Sunroof blocked drain CL500 C216/W221

[dldb]

My drivers side sunroof front drain is blocked leading to water in my footwell, screen pillar etc.. I have so far tried some nylon fishtape, including with a sharpened brass end, and a steel coiled drain clearer, with a fair amount of force, twisting, pulling and shoving with no result. The blockage will not budge and seemes to be towards the lower end of the screen pillar, judging by how far I can get the tape in (goes 2 or 3 times as far on the passenger side which is not blocked).

I have also pulled back the wheel arch trims and can't see anything blocking the drains on them, the engine bay drains all work.

Have also tried sucking and blowing with a vacuum cleaner. Not tried my air compressor yet (might it blow off/rupture an internal hose?).

Can't think of anything else to try. I could put some drain cleaner down but would worry about what damage it might do to steel, aluminium, plastic and paint.S

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[Plopy]

What I use is Electricians Fishing Tape (its what they use to pull wires through conduits etc.} and I have used a straightened out coat hanger.

 

[oldguy57]

I've used plastic coated curtain wire or if this fails copper coated welding rod. Be careful though drain tube can be easily damaged. You're sure it's not the bulkhead drain adjacent to the bonnet hinge being blocked? I had to use welding rod going up from behind the arch liner to clear this one.

 

[optimusprime]

Dont use force . If you do, you can push off the rubber drain hose in the door , then you will be in deap crap.

 

[dldb]

Thanks, can't get this to move even with my wire spring type drain cleaner attached to a drill. I am beginning to suspect a previous garage has lost a drain rod. I am currently unable to rod it the other way, upwards, as I can't work out where the exit is. It is somewhere behind the front wheel arch trim, I have removed the two plastic pins and peeled it back and shoved a load of fishtape down the working side, more than enough to come out somewhere but I can't see it. Will try again at nigth with a torch.

I have removed the A pillar trim and airbag, there is no sign of the pipe it must be inside the pillar. I haven't pulled the roof trim yet.

3 backup plans:
1) alway park with the driverside up a slight slope so it drains ok from the working hole.
2) seal up the sunroof in some way that doesn't look ugly (like tape), and can be removed without damaging the paint or glass roof edge trim.
3) drill a new drain hole and feed a pipe through the inside side of the A pillar, either to the windscreen drain with a reed valve or back into the wing cavity, also with a reed valve.

 

[SL03WLY]

I used one of these, did the job but I did pour water down the drain too as a lubricant to avoid the hose popping off

 

[dldb]

Thanks for all the advice. I think I have fixed this now. I still can't get the fish tape all the way through on the drivers side but water does seem to be draining.

For future reference here is what I did:

I undid the 2 plastic pop bolts at the bottom of the plastic wheel arch liner, also three plastic nuts with built in washer from the arch, so that I could pull the arch back.
I put the car on ramps on and high suspension setting. I undid two metal self tapping screws and one plastic nut (same as the wheel arch nuts) on the horizontal flap behind the wheel arch, which then hinges down and forward allowing limited access to the wing insides, if the wheels are turned fully. Then I could make out where water was draining from on the working side. It is a rubber tube 15mm OD which terminates high up in the front wing, 6 inches from the top of the wing, pointing forward inside a compartment. No access from the engine compartment that I could see. There is a large oval hole in the sub panel inside the wing where you can just about reach in and feel the tube. On the working passenger side the rubber joker valve, supposedly on the end of the tube, was missing. I fed the fish tape all the way down and measured it from the sunroof drain hole to the hose end - 130cm.

Same procedure for the blocked side. I pulled off the joker valve at the end of the hose - it was full of soft mud. It is quite large - 20mm OD. I could only get the fish tape down from the sunroof 84cm, and up 38cm. So about 8cm where it would not go, assuming both sides have the same length of run. Now the water does drain but I haven't had the chance yet to compare it to the working side. With hindsight I think it is worth pulling the joker valve as an early step. Moreover I haven't replaced it - it doesn't seal fully even when cleaned up so I don't think it adds much to stop air being forced up the tube when at speed. Maybe it's there to stop water coming up the tube - in case the car falls in a river! Note it is almost impossible to rod upwards with any force - I think I would have to remove the wheel and arch liner completely to have a chance at that.

Oddly the hose seems to have a ridge inside it, logitudinally, I could feel it.

I do need to get the car on a more level surface and test the drain rates at each side.

 

[merc estate]

well done

 

[dldb]

Thinking about it, undoing the bottom horizontal flaps was only necessary to spot where the drain came out. If you know where to feel you can remove, clean and replace the joker valve without that - so no need to put the car on ramps and get underneath.