solution, as it clearly go considerably worse after rain. I'll order myself a new set of gaskets also. Dealership prices in Australia are directly related to Kings' ransoms, can you suggest somewhere in the UK who offers sensible pricing and will ship parts?

 

Try SNG Barratt, one of the forum sponsors.

You'll need to replace the cam cover gaskets and spark plug boss seals. Whilst the cam covers are removed, inspect the secondary timing chain tensioners to see if they're the original plastic parts. If so, the primary and secondary timing chains, guides and tensioners must be replaced using the correct tools to avoid catastrophic engine damage.