Featuring Quality Restoration Help For Mercedes 300 SEL 6.3 Owners And Enthusiasts
J Haynes Auto TechnicsEirene Garage
TEL: 01903 500000
Kienle AutomobiltechnikD-71254 Heimerdingen/Stuttgart
TEL: 0049 7152 52827
Star Motors1694 Union Center
Maine Highway Rt 26
TEL: 001 607 786 3918
The Restoration of the Mercedes-Benz
The original owner of the classic car was 1960/70's pop icon Donovan. The restoration of the Mercedes-Benz took approximately two years, although of course work is always on going to keep the car up to standard.
This webpage and some others on this website are designed to provide help and advice in maintaining and restoring these flagship Mercedes-Benz saloons.
For many enthusiasts, motoring journalists or just general admirers this model was and is still classed by many as Mercedes-Benz flagship Saloon. Perhaps it is the timeless elegant styling that has helped it maintain this position, or maybe the mighty 6.3 German V8 fuel injected engine shoehorned into the body which has had more influence in its status.
Whatever way you view the car it cannot be denied that this model of car which was designed in 1967 was very advanced with its fuel injected engine and self levelling air suspension. Built in times gone by when more emphasis was on quality components. This model was for many years the fastest accelerating saloon car available worldwide.
For those interested in the full restoration story then please click below.
Carrying out the Restoration
Carrying out the restoration took two years. Shortly after the restoration, it was featured in a few magazines as well as mentions on the national radio shows Bob Harris Show on Radio 2, and Capital Gold. The car was also been featured on the Mercedes Enthusiast calendar, and has also been on display at Mercedes-Benz World Surrey in 2007.
It is a wonder that the car was still around to restore after its hard life especially as it was stored outside in a field at the mercy of English weather for approximately five years after Donovan sold it.
The car has been restored using original parts, although the points and condenser have been replaced with (link to Pertronix page) Pertronix electronic ignition. This was fitted to achieve a more reliable ignition system which is adjustment free.
To retain the original feel and period celebrity vibe of the car most of the leather interior was kept. I felt this was important, as although carrying out a restoration I wanted to retain some of the period vibe. The leather has been re dyed and is regularly coated and kept at a good humidity to keep it supple. Despite some small blemishes, the leather is in very good condition for the age and the previous very hard life of the car.
Many people hiring the classic wedding car like the fact that, they will be sitting on the same leather seats as Donovan and George Harrison once sat. The interior wood sections have been restored, and most of the chrome work has been re-chromed. Many people like to experience that most of the original interior is still in place.
Hire the Classic Mercedes JMO 9K
As can be seen from the long rear doors, the classic Mercedes is a car to be chauffeured in. Anyone who hires the classic Mercedes-Benz JMO 9K is very soon aware of the extra legroom, which is very useful for a Bride with a large wedding dress.
The large 6.3 litre, twin camshaft fuel injected V8 engine delivers plenty of power and torque. Acceleration of 0-60 mph is approximately 6 seconds. On a constant 60 mph you can achieve around 12 mpg. Driving around town is approximately 8 mpg. It is possible to cruise at 85mph quite comfortably.
There were only approximately 650 of these classic Mercedes-Benz cars made in right hand drive. Over the years most have been broken up mainly due to a combination of very high restoration costs, technical complexity and hard to locate spare parts. At present market prices (2006- 2020) it is often uneconomical to fully restore these cars as the restoration costs outweigh what they are presently worth.
This Mercedes-Benz 6.3 is one of the best right hand drive models in existence. The car is complete with the original sales brochure, logbook, pink card, many tax discs and MOT certificates, as well as the original German oval shaped plates. There is also a photograph of the car parked next to a Rolls Royce used by the Beatles. The car continues to attract lots of attention from all ages when on the road.
Hire the classic Mercedes JMO 9K, and feel the period vibe.
Restoring aluminium window and windscreen trims 'Chemical Brightening'
Many enthusiasts reading this will no doubt have polished aluminium surrounds on their front and rear windscreens and window surrounds. Often these are either scratched or quite tarnished. In many cases when it comes to restoration, some sections are still available new, but many are not. The chances of locating these sections second hand, which are about forty years old with a decent shine and dent free are fairly remote. These sections, can be restored back to the same finish. Try to locate trim sections without dents in, as it is expensive to have the dents removed. It does not matter if the section you find is badly tarnished or with small fine scratches as these will polish out.
These sections are not just chrome plated or polished and lacquered as many think they are. The process is called 'Chemical Brightening'. The restoration of your aluminium section involves polishing it until it is smooth all over and free from pits, scratches etc. The section is then placed in a chemical bath where it brightens, hence the name 'Chemical Brightening'. The section is then anodised to stop it corroding. The whole process is not that expensive and does not take that long, as far less work is involved than say something like chrome plating. Years ago in England there were quite a few companies operating this service but due to changing health and safety regulations many have closed down.
Cleaning of various different steel items
When it comes to cleaning up various different steel items, it is nearly always best to have them grit blasted and sprayed with a zinc primer or hot zinc spray. This provides a decent rust free surface all ready for spraying. Grit blasting can save you much time and is a far better way of cleaning. For large items the whole item even a body shell can be soaked in a bath of acid to remove paint and rust.
As most of you are aware this is often an expensive process due to the work involved in re chroming. There are cheap places to get items re chromed especially in some countries abroad. But be warned!! Most of the cheaper places often do not carry out all the preparation and nickel-plating fully prior to the final chrome plating. The other thing to bear in mind is would you be prepared to send your classic car parts abroad to places that might not speak English, and trying to sort things out if something did get lost. The inside of the bumpers should be finished in a light beige paint (Mercedes-Benz have a paint colour for this). It is a good idea to clear wax the light beige paint and bolts to avoid corrosion.
Air suspension valves
Many people with these cars find that they start to sink down over night or over a couple of days, in other words there is a leak somewhere in the air suspension system. There are many different joints and valves, which cause a leak, and it is often best to use foam leak detector to find the leak before purchasing any valves or often-other expensive spare parts. It is always best to check that all four air bellows are ok. Another thing to bear in mind is that people think that they have a leak from the bellows when in fact water has worked itself in-between the face of the bellows and the steel air chamber. This often causes rust, which in turn means that the mating face of the bellows does not sit tightly on the air chamber. Another thing that can cause air leaks is where past owners have taken a valve or pipe off and not replaced the ‘o’ ring inside the joint. On most of the air system, a standard o-ring is used but on some parts a flat faced o-ring is used. Obviously, make sure you replace with the correct type. Whenever you take a joint apart always, replace the o-ring.
I replaced all my original steel air pipes with copper nickel pipes. I know this is not original but the obvious advantage is that they will not corrode. Having all these made up, bent to exactly the same shape as the steel ones was quite difficult and time consuming. However, they do look good, and are corrosion free.
The original air pipes were sprayed with a dark green paint. This green is the same green finish as the brake pipes. I decided not to spray this green paint on the air pipes. I was concerned that this paint would eventually start to come away from the copper nickel pipes from engine bay cleaning and lack of adhesion over time and thought this would look untidy. You can see an image of the engine bay below with the air pipes fitted. As a matter of interest apart from the air pipes, the only other thing that is not original on my car is the PerTronix unit. This is fitted to vastly improve the ignition, as in no more points, condenser or adjusting of dwell angles with the original two points set up.
Fuel injection pumps
When restoring the car the injection pump will need to be overhauled and re set. If you need to have the fuel injection pump reconditioned or re set, it is only necessary to remove the near side air tube (R/H drive) in order to take the injection pump out.
Once your pump is re fitted you will in most cases need to have it adjusted to suit your engine. This involves unscrewing the large nut at the back of the pump with the knurled collar sticking out of it. The knurled collar is for the mixture adjustment when first starting the engine, in other words if the engine will not idle, when the pump is re fitted then the knurled collar will have to turned a click at a time, clockwise standing behind the pump. DO NOT EVER TURN THE KNURLED COLLAR WITH THE ENGINE RUNNING, ALL CLICKS WITH THE KNURLED ADJUSTMENT COLLAR MUST BE DONE WITH THE ENGINE STATIONARY.
The back axles on these cars were fairly complicated for their day. You often hear how Mercedes-Benz 6.3 axles, have been repaired. This main reason for this happening is that some owners cannot resist the temptation to put there foot hard down from a standing start and of course with 1960’s 1970’s technology without modern day traction control you run the risk of spinning the wheels and or stripping some teeth inside the differential, and in some cases snapped half shafts. My own Mercedes 6.3 has had the axle out three times for repair. I hasten to add the last time it was taken out it was for a complete overhaul. So in other words do not put your foot down hard from a standing start, wait for the car to be travelling first.
Here are some main points for the axle. Although the following jobs I have listed below can be done with the axle in place although it is often easier to take it out for better access, especially if you are intending to replace most of the rubbers and anti dive bearings. If taking the axle out and apart, it is obviously best to replace all the oil and grease seals as well as bearings if the bearings are a number of years old and showing signs of wear.
The anti dive bearings are the plastic bearings which are located at the end of the axle next to the wheels. There are four large Allen key bolts per bearing. Make sure these are greased well as part of regular maintenance. These plastic bearings often wear out as they are not greased often enough through the grease nipples located on the bearing cases. The two large rubber bands each side of the bearing cases stop the grease from escaping and the ingress of dirt into the plastic bearings. These rubber bands often perish and allow dirt to get in and grease to escape easily. The anti dive bearings and the rubber bands, can be replaced with the axle in the car, after removing all the brake assembly. With the brake assembly off it will allow room to get to the Allen bolts, however these are often rusted in and often require heat to loosen them.
The large rubber bellows which is held on with the two jubilee clips can again be replaced with the axle in position, and often many people use the split bellows that can be glued to avoid having to strip one side of the axle. The adjustment bar from the chassis to the differential should obviously be adjusted correctly, and details of this are in the workshop/service manual. This bar has large rubbers which over the years go hard and perish and should be replaced. This rubber is replaceable without taking the axle out of the car. The rubbers on the swinging arms should also be checked for signs of wear. Worn rubbers can throw the geometry of the axle out. The anti roll bar rubbers should also be checked for signs of wear.