Mercedes-Benz Forum banner
1 - 20 of 57 Posts

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #1 · (Edited)
I thought I'd start a thread to detail the areas to check if you're buying or own a W126.

Some lucky people don't have these worries but we have salt on the road here and I guess lots of other places do too.

The old W126 comes from a time when rustproofing techniques were not so great. I come from a coastal place with sea air, and you should see what happened to cars down there, back in the day.
However they were really well protected for the time. New things were used and they last really well.
Like most cars though, there are plenty of spots to be aware of.

Underneath in particular or inside rear wheel wells etc, that stuff they coated the metal with is really thick. I think it's for sound proofing too. I recently stripped some off and found clean, shiny brand new metal. Amazing really at this age.
However, if it gets damaged the metal underneath has trapped moisture against it and can rust freely while still seeming solid. So be aware.

Then there are areas that have almost no protection, like underneath the rear window. It's fine for ages, but rubber degrades and when the window seal needs replacing, moisture gets in and creates havoc. It's actually sometimes worth being proactive and having the window out to clean and treat. A new seal from MB a must.
Coupes suffer from this now than saloon cars, because of the angle of the window. Either can get this though.

The other thing is that there are lots of areas in the structure of the car that are double skinned or layered etc, for strength I guess. So welding could be complicated in those places if needed.

Feel free to add to this thread, I'll just bung pictures up every now and then.
 

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #2 · (Edited)
Rear Window

The worst area is probably the rear window. The seal gets old and let's water in. I had a new one put in my 420se, bought from MB for about £100. About the same money for an experienced guy to remove window at bodyshop and refit once done.

Looking up through those round holes and feeling with the fingers, is how to check.

I had only two small areas that were easily dealt with, on the lip on each side. Actually not a bad bill at all to be honest. The rest is great so I'm lucky.

My SEC is shockingly rotten there. In a place not used to rust problems it would probably be scrapped. But here, although it's bad, the car is well worth repairing.
The picture with the most rust is my car. Window is currently out and it will have the whole lot cut out and repaired. The shiny paint was me doing my best to try and minimise the spread beforehand. It's POR15 paint, which is a fantastic product, if used properly. (Depends on preparation.)

I have a new seal, replacement trim while we're there since the original isn't great, and the lip repair panel from MB. The whole rear bulkhead and parcel shelf all in one used to be available but I don't think so any more. It was over £1000 ages ago and that would a mental job indeed.

The rear screen can get misty around the edges. This doesn't necessarily mean the area is rusty but it's pretty likely. Likewise, no clouding is not a guarantee its fine.
 

Attachments

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #4 ·
That's a great one, and those bits are a very common area that can need attention. Actually the whole section may still be available from MB. We had a member who had his replaced due to the car having sentimental value. Impressive.

The cowl drain tube means the area is often wet, and the general moisture gets inside through the slots.

Its another area that can look fine because of that thick coating.
 

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #5 · (Edited)
On my SE I stripped most of the front wheel wells including this area, to bare shiny metal - some rust had started. Up in the crevice between this area and the frame rails there was some small damage to the undercoat and rust had started there too.

I got rid of it where I could with wire wheels and treated with Bilt Hamber rust converter. Then POR15, lots of coats with lots of drying time. Then a load of coats of 3M stone chip.
The peace of mind was worth the effort. It took a while though because of all the coats.
It wasn't too bad down there but would only have got worse obviously.

Another area which can be deceptive and look solid because if the thick coating.

Also, I don't know if maybe it might have made a very small difference, but just trying to slow it down with spray on underseal is pointless, it just carries on rusting - only you can't see it. Then you have a horrible mess to clear off when you tackle the area properly.


Pictures of that area found on Peachparts, which is another useful forum.

Also from the Peachparts forum.

PeachParts Mercedes-Benz Forum - View Single Post - Attentions W126 Owners - Rust Alert
 

Attachments

·
Outstanding Contributor, Vintage Moderator
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro 300sel5spd R+C107galore
Joined
·
24,124 Posts
With several rusty w126, I look forward to contributing.

Hazy rear window = bad seal and moisture desperation.

All Mercedes of the era have several drains that need to be clear to allow moisture to drain out. Where are they?
Door bottoms?
Trunk wells x3
Gas tank filler drain
Firewall down vents... into the frame rails?

I don’t know, but these are talking points you can add to.

Top Body rust I’ve seen:
- rear wheel wells, tops and backs I’ve seen
- front fenders in front of the wheels above the bumpers
- door bottom rust
- front frame rail rust


I’m sure I can add more later.


Sent from my iPhone using Tapatalk
 

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #7 ·
Yes please Fonzi. If you can snap pictures, would be good.

Drains definitely need to be kept clear. Another set is the sunroof drain tubes. These can rust too, the junction where the metal stain tubes join the rubber.. You can use things to poke down, a thick bass guitar string I heard about once seemed a good idea. There's a drain on each corner of the sunroof cartridge unit. So four total.

My drains always seem to stay clear, I think because the car is used and kept pretty clean/washed.

The drain tube on each side underneath the windscreen wiper cowling are good to keep an eye on too. Rust happens there sometimes if the drain tube gets blocked and the water builds up. The cowling comes off pretty easily, you need to take the wiper arms off too.

I had a bit there but caught it very early, thanks to someone in the forum here posting it up as a potential.
 

·
Registered
'91 560SEC, '98 SL500
Joined
·
2,273 Posts
Dealing with Rust on a nice car can be challenging and requires a patient and skilled hand to properly address. After living in the north-east rust/snow belt for 15 years, I've owned my fair share and sympathize with any owner that has to deal with this.
 

·
Registered
68 250S, 91 300se, 98 SL500, 450SEL 6.9, 14 CLS550 Past MB's; 300SD, 300E, 300TE, 190E, ML420
Joined
·
4,657 Posts
The rear lower control arms will rust below where the spring sits.
beneath the battery tray and same spot on other side as leaves and such get in there.
the front subframe behind the front wheel will rust is the undercoating cracks or gets damaged.
The ends of the front torsion bar will rust right off. it sits inside rubber bushings and you cant even see it. you can buy weld on replacement tips to fix that easily.

Good news is the W126 is way better than the W116 chassis that is 100x more prone to rust.
 

·
Registered
1985 300 TD 1981 300 SD
Joined
·
618 Posts
I'll throw in a few comments along with pics from the body work I did on my 81 300SD last year.

Under battery tray

Under the lower trim on both fenders and doors

along with in front of the wheels as previously mentioned

Inner fender seams.
There were a few more spots but mostly surface rust that cleaned up, the only welding I did was on the front fenders.
It really wasn't in bad shape for a 36 year old Ontario car.
 

·
Registered
1991 560Sec
Joined
·
89 Posts
Just checked my rear window spot as you said and sure enough plenty of rust. I'm assuming removing the rear window is the only way to really take care of the issue correct?
 

·
Premium Member
1991 560 SEL, 1989 560 SEC EURO, 1989 560 SEL and 1985 280SE Euro
Joined
·
424 Posts
1) Check sunroof drains in each corner of the sunroof. Remove headliner trim for best access. While you’re in there lubricate rails and mechanism with MB GLEITPASTE.
2) Next up is the BATTERY TRAY. remove headlamp washer reservoir and the battery. Unbolt battery tray. Clean area with baking soda solution to neutralize battery acid and repair / repaint as needed .
3) Renew body cavity wax spray ( l like Eastwood’s amber color wax spray, replicates factory look)- spray in access holes at trunk lid lip and hood , remove left and right cornering lights and renew wax inside front fenders.

These are fun and rewarding projects that pay huge dividends in the future-

**CREDIT TO NIK GREENE’s W126 guide as the motivation for these and so many more DIY / save the W126 projects
 

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #13 ·
Definitely all of the above. There are loads of grommets to inject wax in if you want. The other day while it was n the ramp at a garage I took full advantage! Filled up the main rails and plugged the grommets back in.

Also loads of grommets in places like rear wheel wells etc. I spray wax in those even though the original wax is still waxy. I am loving Bilt Hamber Dynax stuff. Theres one with a great extension and 360 spray nozzle.

That rust under the battery tray can mean water ends up in your rear footwells! Mental. Water leaks in there and own through the bulkhead area and slowly fills up the floor cavity. (Below the actual floor,) Eventually it comes out and travels neatly down the electrical conduits into the rear footwells.

@ilyad - I'm afraid so.
 

·
Registered
1985 MB 500sel (Euro)
Joined
·
852 Posts
Yikes. I thought I was in pretty good shape after catching and fixing a lot of rust after the car was on salted roads up north. In Florida, no salt except for sea breezes. Much better, but now I see its time to go over it all again. Many thanks for this warning and an earlier one about replacing entire fuel lines from pump to distributor. Ta
 

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #15 ·
The funny thing about rust I've found in all my meddling, is that it can be stopped. But sometimes no matter how hard you try it'll reappear. I have another car I've removed all rust, shiny metal, then all kinds of good stuff over the top with every precaution. Guess what, lol...

And then other times it's done. Preparation is everything I'd say. Especially with stuff like POR15. Once that stuff catches properly it is all kinds of awesome. But if it doesn't, it doesn't matter how many coats.
It'll either still rust underneath, or the stuff will peel off in sheets. Or both! Haha.

Sometimes at least you've slowed it down.

I do like to avoid any treatments that are only for psychological value though. Normal sticky underseal is a good example of that.
 

·
Registered
560SEL 560SEC E320 Cab. MB Metris Van ML 320 ML320CDI/gone 300TD 300TE 300SDL, 300D, Unimog 406
Joined
·
2,544 Posts
Rust is interesting. For the most part, it slows itself if not disturbed. I have found unprotected steel implements that have weathered for 150 years with only a light dusting of surface rust and no structural degradation. And, thin sheet metal auto body rust is typically only unattractive unless is perforates into ducts or channels.

But, there is a lot of paranoia around rust, as if that nearly worn out W126 that will end up in a scrap yard in 5 years anyway is somehow toxic because of it.

Relax folks. If the target car already has 150k on the clock without a complete refresh, a little wheel well rust is gonna be the least of its troubles.
 

·
SuperModerator
1986/1990 W126
Joined
·
17,876 Posts
Discussion Starter · #17 ·
Indeed. I like @kevdupuis positive attitude there. Sort it out and move on! The car does obviously need to be worth it to the owner though.

If my front tower in the wheel well started falling off, I'd still probably see about having a new one welded in. I'd just count it as maintenance, I like the car enough. Depends on the individual case though - and obviously if you're in a non rusty part of the world with plenty of cars to choose form, you could more easily just buy another.

Does help the 126 is pretty big and very strong. Bits at the ends could drop off and it'll still work :)
 

·
Registered
1985 300 TD 1981 300 SD
Joined
·
618 Posts
Indeed. I like @kevdupuis positive attitude there. Sort it out and move on! The car does obviously need to be worth it to the owner though.

If my front tower in the wheel well started falling off, I'd still probably see about having a new one welded in. I'd just count it as maintenance, I like the car enough. Depends on the individual case though - and obviously if you're in a non rusty part of the world with plenty of cars to choose form, you could more easily just buy another.

Does help the 126 is pretty big and very strong. Bits at the ends could drop off and it'll still work :)
It does help for me that I love working with metal, I've helped build and restore a number of vintage cars and aircraft over the years hence the Hurricane mk XII in my avatar.
 

·
Registered
1990 420SEL, white ; 2002 VW Eurovan GLS
Joined
·
127 Posts
one more item to look at are the aftermarket chrome mouldings around the wheel wells. They are typically attached with screws that go into drilled unprotected holes in the fender. If you have those on your car it might be a good idea to take them off, check for rust underneath and protect those drilled holes.
 
1 - 20 of 57 Posts
Top