This is the second cap to leak within a week, could it be the reservoir that is the problem or another part?

 

Jason,

NOT a lot of info there, except you are in the US, BIG land mass, just like mine

Give us a clue as to the Beast involved please, so we can help you.

 

+1

Jason,

Model, year and market specification (your location gives this detail) are essential information when asking technical questions. As you have already posted a coolant hose question in X351 forum, I expect this is the same 2012 XJ 5.0?

From the rate at which the coolant is being forced out, I'll be very surprised if it's not a blown cylinder head gasket or warped cylinder head. A pressure test will reveal any leaks in the cooling system and a compression test will indicate specific cylinder issues.

Please read the guidance for new members ( https://www.jaguarforums.com/forum/n...ned-up-241802/ ) which answers many of the most frequent questions about getting started on the forums.

Graham

 

yes 2012 XJ 5.0 SC, I replaced the coolant reservoir and bled the system through bleed screw and multiple cycles over the last few days. So far it is looking good and no leaks.
I recently had my upper inlet hose, vacuum hoses, and water pump replaced. I had the cap failure after those repairs and Jaguar tested and said there was nothing causing abnormal pressure (such as head gasket). I’m hoping it was just warped reservoir threads.

 

Keep a close eye on it. Overheating is a Jaguar V8 engine killer.

Graham

 

A very easy way to verify a head gasket leak. The kit is $50 and you can reuse the tester - you just need more dye. https://shop.advanceautoparts.com/p/...500/25961533-P