R129 Informative write up.
Found this post on piston heads good stuff, thought it may go somewhere for prospective buyers to view? It wouldn't all fit in one post so did it in 2 I suppose there is no issue doing a copy and paste?
Production spanned 1988 (RHD 1989) to 2001
All cars were supplied with the following equipment:
-electrically operated soft top
-electrically operated seats
-alloy road wheels
-full size spare
-automatic transmission (UK cars)
300 SL: May 1988 to June 1993, m103 motor (3.0l, I6, SOHC, 12v, 190bhp)
300 SL-24: July 1988 to June 1993, m104 motor (3.0l, I6, DOHC, 24v, 231bhp)
500 SL: June 1988 to June 1993, m119 motor (5.0l, V8, DOHC, 32v, 326bhp, after September 1992 only 320bhp)
600 SL: August 1991 to June 1993, m120 motor (6.0l, V12, DOHC, 48v, 394bhp)
SL 280: February 1993 to June 1998, m104 motor (2.8l, I6, DOHC, 24v, 193bhp)
SL 320: February 1993 to June 1998, m104 motor (3.2l, I6, DOHC, 24v, 231bhp)
SL 500: June 1993 to June 2008, as 500 SL above
SL 600: June 1993 to May 2001, as 600 SL above
SL 280: June 1998 to July 2001, m112 motor (2.8l, V6, SOHC, 18v, 204bhp)
SL 320: June 1998 to July 2001, m112 motor (3.2l, V6, SOHC, 18v, 224bhp)
SL 500: June 1998 to July 2001, m113 motor (5.0l, V8, SOHC, 24v, 306bhp)
AMG produced several variations. The 500 SL 6.0 AMG and the SL 60 AMG are the most common (although still hugely rare, less than 100 imported to the UK) and essentially feature 6.0litre versions of the m119 V8. This was specified as producing 386bhp but common consensus has it that the engine makes about 420bhp. These cars came with AMG suspension which is fair amount stiffer, AMG wheels (17" on early cars, 18" on latter, split rims on both) and usually (but not always) AMG bodywork. Post June 1998, AMG produced the SL 55 AMG with a 356bhp, 5.5l version of the m113 V8 (still used in the SLK 55 AMG) and the remarkable SL 73 AMG which featured a 7.3l version of the m120 producing 525 or 575bhp. Both of these latter cars were special order only; it is not clear whether any were imported to the UK or manufactured in RHD. AMG also manufactured cars to customer request: notable is the SL 70 AMG, again a V12. I am aware of one customer order AMG RHD SL in the UK: it is badged SL 730 and features a 525bhp version of the m120 V12. It is black with black leather and does not have AMG bodystyling. It appears to have been built in 1996 but registered in 1998. If anyone has a pukka SL73 AMG for sale, please let me know: I'll have it.
1988 to 1995: most cars are supplied with two-tone bodywork and orange indicators; bumpers and sill covers are of a simple, squared-off profile; three small rectangular vents behind front wheels; bookish wing mirrors; concealed exhaust; orange and red strongly ribbed tail lamps.
1994: single-tone paint, albeit lower body panels and bumpers have a satin finish; white and orange front indicators (I think this is correct).
1995: first facelift: single-tone paint, albeit lower body panels and bumpers have a satin finish; white indicators; bumpers have a softer shape and a series of feature lines; only two ovoid vents behind the front wheels; bookish wing mirrors; concealed exhaust; all red strongly ribbed tail lamps; re-profiled door cards to accommodate side airbags; ESP available; panoramic top available as an optional extra.
June 1998: second facelift: all bodywork finished in gloss; exhaust visible through cut out in rear bumper; exhaust given a dark grey trimmer; ovoid SLK-style wing mirrors; soft all red tail lamps; 17" wheels; bigger front brakes; nappa leather upholstery standard on all cars. These late-model cars have very full specifications as standard, especially the 500.
THE R129 IN USE
For a high performance roadster, the R129 is remarkably practical: less so if the bench mark is a family saloon.
The 4-seat passenger compartment is quite spacious and very comfortable up front. The front seats are large with generous and well-padded squab although the backrest can lack lumbar support on a long journey. The footwells are wide and spacious, too.
There is a wide range of electronic adjustment of both seat and wheel. Drivers up to about 6'4" ought to be able to get comfortable; taller men might find there are height and legroom limits.
The cabin as a number of lockable storage compartments, so notwithstanding the lack of a glovebox in most cars (the passenger airbag taking the usual space), it is usually possible to find a place for everything.
It is a different story in back. The rear seats are not completely useless but are best left to small children if the journey is anything over a few miles. It is possible to squeeze two adults in there, but only if the front seat occupants share the suffering. A single adult might be able to find more comfort by sitting across the rear seat but undoubtedly this is less safe. The rear seat backs can be folded down to make a substantial luggage platform when not required. The rear seats have only lap belts.
The boot is good for a roadster, large enough to take luggage for two for a fortnight's touring holiday.
A child seat can be installed on the front passenger seat. On early cars, this may require the deactivation of the front passenger airbag; on later cars you will need to obtain a seat fitted with AKSE transponders which tell the airbag that a child seat is in place. According to Mercedes-Benz, a rear-facing child seat can be installed on the rear seat but to my mind the arrangements for this are not particularly satisfactory and the size of most models of seat will leave the front seat unusable so far forward does it have to be moved.
The car is not fragile and may be parked outside all the time, although obviously it will deteriorate faster and its bodywork may require more regular waxing than a garaged car.
By today's standards, the R129 is not a particularly large car although if you intend garaging, you should check it will fit. The front doors are very long and so considerable extra width may be required to open them.
The extremely high level of comfort makes the R129 ideal for long distance use. It is quiet with the hardtop in place (less so with the soft top); the suspension is absorbant of road surface irregularities, being of very long travel spring with firm damping. It is easy to drive, demanding very little of its driver in ordinary use, with light but adequately communicative steering and other controls, good visibility and very good directional stability. The driving feel is essentially modern, although perhaps it is a little softer than its 2011 equivalents, many of which seem designed more for the Nurburgring than the highway. The fuel tank will give a cruising range of 350 to 400miles at a steady 90 to 100mph. Indeed, this kind of use is the model's natural habitat.
While the R129 is not a cheap car to run, nor is it completely unaffordable. It is more mainstream than exotica. As with any car, the key to keeping costs low in the long term is not to skimp in the short term. Regular and preventative maintenance according to a considered and budgeted program will reduce the risk of an expensive surprise almost to zero.
These are not expensive cars to insure. Your premium depends less on the car and more on you, where you intend to keep the car and what you intend to use it for. With a clean licence, a recent history free of fault accidents and a garage, you should be able to insure your SL for social, domestic and pleasure for less than £500; less than £300 if you keep the mileage below 10,000. My policy allows myself and my wife to use the car for commuting and business purposes for 20,000 miles per annum; I picked up 3 points in October 2006 and had a fault accident (in a different car) in December 2007; the car is garaged; I have a substantial no claims bonus; I pay less than £400.
They are not horrendous to fuel. There is no major difference in fuel consumption between the models: the worst you'll get is 18mpg (from a hard driven or town-based 600) to 25mpg (from a feather-throttled V6). This is because they are all the same shape and all roughly the same weight: no matter what engine they have, the same energy is required to move them. There is an argument that the V8 is the most efficient because in normal use it just never has to work very hard. Late models, with the m112 and m113 motors, are more efficient, but only a bit more.
Service intervals are lengthy. Early cars call for a lubrication service every 9,000miles or annually and a more expensive inspection service every 18,000miles or every two years. Later cars have the ASSYST system under which an on board computer determines when a service is required. Typically this will be about every 15,000miles or 18months. If you want the car to last a long time, I would have it serviced at least every 10,000miles or every year. The automatic transmission should be serviced every 40,000miles. Brake fluid should be changed every two years; coolant every three. Spark plugs (of which there are 12 and 18 respectively on m112 and m113 motors) require changing every four years or 50,000miles (I think). This latter can be an expensive job: check it has been done recently to any car you are considering buying.
Engine oil capacity on the V8s is 8litres; slightly less on the I6 and V6; more on the V12. Engine oil is quite pricey these days! The m112 and m113 have twin plugs per cylinder, doubling the cost of a spark plug change. Brake pads and discs are not out of the ordinary range. Suspension components are shared with the saloons and so are quite reasonable. High quality pattern parts are available from the German manufacturers such as Bilstein and ZF group; often these manufacturers supply Mercedes-Benz and so using their parts can save you a fortune with no detriment to your vehicle's condition. The things that cost money on these cars are those which are bespoke for the model and available only from MB: a xenon front headlamp is £750, for example; I know because I have bought two. If you're on a really tight budget and know what you're doing, you can obtain parts from breakers. Poor examples of the model are now so cheap that it is economical to break them. Beware the quality of parts from such sources, however: the cars found in breakers tend to be in much worse condition than one's own and they are, after all, no more than the sum of their parts.
My fast-driven 500 wears its tyres down to 4mm within 15,000miles, sometimes a bit less. I suspect a less-demanding motorist will get 20,000miles and more from a set. A full set of Michelins runs me less than £800.
The R129 is generally very well-built but it must be remembered that it is highly complex even by today's standards. All aspects of the car's design are high performance; the 5.0litre variants acceleration, speed and braking to match contemporary supercars; the suspension and braking systems have a considerable amount of work to do, the cars being heavy and the range of operating conditions being wide. In order to function at the highest levels of operating efficiency and performance for which they were designed, these cars require consistent and thorough maintenance. Being high-end cars, parts are correspondingly expensive. These were £60 to £100k cars when new in 1988 to 2001 and nineties pounds were worth more than today's pound. The servicing they require remains that of a £100,000 car even if they can be bought for 5% of that sum.
To make matters worse for the potential owner, because these cars are so well made, they can take years of neglect and under-maintenance before they breakdown. You will never catch up with backlog maintenance: never. The £4,000 SL is a money pit which will never be right. You are much better off buying a car at twice the price that has been maintained without regard to cost. My own SL500 cost me £28,000 in March 2003 with 40,000miles on the clock (it cost its first owner £86,000 in May 1999). Since March 2003 I have driven 165,000miles, taking the total well over 200k, but have spent approximately £45,000 on servicing, maintenance and repair (including tyres). The car is as good today as it was in 1999 (hostage to fortune).
The m103 is bulletproof. There is no more to be said about it.
The m104 is prone to failed head gaskets. By prone, I mean it will probably need doing once at around 100,000miles. From 1993 to 1996 the m104 also suffers from disintegrating engine wiring looms. Most will have been replaced by now. The m104 is otherwise pretty bulletproof. You should note that there is a big difference between early and later m104 engines. The first were badged 300 SL-24 and have a capacity of 3.0litres; the second were badged either SL 280 or SL 320 and have capacities of 2.8 and 3.2litres. So far as I can tell, they are completely different engines. What they have in common is a lovely, traditional straight-six DOHC feel, a lot like an English sports car motor of the sixties. You need to rev them to get the best out of them: but boy is it worth it!
The m119 is the finest engine ever made. Poorly maintained cars can suffer blocked camshaft oil feeder pipes. The timing chain, tensioner and guide rails should be replaced every 150,000miles. This is a purist's engine.
The m112 and m113 V6 and V8 motors were a disappointment after their joyful predecessors but in use have been proved every inch their equal. Both V6s and the V8 are relatively fuel efficient. Both are lighter than their predecessors and more torque rich: though slightly down on power they are faster. V6s suffer from a disintegrating crankshaft balancer. Have it replaced with the updated part; if it disintegrates, it will take the timing case with it. V8s weeps slightly from the left bank cam cover.
Mercedes-Benz has never had to replace a m119 or m113 V8 under warranty: never, that is how good these motors are.
The m120 V12 is much maligned but again is a fine, purist's engine. It gets a bad press because when it goes wrong it is expensive to fix. There are four reasons for this. First, the m120 is a rare bird in the UK and very few people are familiar with them. Second, it is a tight fit even under the long bonnet of the R129. Third, it represented the pinnacle of available knowledge and the best of the best is made of expensive parts. Fourth, there are two of everything, one for each bank. They don't go wrong. People say the 600 is no faster than the 500: they're wrong. The 600 is much faster, especially above 80mph.
The 722.5 5speed transmission is less robust than the unburstable 4speeder; but you would have to be unlucky for it to let you down.
The 722.6 5speed transmission can suffer from fluid leaks around the diagnostic connector. If left unchecked, fluid flows along the wiring harness and into the transmission ECU where it causes an expensive failure.
All transmissions require servicing, whether the service schedule calls for it or not.
There is nothing surprising about the brake system. Later cars have bigger Brembo brakes. The 06/1998 SL could brake from 60mph to 0 faster than any other production car at that time.
There is nothing surprising about the standard suspension system. Shocks should last 100,000miles and more; springs indefinitely. The cars eat front anti-roll bar bushes. These should be changed about every 20,000miles. They are very cheap: about £1 each (plus an hour's labour for installation). If you can feel a knocking in the steering, chances are it's these bushes. The rear subframe mounts need changing now (the youngest cars are ten years old) but are unlikely to have been done. It's not a terribly expensive job but makes an huge difference to the handling; likewise the diff mounts, nobody ever changes these but they make an enormous change to driveline refinement. On my 206,000 mile car I have replaced all of the rear suspension arms (the cheapest way to do the bushes), the front control arms and the front shock top mounts. Steering dampers are a common repair item.
The optional ADS system (standard on 600s) gets a bad press because a failure of its valve body can be very expensive to repair. However the system is relatively simple in its mechanical operation: in place of shock absorbers, at each corner there is a strut, the function of which is to maintain the level of the car. The damping function is performed by inboard spheres which split by a diaphragm on one side of which is suspension fluid on the other side of which is nitrogen. It is essentially a Citroen-type system with added ECU controls. The most common failure is a bad sphere: they wear out just like shock absorbers; they costs little more to replace. Those who have sampled both systems swear by the benefits of ADS.
The electrical system, including the elctro-hydraulic hood, is very reliable. Headlamp washer and wiper motors are prone to failure for some inexplicable reason.
The air conditioning system (if fitted: it was an expensive option on early cars) likewise is reliable. The most common failures are the condensor (which eventually succumbs to damage, being at the front of the car) and the evaporator temperature sensor (which fails, and causes the evaporator to ice up, blocking the flow of air into the cabin).
Ideally your car will have clean, uncurbed alloy wheels in the original finish.