Hello all ... I'm new to the forum. Didn't see an introductory post so Im just gonna go ahead and get into it I purchased my 09 xf premium luxury in January and haven't had any problems till now. I had a code for the secondary air pump after looking under the hood I noticed my hose was brittle and broken in half I replaced the hose bought it from Jaguar for $75. Seemed like it fixed the issue except now there is a hissing sound coming from part of the engine I've uploaded a pic and circled the part I took it off made sure there were no cracks or leaks put it back together and when I turn the car off it sounds like the last bit of air is being squeezed out like when you shut off an air compressor. Any help? Suggestions? I'm figuring out I probably should be a jag owner. Thanks in advance.

 

Compliments on a nice clean engine...The 4.2L I'm not familiar with..I'm sure help will be on the way soon.

 

"hissing when the engine is running" or ONLY for a second during shutdown? If #1, you have a vacuum leak, if #2, you likely have no issue at all.

 

If no codes you are OK. Even hearing a hissing does not mean it's a vacuum leak.

Have you checked for codes?
.
.
.