Third generation LR Discovery (L462; 2017–present)
Images of a common issue with the current crop of Discos showing where the windscreens are leaking from, and why.
This crackle-glaze patch indicates an issue with the substrate; this shiny appearance is all of the adhesion promoter (primer) which would have been applied to the glass surface before the polyurethane adhesive ( “PUR” ) was introduced to bond the windscreen to the car.
This image shows the ‘cut’ PUR against the crackle-glazed PUR confirming that the issue is not so much in the product, but the application of it.
The PUR in the images has clearly bonded to the car. The problem isn’t there; it’s on the glass surface. The above image shows more of the crackle-glaze (to the left) and the silver band has been exposed by where it peeled off from. The ‘failure’ is either in the application of primer (was still wet when the PUR was introduced) or that the glass surface is – or was – contaminated. Given that the overwhelming majority of leaking Disco windscreens are in the same place (along the top of the windscreen) and that the bond around the rest of the screen is good, the non-adhesion problem is localised and therefore indicative of contamination. This by no means is definitive and is not based on thorough tests in laboratory conditions. However, the telltale signs are present: peeling of primer and/or PUR; the upper trim which comes stuck to the windscreen also peels off easily; when the affected area is tested for contamination there is evidence of something greasy.
The shiny appearance on the image to the right shows the kind of shape you would get if you wiped through a wet product. Furthermore, if you ignore the primer or PUR not sticking to the glass, the trim (which is attached with very strong double-sided tape) also failed to stick to the glass:
The proliferation of this problem in the same model, in the same place and all showing the same characteristics points to one problem.
Moving forward, the correct course of action is to replace the windscreen. This is largely to negate the issue reoccurring as we do not know what the substrate was contaminated with; at what stage it happened; what products were used in the preparation and subsequent bonding of the windscreen, and how good (or not) the rest of the windscreen bond line is. A new windscreen, from Land Rover, properly prepared eradicates any further problems. That said, the existing [contaminated] windscreen can be removed and can be reinstalled. Extra care, appropriate materials and products are needed, but it can be done successfully. Products such as neutralising agents to rid the substrate of all contaminants and a strong adhesive to reinstate the upper trim (it cannot be bought separately).
With the upper trim reattached, the ‘refurbished’ windscreen can be refitted.
Leaking Disco 5 Windscreen: done.