VW T5/T6 sliding window leak fix

The Problem

The sliding windows leak at the front lower corner when it rains, running water into the cabin and floor, caused either by debris blocking the drain holes in the plastic trim or by the plastic casing not being properly bonded to the glass at the factory. Multiple owners had OEM windows replaced under warranty two or three times only for the replacements to develop the same leak. This affects sliding windows across the T5 (2003–2015) and T6/T6.1 (2015–present) ranges; the drain-hole design is broadly the same across these generations, but confirm the exact layout on your own van (confirm this applies to your T5/T6/T6.1 generation), as trim and aftermarket window suppliers vary.

Solution

1. Slide the glass panel fully to its open position, then continue sliding it past the normal stop so it disengages from the runner channel — the panel lifts free of the lower track rather than unscrewing. Work slowly and check for any retaining clip or screw at the end of the track before applying force (verify the exact retaining mechanism for your window before removing, as it differs between OEM and aftermarket units). Avoid scratching paintwork or cracking the glass.
2. Clean all rubber seals thoroughly with soapy water.
3. Locate the three drainage points in the plastic trim: two slot-shaped holes and one circular hole at the front end of the trim — the circular hole is visible without removing the glass.
4. Use a thin strip of plastic (not metal, which can scratch the paintwork) to clear any debris from the two drainage slots.
5. Fill a syringe with water and flush the circular drain hole until water runs through freely. The amount of compacted debris that comes out can be substantial even on relatively new vans.
6. Inspect the join between the plastic casing and the glass; if there is an unsealed gap, press black Tiger Seal sealant firmly into it all the way around, forcing it in as deeply as possible.
7. Refit the glass panel carefully, re-engaging it into the runner channel in the reverse order of removal, and allow the sealant to cure fully before exposing to rain. As an ongoing measure, park nose-down where possible so any water that does get in drains toward the circular hole rather than pooling.