Land Rover Repair: Discovery Series I code issues, exhaust flange, vacuum line

Question
John,
First, thanks for answering questions here. This is a great resource. I added to Seafoam to the brake booster vacuum line tonight, while the engine was warm and running, and it immediately smoked and showed wetness at the manifold to cat converter pipe joint, on the passenger side. So, perhaps this is the big issue. Of course you might imagine I would rather find an at-home solution, than take my Disco in for the T-4 diagnosis, so we'll see. Any thoughts, given this information?
Thanks again,
Michael

Answer
If you saw leakage at the joint from the header to the catalyst, you should of course fix it.  The truck is probably making a spitting or tapping noise as a result of the leak.  That said, an exhaust flange leak will not set fault codes, so if you have a code issue, that's not it.

John