It’s taken well over two years, has caused us to scour vast swathes of Germany in a frantic search for OEM pieces of trim and has consistently taken up a disproportionately vast portion of the workshop, but the Mercedes W116 S-Class is slated to leave Retropower in the coming weeks. It’s been a deceptively complex restoration of an undeniably classy mid ’70s executive icon, which is all the excuse we need to look back at key aspects of the build.

Turning our attention to a classic Mercedes Benz S-Class was always going to be an involved undertaking, largely thanks to the complexity of the car itself. It’s true what they say, big Benzes of this era really were built like a panzer (and were almost as heavy), but then that’s because they had to be – they came with an immense amount of kit by early ’70s standards, and ensuring that it all functioned and functioned correctly must’ve caused Mercedes boffins more than a few sleepless nights. Their solution was quite simple; over engineer everything, then engineer it a little more – just to be on the safe side.

The S-Class as it arrived at Retropower; tatty, complete yet unwilling to run

The upside to this was a generation of bullet proof Benzes. The downside, one that’s become apparent with the passage of time, is that restoring said Benzes is not something to be undertaken lightly, and it would be fair to say that bringing this big Mercedes back to its former glory has been a challenge. The added level of complexity can be found in pretty much every area of the car, from its vacuum operated central locking to the aforementioned interior, the throttle linkage (an work of engineering art) to the trio of oil pressure relief valves on its 3.5L V8 engine.

We stripped and rebuilt the W116’s signature V8 engine, re-using its impressively unworn pistons, con rods and crank

The V8 is also worth looking at in closer detail, mainly as it manages to be complex in certain areas and charmingly simple in others. It’s over engineered (of course), so much so that we’ve actually been able to retain much of the rotating assembly in OEM condition, including the pistons, crank and con rods. In fact the only areas showing clear and serious signs of wear were the bores of the block, a legacy of Mercedes’ insistence on using incredibly high quality piston rings on models from this era. Something had to give with the passing of time and countless miles, and it certainly wasn’t going to be the rings!

The block itself was acid dipped and rebuilt with the hardware mentioned above, but not before we had the bores re-linered, a far more cost effective method than a re-bore for all 8 cylinders, which would have entailed the purchase of 8 new pistons and for which we were quoted approximately £250 each . The heads were also in an impressively good condition, with no real wear to the camshafts. The heads themselves were stripped and bead blasted, then fitted with re-faced valves, re-cut valve seats and new rockers, though we were able to retain the OEM rocker pedestals.

The rebuilt and repainted V8 begins to take shape

It’s a mid ’70s Mercedes at the end of the day, so of course it had its fair share of foibles and nuances, the timing chain a good example. This is both convoluted and massive, thick enough to pass for an anchor chain on a seafaring vessel, with a route that takes in an impressive number of tensioners. It probably wouldn’t have been anywhere near as tricky had we had access to the original manual, but we didn’t, so it was.

We’ve also had the Mercedes’ transmission rebuilt. A three-speed automatic, the ‘box was sent off to a trusted specialist for dismantling, then sent back to Retropower so that its component parts could be blasted and prepared. Everything was then sent back to the specialist once again, this time for assembly.

Well engineered they might’ve been, but Mercedes cars from this eras were far from immune to corrosion, as evidenced by this example

There’s another thing that’s worth knowing about Mercedes offerings from this era, and that’s their propensity to rust. While far from the most challenging bodywork restoration we’ve undertaken, key areas of the W116 were very rotten indeed, the sills, quarter panels, front wings and front end structure being particularly rust ridden. We were able to source part of aftermarket front wings of course, but these proved to be less than perfect and subsequently required a fair degree of re-fabrication before they were suitable to fit to the car.

It takes many, many individual components to restore a ’70s S-Class

The sheer number of parts required to make a W116 also caused a few raised eye-brows, though here we were at least aided by this example being dropped off at Retropower in something approaching a complete state, and the interior was an especially complex area. The good news is that Mercedes can supply many of the clips and fasteners needed brand new (and at great expense), though not the actual interior fabric. We won’t re-tread ground by going over the challenge associated with sourcing enough of the W116’s green velour to re-trim its vast interior, but you can click through to read all about it should you wish.

The upside to restoring a car like this is the satisfaction it brings. Granted, we’re never anything less than over the moon to see a Retropower fire into life, but the complexity of bringing the big Merc back to its former glory has been immense. It’s destined to spend the next portion of its life on display in a purpose built glass viewing area, so it’s just as well that it now looks as good as the day it rolled off the line nearly half a century ago.

The comfiest seats the ’70s could muster – and just as cosseting in the 21st century as they were in 1973!

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