Rust in sliding door channel

[Levin]

Hi all,

I bought a 2012 Caddy a few weeks ago, and it's proving to have been an excellent purchase.

The only issue I've spotted is to do with the side sliding door, specifically in the channel in the sill along which it rolls. The paint has been shredded down to bare metal in this area. Unsurprisingly, this has begun to rust. I sprayed some wax sealant in a few days ago and left it. A few uses of the sliding door and it has lifted this again, exposing the same surface rust. Spraying it was never a long-term plan, but I wanted to test the source of the problem. I'm now reasonably confident it's the door.

What has happened with the door, and how can I solve this? Prior threads which I've found via Google refer to other threads in the forum's Technical Section. I don't have the requisite posts to access these threads, and I know access won't come instantly when I hit 6 posts.

Sorting the surface rust will only attack the symptom, not the cause. Once the cause is fixed, my plan is to coat the affected area with a rust converter (like Bilt Hamber's Deo Gel - unless there's a better product), and then repaint the clean metal. If, for some reason, it couldn't be painted and left tidy, am I right in thinking replacing the sill would be the next step? Sounds extreme, and I don't plan to go down that route, but it's better to hold all the cards when it comes to solving problems.

Thankfully, it's a SWB with one sliding door. Small mercies, eh?

[BenT]

Congratulations on your purchase! Glad you like it.

If it's any consolation, I've had mine since it was 7 years old, now it's 13 and has had the same rust issue since I bought it. I've just greased it (can't remember what with) and it doesn't seem to have deteriorated. You could sand the rust down and then prime it, then paint it and simply stop using the side door to prevent problems, but this may not be the best solution. If VW couldn't make the paint last, can we?

[Rob.]

Is the bottom roller working correctly? One of mine had seized, meaning it was just dragging itself and wearing through the paint. New roller unit was only a few quid, though I haven't got round to sorting the paint damage yet

[Levin]

Is the bottom roller working correctly? One of mine had seized, meaning it was just dragging itself and wearing through the paint. New roller unit was only a few quid, though I haven't got round to sorting the paint damage yet

I will take a closer look at this to see if the wheel in the roller is moving freely. Before you changed yours, did you notice that the sliding door was difficult to close? Mine puts up a fair bit of resistance if opened to its full width. The two things may be totally unrelated. If this is the cause, I'll keep a close eye on any replacement roller. If they're prone to seizing I'll try and prevent it.

Congratulations on your purchase! Glad you like it.

If it's any consolation, I've had mine since it was 7 years old, now it's 13 and has had the same rust issue since I bought it. I've just greased it (can't remember what with) and it doesn't seem to have deteriorated. You could sand the rust down and then prime it, then paint it and simply stop using the side door to prevent problems, but this may not be the best solution. If VW couldn't make the paint last, can we?

It's proving excellent so far, barring this one issue. I didn't even realise this could happen before I bought it. Other vans I've driven (Berlingos, Transit Connects, etc.) I haven't noticed the same issue with. It must be something to do with how Volkswagen designed their sliding doors. It's reassuring that the issue sounds slow acting but I'd like to nip it in the bud. While I don't use the sliding door anywhere near as frequently, I've found it useful on a few occasions. VW might not have been able to make the paint last working to a budget, but the aftermarket (or even just the knowledge on here) might be able to.

[Dislexicdonkey]

It will more than likely be due to the lower roller being seized or collapsed as previously mentioned, I’m about to replace mine and I’m sure the quote was around £30 from tps. Replace that then get the rust seen to before it gets beyond just surface rust.


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[Rob.]

Yes, 1 door was definitely much harder to move than the other. Slides lovely with the new roller.

[Matto216]

There is a proper repair kit for this and I believe a TSB from VW. The official repair consists of having the paintwork repaired and then a stainless steel strip being stuck inside for the roller to ride on instead of the paint. I bought the strip recently to sort mine out.

[Levin]

Do you happen to have a part number for the stainless steel strip, or photos of it fitted? Preliminary investigations today suggest the roller is at fault. I'll get a replacement ordered but would be interested in what Volkswagen introduced to fix this.

[Nicklouse]

There is no factory fix. It is down to the owner to replace parts that wear.

One problem is people who spray lube on to the rollers rather than replace them. All this does is create a grinding paste thst re,ones the paint and promotes rusted out pannels.

[Ukrutony]

There is a proper repair kit for this and I believe a TSB from VW. The official repair consists of having the paintwork repaired and then a stainless steel strip being stuck inside for the roller to ride on instead of the paint. I bought the strip recently to sort mine out.

Where did you buy that strip Matto?

[Matto216]

Got mine from LLL Parts. Part number is 2K0 843 713.

[Levin]

There is no factory fix. It is down to the owner to replace parts that wear.

Has to be said though, it's not wonderful design. This issue surely cropped up before the 3.5 facelift yet the roller seemingly never changed until the end of the Mk4 lifespan. My intention is to do this once and do it right, so I have a replacement roller ordered as part of the process.

Got mine from LLL Parts. Part number is 2K0 843 713.

Many thanks for this. Do you happen to have a photo of it fitted? I might look into buying the same once I have the problem area fixed and am satisfied the area is clean.

[Matto216]

I don't no. I haven't got round to doing mine yet. I can see you don't have access yet but there is a thread on here with the detail in.

[Ukrutony]

Got mine from LLL Parts. Part number is 2K0 843 713.

Thank you for info! Gonna get that

[Levin]

Turns out the roller in the sliding door was moving freely, just grimy. It would appear a previous owner might have replaced the roller without cleaning the channel up. The metal was cleaned up yesterday and Dinitrol RC900 applied to convert rust and provide protection. After leaving that to cure overnight, the channel received a coating of smooth stone chip and fresh paint. The stone chip ought to provide a more durable layer of paint should the factory colour be eaten through again.

All the same, I won't even open the sliding door for a week or so, in order to let everything dry fully. There's always a possibility of marking on the fresh paint from closing the door today, but it was only closed once. When I next open it I'll inspect the channel for any marking and touch it up since, beneath everything, there's a good layer of Dinitrol to keep the metal clean.

Once I'm satisfied the issue is solved I will see about the stainless steel strip mentioned earlier. No point in covering up the issue until I see the affected area has been returned to good order. If anyone happens to have pictures of it fitted, that would be greatly appreciated.