Detailing the 280SL Engine

[NYC-MB280SL]

I have a 1968 280SL and am about to undertake a major detailing of my engine bay. I've noticed that many of the restored SL's (including those done by MBUSA Classic Center) are now being shown with a yellow finish on the metal pipes, bolts and gas lines. I assume this is some sort of zinc oxide finish to prevent rust.

Does anyone have any experience or helpful hints on this process to share?

Why in a world so obsessed with original detail, would so many high end car owners make this modification from original?

Peter Paris

[wwheeler]

That yellow finish is the original color for this generation of cars. It is called yellow zinc or possibly could be yellow CAD. There are many posts about this on this site. Over time, the yellow finish (chromate) vanishes and leaves the silver zinc or CAD plated finish. Once that plated finish wears away, the pipes will start to rust. The yellow chromate is a protective coat for the vulnerable zinc plate finish. Nothing lasts for ever. But the yellow chromate is for sure correct on most items in the engine bay.

[Shvegel]

Peter,
Research is key to a good job if your goal is originality.  There are many changes that occur not only at year breaks in production but at mid year points as well.  Start by searching "original 280SL for sale"  When you search there will usually a photo of the VIN tag or body tag.  Try to find a VIN as close to your's as possible.  After spending hundreds of hours researching my particular niche in the production chain here is what I figured out.  Original cars are usually more accurate than restored ones.  Ignore any sales brochures you may see online as many cars were spruced up for the brochure photo. 

Save everything that comes off the car and gets replaced.  Even old clamps may be of a design that is no longer made.  Original spark plug wires can have their wire replaced very easily and be more correct than new ones. 

If you are really into the hair splitting details you will notice little paint swipes at various places under the hood.  These are referred to as Dotology and are the marking to indicate that a fastener or assembly had been checked for tightness.  Document them and put them back.  Below is a photo of the dots at the back of the brake booster.

Start by going here:  http://historic.motoringinvestments.com/MainPage.htm   Go to Mercedes for sale and down to the white one labeled as the "Holy Grail"  Although this is a 1969 you will see many of the details are the same as your year.   Use these as sort of a benchmark as to what a truly original car looks like then start looking for the 1968 you need.

[teahead]

http://historic.motoringinvestments.com/Gelson280SL.htm

[Shvegel]

Teahead,
I like the original photos before restoration of the Gelson car for those of us with late 70 or early 71 cars because it has a lot of deep photos and not just the surface ones.  However, a couple things to be aware of in the restored photos are the rubber plugs on the inner wheelhouses should not be there as the holes were left open on the later cars, the alternator between the housings was a clear varnish and not red Glyptal and I believe the serial number on the frame rail was simply stamped in over the paint and doesn't have the "Box" around it like the earlier cars. I am curious how your's is? 

This is a pretty nice 68 with some small issues like those horrid hose clamps.  All clamps should match(Authentic Classics sells sets) except the power steering return hose clamps which are of a special design.

https://scottgrundfor.com/sale-1968-mercedes-benz-280sl/

[49er]

 Have posted this photo many times and easier to just do it again then try and find one of those posts Picture taken of mine a few months after delivery. Castrol sticker put on by dealer.

John

[MikeSimon]

Interesting! I always though the cars had an emission sticker of some kind on the valve cover from the factory. Mine still has the remnants of it and I cannot find a replacement. That has kept me from refinishing the valve cover.

[49er]

Interesting! I always though the cars had an emission sticker of some kind on the valve cover from the factory. Mine still has the remnants of it and I cannot find a replacement. That has kept me from refinishing the valve cover.

Here is a poor quality B&W taken the evening I brought it home from the dealer. Sticker was on the other side. I kick myself that I didn't take dozens of pictures back then but again, I never thought I would still be driving it 50+ years later .

John

[Shvegel]

Mike,
The valve adjustment stickers began in 1970.  Your's being a Euro model has only the valve adjustment and timing sticker.  Mine (I believe) being the US  version has both the valve adjust sticker and the US Emissions family sticker as well.

49er,
Thanks for clarifying the Castrol sticker.  I always wondered about that since your's was the only one I have seen.

[Tyler S]

Mike, See here. For US late version
 https://www.authenticclassics.com/DECAL-MERCEDES-BENZ-EMISSION-CONTROL-280SL-8-p/auth-004780.htm

[neelyrc]

For those following the “paint”, “no paint”, hood latch bolt debate, note the body color paint on John’s hood latch bolts.

[Benz Dr.]

I noticed that the safety catch isn't painted either.

[49er]

I noticed that the safety catch isn't painted either.

 It is painted but just a dull black. Maybe shinier when new?

John

[Tyler S]

The safety catch is dark cad plated (dichromate). Here is a NOS one

[49er]

I stand corrected, thanks Tyler

John

[114015]

Here is a poor quality B&W taken the evening I brought it home from the dealer.

What I am always wondering about, John,

is why your car - which is clearly a US-Version (code 49/1) - doesn't have any sort of emission control relays or stuff behind the battery.
All US-version 280ies should have that..., even the late-style 250ies US had that to some amount..., so why not yours??

https://www.sl113.org/wiki/Electrical/EmissionControlSystem

Just very much wondering...,
Achim

[Tyler S]

Achim, Its all there. The only emissions item on the late 250, early 280 was the fuel cut solenoid. And that was controlled by a microswitch only. A relay for controlling that system didn't appear until very late 1968 production. So in his photo is the enrichment relay, cold start relay, and wiper relay next to the washer bottle. Looks identical to my late 250sl.
Tyler

[MikeSimon]

Thank you for the link, Tyler! They indeed had the label I am looking for!
I ordered it for $14.-, but they charged $12.65 for shipping Something that fits in an envelope and mails for 55 Cent. Put a red flag next to them on my list of vendors.
 Anybody have the same experience with these guys?

[Tyler S]

Mike, That is most likely some sort of shipping software at work. Perhaps send them an email and see if they can ship it in an envelope and adjust the cost.

When buying items for the cars I try to make it a habit to have a running list of additional items (want list) so that shipping charges get combined.

[Shvegel]

Mike,
Are you sure that label is right for your car?  Look at CO etc.  almost positive the Euro cars have a different label.

[MikeSimon]

Pat:

As usual, I was too quick, got too excited. And not being at home did not help. Upon checking the decal, you are right, of course. My original is (was) quite different

[Pawel66]

Mike,
The valve adjustment stickers began in 1970.  Your's being a Euro model has only the valve adjustment and timing sticker.  Mine (I believe) being the US  version has both the valve adjust sticker and the US Emissions family sticker as well.

49er,
Thanks for clarifying the Castrol sticker.  I always wondered about that since your's was the only one I have seen.

Can you tell more about it? How exactly these stickers looked like for Euro version and where were they placed? I was chasing this once - it seemed Euro cars did not have that sticker. I would be very interested how it looked like and where was it placed...

[MikeSimon]

Pawel, I have been chasing that sticker for quite some time without success. As you can see in the picture I posted, there is not much left of it and I cannot say exactly what was on it. As you can also see in the picture, the sticker/decal is on the right side of the valve cover, sort of next to the Mercedes star, between the two mounting bolt cut-outs. And it does not refer to the M130 engine, but the vehicle applications 280SE/8, 280SL/8 300SEL/8. Right along the line of my mystery cylinder head, which says 280SEL/SL

[Shvegel]

Mike,
Have you contacted the Classic Center in Germany?

[Pawel66]

Pawel, I have been chasing that sticker for quite some time without success. As you can see in the picture I posted, there is not much left of it and I cannot say exactly what was on it. As you can also see in the picture, the sticker/decal is on the right side of the valve cover, sort of next to the Mercedes star, between the two mounting bolt cut-outs. And it does not refer to the M130 engine, but the vehicle applications 280SE/8, 280SL/8 300SEL/8. Right along the line of my mystery cylinder head, which says 280SEL/SL

Ok, thank you! At least I know what I am chasing now and the location! I will start digging too.

[Pawel66]

I have these two stickers.

I know the tune-in one (white) is not correct - wrong engine and it looks different a bit from the one on your picture.

And the yellow one - I have no idea if it was used on W113 and if so, where was it placed. I asked this question before, but we did not know...

The system cannot recognize PN 1065840740 nor 1085840740 nor 1305840740 from your picture.

What we are lloking for is similar to the one on the other picture (this particular one is for W115, 116 and 123).

[450sl]

My 280sl 1970 sticker

[MikeSimon]

I think the original sticker I have is very similar to the one you have for the 127/129 engine. It just does not refer to the engine but the car. And some details you cannot read anymore may well be different.

[Pawel66]

Mike, your original sticker had this big image of crankshaft and piston - it is the other graphic series vs. my for 129 or yours for M130. I would be digging for that as well as I know what i am looking for. Maybe I will stick the sticker from your other picture, just for now.

Is the CO value for idle correct on this sticker?

Do you recall the yellowish sticker anywhere in your car?

450sl - thank you, I think it is the emission sticker. From what i know these were not applied for Europe.

[MikeSimon]

Pawel, not really sure what you're saying as far as similarities between the stickers. No, the CO value is not correct. My original sticker has 2.0-3.5% and I have not seen this on any other new sticker available.

[Pawel66]

Sorry for not being clear. I meant the way of showing engine drawing on the sticker for the diesel engine and your original sticker - looks like a new graphic used in stickers of a subsequent issue across the engine types. That is what I think it may be - of course just my supposition.

[Shvegel]

NYC-MB280SL,
Here is a brochure photo for your car or one close to it.  I looked it over and it is accurate and a good guide. 

[alpina]

Is the one I reproduced not what you need ?
https://www.sl113.org/wiki/uploads/Restricted/EngineeringTags.pdf

[Pawel66]

Well, it is different than the old one shown on the picture by Mike...

[Shvegel]

Alpinaltd,
The one you reproduced is a US market Decal.  Lower CO and different timing specifications.

[Shvegel]

OK,  Getting back to the OP's question about restoration tips.  Here are a few more assuming that you are going for accuracy according to Mercedes Benz Club of America (MBCA) guidelines.  The guidelines are original parts or whatever Mercedes Benz is currently supplying.  Hoses for example must carry Mercedes Benz stampings to be considered "Correct"  The battery since the original tar topped Varta is no longer available must be a genuine Mercedes replacement which is currently a white case.  Almost all the plated parts under the hood are Yellow Cadmium plating but since Cadmium is fairly poisonous Yellow Zinc is an acceptable substitute.  The exceptions are the straps that hold the coolant expansion tank with the radiator cap on it, The strap that holds the power steering reservoir to the bracket, the wing nut and washer on the power steering reservoir and the battery hold down bolts and nuts. This is not a complete list but will get you most of the way there.  The original radiator cap will have a "100" on it and should be retained.

As far as I know there are only 3 Black Oxide finished parts,  The bolt that holds the alternator adjusting bracket to the engine, The eccentric bolt at the very back of the power brake booster and the big bolt at the front of the crankshaft that you will most likely leave alone unless you are replacing the front seal.

Hose clamps have been covered here extensively.  Basically, they all need to be of the same type except the clamps on the power steering return hose which are special clamps.  Authentic Classics (Staten Island?) sells complete sets of Norma clamps as the original Gemi clamps are not in production.

A couple things are pretty much unplatable unless you have specific tools or knowledge.  The big solenoid right on top of the intake manifold (CSS or Constant speed solenoid), the big solenoids on the back of the injection pump, the small solenoid on the far right on the engine(cold start injector) all don't like being immersed in plating chemicals and are all expensive to replace. 

If you car is an automatic you will most likely have a switch on the side of the throttle body that has a brown bakelite cover.  Use care removing the wires since it is easy to crack the cover and it's price comes with 3 zeros.

The pipes that run from the injection pump to the injectors must be plugged before plating as the plating chemicals will cause the pipes to rust internally and can actually clog to the point of stopping the fuel entirely.

Pretty much the high points for now.

[NYC-MB280SL]

Thanks for sending the photo.

Do you have any idea how to go about plating the gas lines? Do I need to send it out or can I do it my garage?

Thanks,

Peter

[Shvegel]

You can do the plating in your garage but honestly it is cheaper and easier to send it out.  Usually two or three hundred to do it all.   That being said I have a plating line in my garage.  I like being able to pull stuff off, restore it and put it back together.  It also allows me to plate the "unplatables" things like solenoids and switches that might get destroyed without proper care.  The down side is plating stuff is a caustic mess and pretty much everything in a 3 foot radius will rust.  I have pretty much lost half my 17 foot long workbench to it.   

If you still want to plate your own stuff I can talk you through it.  Eastwood makes some pretty good kits and I have figured out a few tricks on my own.