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Discussion Starter #1 (Edited)
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Hello everyone.

I recently bought a very clean 91 420 SEL, dark grey over a light grey interior, as the 'good' car, a daily runabout for the wife mostly while I drive the 'work' car, a (coincidentally) 1991 also, a little stripper S-10. I hope to get 8 years or so out of the old gal. It's hard up here in the salty north.

Dark grey over a light grey interior, chrome factory rims, sunroof, 69k miles, factory service stamped until 55 or 56k (the one nearest that) then copies of receipts up to recently. The entire engine compartment is covered in what appears to be cosmoline. Right now I only have the one pic.

Although all the fluids I can check appear to be nice and fresh, it otherwise appears very original overall, so I'm giving it the old car onceover: belts hoses wires etc, lube everything, research research research. I'm also awaiting on a copy of 'Buying and Maintaining a 126 S-Class Mercedes'. This site in particular has been extremely helpful. I am wide open to comments and suggestions!

Its super interesting, seeing the difference between 'normal' cars and this beast. So far the shocks on the motor mounts are perhaps my favorite. The 90 degree hood is awesome too.

As I've been replacing parts I've been watching the differences between the new parts and the old ones and thought I'd comment on them, a way for a newbie to contribute :) In no particular order

The tstat. The new one is REIN CTI0019. It does not have the brass bits the old one has. Also, had I known what a pain it was to change I'd have bought OEM at least.

Main coolant hoses. I bought 'real' MB ones. Still, only one actually says Mercedes on it, and they don't seem to be quite as thick as the old ones.

Wires. I used UNITED MOTOR PRODUCTS 9805 - these are 'packard' wires and I've always considered them a premium set. However in this case they were a bit inferior to the existing wires. No spring clip around the bottom of the metal cups, and the boots on the cap end weren't quite as long. They were also a little bit thinner.

The Bosch 7905 plugs appeared very close to the old ones. The cap, rotor, and coil, BOSCH 03227, BOSCH 04177, and BOSCH 0221502433, all appeared to be exactly the same as original.

For the voltage regulator I originally bought AC Delco Professional E675A, then changed my mind and bought the Bosch 1197311028. When I pulled the original I compared all three. Interestingly, it was the Bosch that was redesigned, while the AC Delco appeared to be the same as the original. Which one is actually better? I have no idea. I put in the AC Delco as it seemed a little heavier duty.

And that's where I am now. I put a new radiator cap on and that immediately caused a radiator leak (of course!), so I'm about to install a NISSENS 62727A and will comment on it.

A note on the hose/tstat/belt install - having the radiator out made it 1000 times easier. I removed the fan too (and gave it a light sanding, the surface felt rough). This made such a big difference I feel it's probably worth pulling the rad and fan to do this job even if your radiator is OK.

Any thing else in particular I should be looking for / planning?

Thanks,

Pete
 

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Hey Pete,

Welcome aboard!

Thats a lovely & low mileage car you have and sounds as if you are on the right track..

You'll find the Buying and Maintaining a 126 S-Class Mercedes book will keep you up at night studying!

Well done.

MBL
 

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Yep welcome. And best get the rust proofing spray out. These are durable obviously but the advantage of having an old car is knowing the standard weaker points.
 

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Discussion Starter #4
Many thanks. I WISH the book would get here already!

ianr, I hear you. I used to think I could keep cars running forever but the rust! The last straw was my '85 Town Car. So much refresh work, so little life in salt.

So, once I get the mechanicals sorted, and as soon as I get the underside and wheel wells rinsed out I was planning on taking it to a place that sprays 'NH Oil Undercoating'. I figure why not. I've also paid for a year at a very good local car wash that has undercarriage wash options.

I sure hope it helps.

Pete
 

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Oh I meant to ask - my headlight wiper/washer system don't come on. I had a mechanic give the car a onceover and he said they work if you jump them, but don't appear to be getting a signal.

Any ideas?

Pete
 

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Thanks guys.

I was hoping for a 'yeah, that happens all the time. Just [clean/replace/whack with hammer] the xxxx right by the yyyy - easiest repair you've ever done' answer! :-D

I will print the drawing for when I get to it though. Once I get the radiator / hoses done I have to change the brake control rods (I've getting an occasional light thunk at braking) so I can get new tires and alignment. Then I'll have the game plan for brakes and suspension. Here's hoping the front end looks good, it's certainly tight. I ordered one of Burgsma's seat repair kits too, see how that goes. And plans for a bunch more stuff.

And then maybe fit in work, family, and actually driving the thing occasionally!
 

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Good suggestion! But yes, I actually read the owners manual to see how to do it, no luck.

And my apologies, 'NH Oil Undercoating' it an undercoating company: https://nhoilundercoating.com/

No affiliation, etc. There's a local place here in the Cleveland area that applies it and I'm going to give it a shot.

I see your tag line. I originally wanted to get a diesel MB but this is really the SO's daily driver and she didn't like them. I've been considering attempting to put a MB diesel in my old S-10 if its engine blows - I think it would be pretty neat.

Pete
 

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I'm guessing that's the 'NH' part. I'd love to see your state one of these days. Aren't you the guys that put up your own street signs?

Have you ever seen the YT vids of the guys in India starting their old diesel engines by blowing flame into the intake? It's awesome.

Pete
 

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Geez! They're all over the place around here! Looks like they started in Chichester, about 20 miles from here. They have a dealer just down the street, that I could walk to, where I take my Volvo for the heavy lifting.
 

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Welcome Pete, congratulations on a fine automobile! We had a 420 SEL when I was a teenager in the 90's.

Yes, Dr. Greene's book has been very helpful, and I've learned a lot from Kent as well.

I've had great success with my Nissens radiator for years now, and I only use the MB coolant. When I originally bought my w126, it had the green universal coolant for years, but I later learned it could be corrosive to the alusil blocks/cylinder bores in our cars. My service person at the time said he couldn't see any signs of corrosion from the previous twenty-four years, but I feel better about the MB fluid anyway.

I thought I saw on the forum in the past that there is a place in Texas that makes aluminum replacement radiators for w126s, but so far the Nissens has held up very well with no signs of any problems in at least eight years.
 

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Discussion Starter #15 (Edited)
Thanks Drew! Glad to hear the Nissens is OK. It looked nice and dropped right in. It had yellow antifreeze, nice and fresh. I refilled it with premixed Zetex G-05 (it took 2 gallons). I hope it's OK.

I finally received and read Dr Greene's book. Ian I see what you mean, I'm going to put the mechanical refresh on hold (the main things are taken care of I'm thinking) and start digging down to those rust prone places he mentions. I don't have any of those spots as trouble - yet - just the very slightest of bubbling just below the lower pass side rear window. Time to climb in the trunk. Time to buy a case of preservative!

He also has a picture of the aftermarket wires I used next to the OEMs. D'oh! But they'll do for now.

John, have you used their rustproofing? I'm just taking a stab in the dark. I've been eyeballing Volvo wagons to replace my S-10, just a thought, they're so comfortable too.

Pete
 

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Make sure the plugs you get are non-resistor plugs, many cross-reference parts lists will have R plugs. This will make a difference.

Also - go on ebay and get the good fuses with the brass connections vs. the aluminum parts store ones. Also get some Detoxit and spray on all on the contacts.

If it were me, I'd do a full fuse replacement with new brass fuses, and remove all relays, and spray the whole panel down with Detoxit it.
 

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Thanks. I got the correct plugs.

I also heard about the fuses and immediately bought copper/brass from Ebay. But, they are plastic. So I tried swapping the element onto the old ceramic ones.

No luck - the non-fuse part of the metal is too wide, so it doesn't fit into the groove proberly, so it ends up being a little short.

I think they'd still work, and you might be able to grind the elements down to fit too, but I found a China seller on ebay that advertises copper/ceramics. I'm waiting for them and will post when I get them (anytime soon).

Wow, Deoxit, that's a flashback from my vintage stereo days :) I've been using CRC cleaner, then CRC electrical lubricant. I bet Deoxit is better though. I definitely will pull the relays too - great suggestion!

Pete
 

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If they EVER get here, Hopefully tomorrow

In the meantime I ordered a new ignition cylinder from MB, just in time too, my wife said the key stuck a little yesterday.

Out of curiosity I asked the dealer how much to install it. $375!

Pete
 

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There's reasons why the w126's out-sold all the other MB sedans 2:1 and its really cool you're discovering them. It's a fun journey isn't it? And there's still a ton of w126s out there begging to be saved. One of my favorite corners of the W126 is the front suspension. Who else uses a sway bar for a thrust link? The elimination of a conventional upper A-arm, and a knuckle designed to push the lower joint deep into the load center of the wheel is absolutely brilliant. At the same time, the shock is able to be moved outboard as close to the wheel as practical. Each one of these features improves one or two aspects of the design - reduction of unsprung weight, reduction in the number of parts, better geometry, or better load control. But together it is better than the sum of the parts - a thing of engineering beauty like the late anti-dive trailing rears on the 107s. Hoch-Cuckoo-clock artz!! :) One more unique thing on your car you won't see too often: the connecting rods in your M117 have counterweighted end caps. Dude!
You asked for suggestions - All services of course, but particularly brake fluid change, and Hmm . . . I think in 91 rear self leveling might still have been an option on the 420s . . but I'm old and forgetful . . (standard on late 560 in US) If your car has it, the mineral oil is probably black - if so, show her the love and change it ASAP. It is a fabulous system only troublesome and expensive when service is ignored.
I just got another sedan a few weeks back myself. I think I'm going to need to check myself in somewhere. So see, I can share your joy . . and pain. :))))
Fresh off the trailer. Poor lonely thing:
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During a bath with some kind fondling. Its sick how original this thing is, and 1 owner.
2606440

Its a Canadian '90 560SEL in Smoke Silver/Chinchilla W/Brazil leather. Speedo's km, but in 'mercan-count its 124k mi I've got an 86 420SEL in Diamond Blue/Navy somewhere here among the herd as well.

Best of luck with yours, Grey/Grey is mega.
 
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