Anyone know where I can source the correct part for the coolant reservoir bleeder screw?
I believe it is 13mmx1.5 bleed screw. I've already replaced the reservoir so I just need the screw
the screw is made of hollow plastic fill and if you overtighten, it will shear off.

all of the ones I found online are 10mm and do not fit XKs/F-types etc.

 

I can confirm, LR055301 smaller diameter 10mm and is not the correct bleed screw.

 

UPDATE: There are 2 sizes being sold under the same part number, you will have to ask the seller
to put a micrometer on the plug. Currently britparts is selling it on amazon/ebay

 

Try the plastic bolt commonly used to hold license plates to a car's body.

 

I wouldn't recommend using a license plate screw, you might mess up the threads.

This is also a bleed screw that is suppose to allow some flow from hose to reservoir
even when closed shut.

 

There could be a 50% chance a plastic bolt has the same thread size. Add an 0 ring for seal and drill a hole vertical and horizontal for air flow. Finding the replacement bleed screw, will only come with a complete tank. Just another Roadkill repair!

 

all the wallet rovers have that screw

 

britpart sells the correct size under the same part # LR055301 but be advised most sellers will
send you the 10mm plug which will not fit XKs F-types

https://www.ebay.com/itm/153760911404