Drain Pipe Connector
Quick answer: A drain pipe connector is the plastic joint that couples two lengths of sunroof drain hose together, usually hidden behind trim or the dashboard. The hoses push on to it rather than clamp to it. The plastic ages, goes brittle and cracks, and the hose itself shrinks and pulls off, so the connector is a failure point in a part of the car nobody can see.
Sunroof drains are rarely one continuous hose. They run from the corners of the sunroof cassette, down the pillars and out near the wheel arches, and along the way they are usually joined by plastic connectors, sometimes at a bend. The hose is soft silicone; the connector is hard plastic; and the two age at different rates.
What it means
As our write-up on a 2006 Volkswagen Jetta puts it: it is seldom the case that these silicone pipes are in one piece, and often they have a connector. The pipes push on, which is what makes them serviceable and also what makes them come apart.
The four ways it fails
They are worth separating, because the repair is different for each and only one of them is a blockage.
- The hose shrinks and pulls off. Silicone shortens with age, and eventually it pulls itself off the connector or simply works loose.
- The connector perishes. The plastic becomes brittle, then cracks or shatters. On a 2013 Range Rover Sport this is called out as an additional problem on top of the usual blocked drains: the connectors on the pipes become brittle and break, so they get replaced.
- The hose splits. Covered alongside the connectors on a 2004 BMW 5 Series, where the pipes may be blocked at the cassette, at the far end, or anywhere in between, and may equally have shrunk off their connectors or split.
- Somebody has already had a go. On a Skoda Octavia the pipes had popped out of their connectors and been stretched back into place and held with cable ties. It had not worked.
Why it matters
A blocked drain leaks slowly and predictably. A disconnected one empties the whole roof into the inside of the car, and it does it where you cannot see: as the write-up on a 2014 Seat Leon puts it, if the pipes split or pop off their connectors, you may well find water leaking out from behind the dashboard. That is why a wet footwell with a dry sunroof recess is not a contradiction, and why the fault often gets blamed on the windscreen or the door.
Common mistakes
- Forcing a coat hanger or other stiff wire down the pipe. As we say on a Land Rover Discovery, that can easily pop the pipes off the connectors, which turns a blockage into a leak inside the car.
- Blasting compressed air down from the top for the same reason: the hose comes off its connector behind the dashboard and the drain is now discharging into the cabin.
- Cable-tying a shrunken hose back on instead of replacing it. The hose has lost length permanently and will pull off again.
- Clearing the blockage, seeing water run through, and never checking the joints along the way.