2001 Jaguar XJ8

 

Yes moisture on the coils causes problems.

 

+1, absolutely.

My experience with the overflow tank on my XKR, which is similarly situated right above the coil cover as on my XJR, is that when it starts to leak or let go that it will leak onto the coil cover. I found out my coil cover seals were gone back there. So I had my tank leak, fixed that, and the car was running rough. I lost 2 coils.

My tank went catastrophically on the side of the road while I was pulled over to look why the car was overheating; I was just looking around to see about a leak, and the hotplate welded seam where it was leaking let loose more and I got sprayed with 250 degree coolant on my right arm. Ruined my dress, got in my hair, and burnt me up good; I still have scars. Luckily, my engine was still good after this event; no blown head gasket or warped metal. Just a tank, coils, coolant and a $150 doctor bill.

Oddly, the 8 for $100 coils on eBay work just as good as the Densos they replaced, at least the 3 years now that I've had them. I also have 6 spares in case they crap out lol. Price one Denso coil and they look appealing .

 

you should look at the octopus hose for a small leak which could be spraying a small amount of antifreeze into the engine bay giving the moisture that will get onto the coils. I know because it happed to me