Any advice on how to disconnect the small plastic coolant lines that run across the top of the engine and connect to small coolant tank without breaking them? I thought I read somewhere that there was a tool on one of the lines?

 

TSB 303-17 describes the special tool.
The early X308 had one on the part load breather tube on the left cam cover.
It seems like it was deleted around 1999 or 2000 MY

Here is a copy of the TSB and a description of the tool.

bob gauff

 

Or, gently squeeze the top and bottom together with water pump pliers while gently pulling the male end out. Squeezing the top and bottom of the fitting relieves the side tension just like the special tool does. Or, long needle noses can be used to spread the fitting.

 

So that's why I could never find it! I even asked BlackOnyx because he mentioned it in his timing chain page.

 

they aren't too expensive. Get some spares. Most of the time you can remove them, but
as they age, they get more brittle. NEVER drive if one is leaking.

 

Unless someone has done a lot of work changing out hoses you will probably find one of those tools stored in a fitting on the engine. I think all of the cars were sent out of the factory with one on the engine.
My XJ8's was on a fitting under the throttle body and My XK8's was on the part load breather. Take a good look at all of the plastic tubes you might find one sitting in the fitting.

 

Look back to motorcrman's post #2. The tool was deleted in '99 or'00.