The parts finally came, so I will get to it this weekend.

It is an exact OE quality replacement. I was surprised that a $40 part came with the gaskets and sensor. Now I have a couple extra gaskets to return.

Anyone have input on the vertical coolant tower cap? Can I remove and reinstall it without having to buy a new o-ring?

 

It's helpful to include a picture when you are unsure of what a part is called -- not sure what cap?

Another thing to keep in mind when replacing failed parts on old newly purchased luxury cars -- the previous owner may have not purchased an OE part. It's not uncommon for later owners to replace one substandard part with another. Second and subsequent owners are less likely to purchase OE parts -- or maintain the cars properly. Epoxy, on a vital part is an indication of someone who is looking for a cheap (hopeful) fix. Doing it on an X308 shows a lack of understanding -- as any coolant issue can quickly escalate up to a failed engine with the Jaguar V8.

 

When I completely drain the coolant, does this drain the heater also (and then I just need to follow the procedure to make sure new coolant makes it to the heater)

The thing circled in the photo below is the cap I was inquiring about. (although I already took it off at this point)

 

That "cap-thing" is your thermostat housing

 

If the ring is still good inside and that is what you have then sure, but I'm of the survivalist mindset idolizing Cuban automobile ingenuity, and others may warn otherwise.

More importantly, the plastic thermostat housings are notorious for cracking (mine did, replaced it with a metal one), so if yours is original from 19-years-ago and you remove the housing from the engine be ready for an escalation of challenges should the plastic crack and you need to order a new housing before your car is drive-able again.