Obviously the window sits flush without rattle when closed.
However, when the door is open, the window has some play in it, as if loose on its track or whatever else holds it tight.

Passenger side is tight.

How can I tight glass?

 

It could be:

1. where the glass fits into the channel (red arrow)
2. the 'X' lift mechanism (green arrow)
3. the guide channels (blue arrows)



You're going to have to take off the door card to see where the slack is.

Be VERY CAREFUL with the lift mechanism when testing it with the door card off. It could easily slice a finger off.

Graham

 

Sounds like a worthy reason to simply pass an auto glass shop or body shop..lol
Some things are worth paying for.

 

Make sure they know how to remove the door card. Lots of Jaguar plastic that can be broken if not done properly.

XK8 Door Trim Panel 76 34 01.pdf

Graham

 

Anthony, +1 on Graham's advice. OTOH you're going to have to get behind the door card for something else sooner or later. Seems like a big job the 1st time, but it really isn't. You'll have it off in less than 5 min. after a time other two. Plus it's a hell of a good feeling figuring out the problem, that x10 if you fix it yourself. Too bad it will be so rainy for next few days, makes it an inside job. John

 

Could be just a window glass bumper that needs attention.

Look here for how I fixed mine

 

+1 on that, when I replaced the buffers on mine, the second time, I glued them in place.

 

Plenty of videos on Youtube how to remove the door card. It really is quite easy to do. Look for some videos by rev Sam actually I will see if I can find a link for you. Here you go
Before you remove the door card put the window half way down so you can see the bit that actually holds the glass firm when you have removed the card.

I have taken mine off many times. Make careful not of what screws came from where though, I sellotaped mine to the bit I took off takes seconds but saves mins.

You will have to reset the windows when your finished but that is easy as putting the window all the way down....... hold button down. You hear a faint 'click' then all the way up and hold........ faint 'click'. Jobs done.

Another one for you to watch

 

One comment on Frankc's excellent write up. You only need to reset the window if you disconnect the power. Many of us, myself included, have messed around inside the door once or twice without disco'ing the power. The shear number of warnings on this site plus an observation of that window mechanisms power in motion will convince anyone. It is just not worth sticking your hand in there. OTOH, you can safely view the window motion with power on.

You didn't describe the movement in detail but there is an adjustment screw that when is the loosens allows the window to move around an imaginary axis that goes straight through both door windows.

Good luck, John