Rusted leaking sunroof pan: 79 w116 300SD
 

So I have had leaks coming from my sunroof for a while now. I had thought until recently it was bad seals, but of course a little research told me the seals aren't meant to keep water our, and either my drains were clogged or the pan had rusted through.

After determining that the drains were clear I went ahead and took the entire sunroof assembly apart, though I have yet to find an angle in which I can remove the pan through a door, so its just sitting in the car. Every corner of the pan is rusted, though the drain nipples themselves are intact. I was thinking of doing a temp fix with either bondo, silicone calking or both.

What I want to do is find an intact replacement to swap in. I have found very little info about replacing the entire pan, and am unsure what models/chassis will fit my 79 W116. Ive read somewhere on these forums that someone took a manual sunroof from a w123 to install in their w116 300sd. Will the entire assembly, pan and all swap in these models?

Any advice or info is helpful. I'm pretty much wingin this.

You can't use Bondo which will absorb the water and compound your problem or silicone caulk which will etch the metal (due to the release of acetic acid which is its curing agent) and weaken the remaining pan.

Use POR15 or its ilk along with fiberglass mesh if required for form.

Don't know about the W123-W116 interchangebility but I'd bet not.

I had my pan out this time last year during a major restoration. I had already removed the front and rear glass so getting it out of the car was not an issue. If removing glass is not in your plans, you might be able to get enough space if you remove a front seat.

As far as restoring yours, I would think if you don't have access to a welder that POR-15 on the rust and some fiberglass on the missing metal might make sense. I did see the complete W116 sunroof assembly for sale this spring but it was priced around $400.

Finally, make sure you do not bend the hollow sunroof cable tube that enters the pan at the rear.

Wow MikeD - great minds think alike!

Or two guys who have gone through the same thing do anyway.

You're not the first person to tell me I had a grate mind or was that a mind like a sieve? It was some kind of a metal structure. Rusty trap maybe?:D

How have you been? Hadn't seen anything from you in a while.

I am planning on converting my 1980 W116 300SD sunroof to manual. I have the entire assembly from a W123 and I think it will interchange, but I'm not totally sure about the frame.

It would be a great opportunity to convert your sunroof to manual if you like that thing. If worse comes to worse and the frame doesn't fit, you can find a good W116 sunroof frame and then cut the "stops" from the W123 frame and attach them to the W116 frame.

Just to warn you, the sunroof frames are really big and I have never been able to pull them from a car without it slicing up interior parts. And that was with the seats laid flat. You have to wedge them out of the front door and the steering wheel and shift knob seem to get in the way.

Squiggle,

I converted my 116 to a manual sunroof. The tube that the sunroof cable rides in was eating my cables after about 25 cycles. A new tube was NLA and looked to be a major pain to replace. I used my existing sunroof and linkage and and the manual "guts" from a W123 sunroof to convert it to manual. Let me know if/when you decide to convert and I'll take a picture of the internals if you think it well help you.

Mike,
The W116 has been the first car I have restored and kept for longer than a year. Unfortunately there's not a whole lot to do to it this winter so I'm not sure how I'm going to keep myself busy. I started going through and fixing little things like loose bulbs and adjusting windows but there's not going to be any massive dis-assembly like years past. I hope I don't get cabin fever this winter.