W123 rust prone locations?

[Ducati]

Where are the locations on a 1983 W123 300D that are most prone to the formation of rust? I have a rust free car, formerly from Santa Barbara Ca., that I am now using as a daily driver here in the rainy Pacific Northwest. What precautions should I take, over & above frequent washing?
Regards...

[Ken300D]

One place that will rust in just about any driving environment (except maybe in the desert if the car is garaged) are the undersides of the rear fenders. The shape and curve of the fenders just behind the rear wheels is such that the painted area is exposed to sandblasting and rockblasting from road debris kicked up by the wheels. I'll bet if you go look you'll at least see chips in the paint. If you let this go without touchup, the rust cancer will start. Get down low enough to look UNDER the fender right at the point closest to the tire.

Another thing that can happen, particularly in a rainy environment, is that with age the old-style rubber gaskets for the windshield and back glass crack and leak. Water will run down and settle in the floorpans. After a lot of rain you should pull back all the floor mats and look for moisture. Reasonable results can be had with aftermarket windshield sealant, but best long-term results are probably had by having a glass shop redo the seals.

There are drainage points in the trunk fenderwells that should be cleared and kept open. A vacuum cleaner (especially a shop vac) is good for this. I think there are drainage points underneath the rocker panels (below the doors) too.

Battery tray is subject to acid leakage eating away the paint, and then rust cancer can start there. This can be severe enough to eat away at the firewall.

Rust bubbles can often be observed starting underneath the trim/rub strips along the sides, and under the trunk badges.

I had the start of some rust in the spare wheel well. There is a rubber plug there that had rotted away in my car.

I've read from other posters that the drainage slots directly under the hood hinges need to be kept clear. Too much water there apparently can spill over into the inside of the car - the floorpans.

The design of the jack lifting holes strikes fear of rust into me. If you use the jack, you know you're gonna scratch the insides of these "pipes". Not to mention that something (maybe the stress of lifting a ton) seems to crack the paint around these things. The later cars (W124) have plastic plugs that go into the jack lift holes - I might get some for the W123, its the same exact jack. I haven't quite figured out preventive rust-proofing here.

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There's nothing like the heavy metal design of strong German steel in the W123. I just wish they had hot-dipped the whole thing in wax.

Ken300D

[Ducati]

Thank God that MercedesBenz are made with Krupp Industries heavy gauge steel rather than the Russian steel that Italian cars are made of. Do you use any spray-on products like Waxoyl or simmilar, and what have your results been?

[DieselHead]

Ducati,
Also be careful of rust and rot appearing on the underside of the driver's side rear trailing arm. Rust has almost completely eaten away the bottom of mine. It's obviously a crucial part/area and it's pretty expensive to replace.

Alex

[vince]

Lots of rust prone areas on the 123:

1) Rocker panels, particularly around the forward jack points, but also internally
2) Under all the side trim, particularly at the bottom of the doors, at the rear, where the stud passes through
3) Bottom of the doors, in the channel for the weatherstrip
4) Bottoms of front fenders, front (under bumper) and rear (especially under thr small molding at the bottom)
5) The hood, under the front and in the seam along the sides
6) Under the windshield and rear window weatherstrips
7) The rear floors, near the outboard side
8) The rear quarter panels, in the seam between the quarter panel and the outer wheel well (along the wheel arch), and at the lower rear

In addition to the areas mentioned in the previous posts. It is a shame, but the 123 (and earlier cars) area prone to rust. And they WERE dipped, injected and swathed with protective wax at the factory.

[Ducati]

What spray-on products have members of this forum used to prevent rust? Does anyone have home remedies that work well? I was told to brush a little clean motor oil around in the trunk. Would that work?

[Mr. BILL]

There is a product called POR15 that really works great. A lot of the BMW 2002 restorers use it. It simply is painted over rust and stops it dead.

It aint cheap, about $35.00 a qt. but it works and you don't have to completely remove the rusted metal. I used it on my son's old BMW trunk and it is amazing. I think I posted about it (POR15) 4 or 5 months ago. If you cant find it, look at www.firstfives.com.

What is Waxoyl and where do you get it? How do you apply it.

Is there a spray wax that should be applied around the wheel wells, door-bottoms, etc., to fight off salt corrosion? I'm in Michigan, so we get plenty of salt on the roads.

Thanks.

[Ducati]

Waxoyl is a wax based undercoating that is sprayed on undercarrages. I bought it this summer at the BMW dealership in North Vancouver. I first used Waxoyl in 1980 when I had it professionally applied to a 1968 Dodge Dart GTS that I had just had a minor restoration done to. That was in Winnipeg, Manitoba,
where as much salt as is used in Michigan is applied to the roads during their long winters. It kept that great old pony-car from rusting for the next three years (when the car was totalled by drunks running a stop sign in an Olds 98).Waxoyl works well at retarding rust, but cant save you from retards.
This summer I bought two one litre bottles & brushed it on the entire underside of my rust-free 300D in hopes of preserving her. So far, so good...although we rarely use salt on the roads here in BC as our winters are temperate and rainy, unlike the deep freeze that you get in Michigan. I also use a variety of waxy oil-like products that I find at Wal-Mart, Lordco (a local auto parts store, not a franchise of churches) and Canadian Tire. I experiment, and try something new every time, and keep my trunk, rear wheelwells, under the battery tray, floors beneath the carpeting, inside trunklid seams, and anyplace that looks it might be a good place to spray, using info on rust prone spots from advice in this forum. Some stuff is black. I dont like it and wont buy it again. Some stuff is amber coloured, displaces water, and is thin enough to spray down between the chrome around windows and underneath the taillights. It works with capillary action; that means it climbs uprward and gets into far reaching crevaces. This spring I will have a bit of greasy overspray off my paint, but I would rather do that than discover a rust bubble starting in some spot, like under chrome trim, or underneath a taillight. I am sure that there are dozens of types of wax based capilary action rust prevention sprays available, and that brands that we dont have in Canada are available in Michigan. I buy a can a month, and just spray anywhere that I feel paranoid about rust starting. I cant even list the names of all the stuff I have used keeping my 300 and my rust-prone Alfa Romeo GTV treated and rust free. All work - some work better than others.