Arguably Mercedes air conditioning systems have left much to be desired. One can argue that with the moderate summer climate of Germany and with the engineers focused on quality, performance, and safety, the HVAC systems may have been overlooked.

     The first Mercedes imported to the U.S. in the 1960's did not have air conditioning, and if you did wanted it, it was an afterthought. This included a hang-down inside unit and an almost home-made engine bracket to accommodate the inefficient York compressor. No auxiliary fan to cool the condenser was available until the early 1970's. Early AC and heat controls were strictly manually controlled with a blower speed control switch and a switch for temperature adjustment. A lever would control the direction of air flow, i.e.,whether warm air would go to either your feet or the windscreen. Manual controls are okay for most as long as the desired effect is realized. Heating was okay, but air conditioning left a lot to be desired.

      As the U.S. became more important to Mercedes sales, MB USA needed to respond to the demands for climate control systems for the U.S. market. The first "climate control" system for Mercedes debuted in 1976 in the S class 116 chassis 450SE, SEL and the 280S. The fact that this system was only used in the U.S. market provides evidence that the engineering strength for climate control systems by Mercedes left a lot to be desired. As a result, the CC system appeared as a convoluted system which was expensive and unreliable and this continued through 1981. In 1982 the climate control system was completely changed to a much more reliable and inexpensive system.

     One would think that the heart and soul of any cooling system would be the compressor but I strongly believe that for a Mercedes owner, the evaporator would be the most important. The evaporator is the device inside the dash which gets cold and provides the cooling inside the car. There are no moving parts to break, just a piece of metal about the size of a loaf of bread, with small tubes and fins to help dissipate the cold provided by the freon.

     The evaporators of most Mercedes through the 1980's were made of brass and copper and very seldom failed. Automobile manufacturers are always faced with government mandates to improve fuel economy, which means weight is always a consideration, and the durable copper based evaporator was replaced with aluminum as the base material. Unbelievably, the model which suffered the most from defective evaporators was the high line S Class models, of which many were priced above $70,000. This evaporator replacement is very expensive (about 25 hours of labor) and with about $800 in parts, at a dealer it would total well over $3000.

     With this in mind, what percentage of these evaporators would fail within 10 years? Unbelievably, it is close to 100%. Why would this part, a part that is so important and costly to replace, be so poorly designed?

     So what do we take away from this blog/article. If you are purchasing a W140 chassis car, you must check the evaporator for leaks. The fact that the AC is operational is not enough. (It may be a slow leak.) When you do a pre-purchase inspection, make sure you check the condensate tubes for dye which is from the refrigerant oil. This is always a tell tale sign of a defective evaporator.

     Good luck and make sure you do your pre-purchase inspection due diligence.

   

     The decade of the 1980's dawned with numerous challenges in the worldwide automotive industries. Unique challenges such as emissions, fuel economy, and safety presented problems to all makers of autos in the early 1980's - changes that auto corporations were not prepared to address.

     Because of catalytic converters, air pumps, EGR valves, and detuning engines, the U. S. Mercedes performance woefully lagged that of its European cousin. In 1981 the 3.8 litre V-8 engine debuted in the U. S., and they were installed in the 380SL and the 380SEL models. The new 3.8 litre engine was presented with an all aluminum block to replace the cast iron block of the 4.5 litre engine. The rest of the design was basically the same: overhead cams, CIS fuel injection with Lambda, which includes an oxygen sensor to help with fuel trim. The one glaring difference was the single row timing chain. The Mercedes European counterpart 3.8 litre engines retained the double row chain and gears from the 4.5 litre engines and the only reason for the single row chain appears to be weight related. But how much weight? Maybe 2 lbs for a chain, 2 cam gears, an intermediate gear, and a gear on the camshaft.

     The result of this application was somewhat immediate, as far as the failure of the single row chain. Mercedes blamed this on "poor maintenance," and did convert some to the double row chains for its "good" customers. Making the transition today to the double row set up is expensive ($3000) because the timing cover needs to come off and not only does the chain need to be replaced, but the cam gears, the idler, and the crank gear, and possibly some of the rails. The single row timing chain continued in the U.S. through 1983. In 1984 the single row chain was replaced with the double row chain and double row gears.

     Today, most of the conversions, especially on the 380SL, have been performed, but occasionally a single row chain does appear. If I were presented with a single row chain 380SL, I would recommend that the chain be replaced every 25,000 miles (about $300) and that the oil be changed every 3500 miles.

     With this being said, I still cannot find the reason Mercedes Benz would use the single row chain in 1981. From a quality performance engineering and financial point of view, it makes no sense. If any of our readers have any input, it would be appreciated to solve this mystery.

FUEL CONTAMINATION ALERT Owners of gasoline fuel injected Mercedes from 1976 through 1992 should be aware of fuel related issues which could be dangerous to your car's health, and to your financial health. Basically, the fuel distributor, which meters the fuel to each injector, will go bad for two reasons: 1.) Many customers are letting the cars remain idle for 6 months or more (for whatever reason) and the fuel degrades and compromises the inner diaphragm and seals. 2.) The quality of the fuel which includes a 10% blend of ethanol is not compatible for the K-Jectronic and the KE-Jetronic systems. This means that the owners of these vehicles must use an additive such as Stabil, or any comparable fuel additive, on a regular basis.

MERCEDES' 10 GREATEST ENGINEERING BLUNDERS

Dear Readers,

Over the next 10 weeks, we will discuss on a weekly basis some of the greatest mistakes made by Mercedes on operating and mechanical systems. These blunders are subjective and a matter of interpretation. I know there are those of you who may disagree and certainly have your own list. I would certainly welcome your input when you disagree with me.

The first blunder on the list, most readers will agree with, but those following are subject to interpretation. The word Mercedes in synonymous with design engineering, innovation, and perfection, so how could blunders ever be associated with this marque? Post WWII Mercedes had in its employ some of the greatest minds and engineers of the time: scientists and engineers who were responsible for WWII weapons such as the Tiger Tank, the ME262, the V-2 rocket, and other advanced weapons of design and destruction. After the war, many of these geniuses were to be employed by Mercedes when their production started again in 1947.

One of the first strategies used by Mercedes was to design an automobile which would make the Mercedes racing team competitive. Not only was Mercedes competitive, it dominated in Gran Prix racing in the 1950's. With this foundation, Mercedes was to epitomize automotive engineering for decades to come. With this background, it is a true mystery to determine the genesis of these forthcoming mistakes.

#1. THE INFAMOUS MERCEDES BENZ WIRING HARNESS

The defective harnesses were limited to certain years (1992 - 1996), and certain models. The 1992 and 1993 190E were not affected, nor was the 1992 300E. The models most prone to these defective harnesses were the 124 chassis 1993 - 1995, the R129 (300 SL, 500/600 SL, SL 320, S4 500 from 1992 through 1995. The W140 chassis (300 SE, 400 SE. And 400 SEL, 500 SEL and 600 SEL from 1992 through 1995). The W202 chassis (C 220 and C 280, 1994 and 1995) was also affected.

The decision by MB to use an eco-friendly coating for their wiring is relatively mind boggling. So are we to presume that MB made the wiring so that it would degrade when the cars were in landfills? Cars do not go to landfills. They are recycled. These coatings insulate copper, which, at this writing, is about $3/lb. Every MB manufactured 1992 - 1995 had engine and transmission wiring harnesses that would go bad - not 75% or 90% of the time, but 100%. Period. Mercedes knew about this issue within the first 2 years, but did not do the right thing and recall these cars and replace the harnesses? Of course not.

This problem occurred throughout the entire MB lineup: C, E, S, and SL classes. If you have a Mercedes of the 1992 - 1995 years with an original MB harness on your car, it is bad. Not only is the engine and transmission harness bad, but also the length of wiring to the throttle actuator, which means this very expensive part is defective - not maybe, but the chance of these harnesses being bad are 100%. So we have a 94E Class that from original needs a wiring harness, a transmission harness, and a throttle actuator. What happens inside these harnesses is that the insulation deteriorates, the wires touch each other and may damage the throttle actuator control unit and also the ECM. I'm sure the Mercedes bean counters conferenced with the engineers and decided that to financially recall all of the MB's made from 1993 - 1995 would be devastating to the bottom line.

If you are buying one of these fore-mentioned vehicles, you must have these harnesses inspected. The engine harness can be inspected easily by opening the hood, but the transmission or alternator harness is inspected by putting the vehicle on a lift. The other harness to be inspected is the harness for the electronic throttle actuator. To inspect this harness, a small slit with a box knife will expose the wiring. If you have a throttle actuator of the 92 - 95 years, the degraded insulation will expose copper wires. When this happens, the exposed wires will touch and possibly short the control unit for the throttle actuator. This control unit is called an E-Gas unit. We still see models of this vintage that have the original wiring harnesses, so if you are considering the purchase of one of these cars, make sure you have it inspected. New engine harnesses run from $800 - $1600, transmission harnesses are $250 to $550, and throttle actuators must be rebuilt because new ones are so expensive. Once again, if you are considering purchasing one of these cars, please pay a qualified technician to inspect these components.

2.) The Mercedes Single Row Timing Chain Mystery

Truly, I know there is an individual who knows why this single row timing chain was installed on all Mercedes V-8 engines which came to this country from 1981 - 1983. The cars we are talking about are not its lower end models, but the 380SL, 380SEL, 380SEC, and 500SEL.

In 1981, the model line-up for MB of North America included the 240D (4 cylinder), the 300D (5 cylinder), 300SD (5 cylinder turbo charged), the 280E, CE (6 cylinder gas), and of course the 380SL, SEL, SEC (all 8 cylinder gas). All of these models had double row timing chains with the exception of the 3.8 liter V-8's which had the single row chains. This engine was the 116960 for the U.S. market, while the European and other markets had 3.8 liter engines with double row chains!!!

So why? The double row chains would require additional parts such as: double row cam gears, double row idler gear, and a double row gear on the crankshaft. At the time of assembly (of the engine), the addition of a double row chain and its auxiliary components may have added $25 to the total cost. I can just imagine a Mercedes of Germany internal memo between the engineering, marketing, administrative, and finance departments that may go like this: "We need to **##!! the Americans, they are making too many demands - air conditioning, power windows, etc., and soon they may even want cup holders - so let's put in a single row chain in the most expensive sedans and coupes which will probably last through the warranty period, and we can make big bucks when the chains fail! Also, in a few years, Herr Dieter has plans to make inferior wiring harnesses, which we have also designed to fail once the warranty period has expired. We will take our revenge on the Americans for helping the British and the French!"

The previous, of course, is a ridiculous statement, but it makes almost as much sense as putting a single row chain in these fore-mentioned cars. I truly don't believe this was an engineering decision, because Mercedes has always over-engineered. Is this a bean counter issue? Risk and return I don't believe, there is not enough return to make such a decision. I don't think this is a marketing decision as less is not more. So this leaves us with something else; I would surely welcome others' input.

When posing the question, "Is your car a 4-matic or rear wheel drive?" many customers do not know! The distribution of 4-matics was, for the most part, in northern climates for obvious reasons, but 2nd generation owners acquire 4-matics through auction and the lease system in other parts of the country where 4 wheel drive vehicles are not in great demand for commuter usage.

For those readers contemplating the purchase of a second generation 4-matic car, the advantages always outweigh all other factors except one. Plainly and simply, operating a 4-wheel drive vehicle costs significantly more, especially when these cars have attained the 100,000 mileS mark.

The 4-matic provides better handling and better traction - handling which cannot be attained by the rear wheel drive model. However, this comes at a price: lower fuel economy as well as requiring more operation parts, such as additional drive shaft, differential, axles, and tire consumption. Overall, for the average Atlanta driver, I would opt for the rear wheel drive vehicle.

As seen by a member of the Baby Boom generation, no sports car satisfied the needs of the status-seeking individual more than the R107 Chassis Mercedes. This car's production run was from 1971 through 1989. During this period, the basic formula to make this car desirable did not change: the hood, grille, fenders, doors, deck lid, headlights, taillights, seat, and body trim from a 1971 model were the same as on a 1989 model.

The basic formula of great styling, V-8 engine (U. S. market), independent suspension, automatic transmission, removable hardtop, and mechanical soft top did not change. None of the components that went into the car and into subsequent models were designed specifically for the 107 chassis. The parts that went into the 107 chassis all came from earlier model Mercedes.

The first model planned to be marketed in the U. S. was the 350SL. However, because of U. S. emission constraints on the 3.5 engine, it was replaced by the 4.5 litre engine. 1972 and 1973 models were basically the same: V-8's with electronic fuel injection coupled with a 3-speed automatic transmission that would power this stylish gentleman's luxury sports car. (The phrase sports car was meant to be used in the styling sense, rather than pertaining to performance.)

The interior of these models was designed ergonomically in the true Teutonic fashion, with electric windows (in most cases), manual climate control, comfortable adjustable seating, topped off with the well designed, no nonsense, easy to use convertible top. Of course, this U. S. version would come with an additional "hard top" for winter use. However, many owners in the Southern climates would only occasionally, if ever, use the hard top.

The 1974 model was basically the same as its predecessors, except for a couple of "improvements." Actually, these were not improvements, but modifications resulting from Big Brother mandating changes. The first and most obvious was the legislation requiring that bumpers withstand a 5 mph collision without damage. The sleek and elegantly profiled bumper was replaced with an obnoxious, gaudy, and heavy device which featured two large shocks and protruding rubber bumper ends. Of course the rest of the world did not suffer from this styling fiasco. The other major change resulted from the growth of pollution in California. Mercedes had to meet the EPA restrictions in all 50 states (including California) so the resulting emissions had to meet the California requirements. This resulted in Mercedes adding catalytic converters to their cars. The result for the SL was that the catalyst was placed under the exhaust manifold. The increased heat from these ill-conceived devices played havoc with engine management and run-ability. This engineering concept continued until 1977, when the catalysts were moved from underneath the car to about where the driver's position is.

The next major change occurred in 1976 with the implementation of the CIS (continuous injection system). This fuel delivery system was more reliable and continued in modified forms through 1989.

In 1978, there were no mechanical or styling changes, but a new climate control system was introduced. This system was "borrowed" from Chrysler and was problematic to say the least.

The last year of the 450SL was 1980, and this is a model to avoid because of extra emission requirements and the continuation of the Chrysler AC system.

The 380SL was made from 1981 - 1985. In the years 1981 - 1983, MB engineers installed a single row timing chain, which MBNA agreed to change as warranty. In 1982 a much better and more reliable climate control system was added and remained unchanged through 1989.

Over the last 10 years and with with synthetic oil becoming a main stream product, service intervals have certainly changed. Many posts and articles that I read advocate extending the oil change intervals upward to 20k miles.

However, every different make and model, as well as each individual's driving habits, affect service intervals, and I would rather err on the side of caution as opposed to some variable dictated by monitors and oil tests, possibly conducted on some newer MB models. The Benz Store's recommendation for oil change intervals for model 2000 and newer:

under 125,000 miles: 7,500 – 10,000 miles

over 125,000 miles: every 7,500 miles

Most of the expensive repairs that we do are transmission related. Most people will religiously change their oil, thinking that they are servicing their cars.

Personally, I would recommend changing transmission fluid just as often as engine oil but I know this gets expensive, especially on the post 2007 cars. Transmission services need to be performed when the car is cold and the tech must have access to the Star diagnostic system.

Replacing a transmission on the 2007 and newer cars is an expensive ($5000) financial nightmare. So it is critical that transmissions be serviced. Intervals should not exceed 35,000 miles. I know this suggests overkill, but I cannot stress this more emphatically. This service costs roughly $300, but if you own one of these cars with a 722.9 transmission (2006) and newer you have to do this!

On the 2006 Mercedes and older, I would change fluids every 30,000 miles. In between these 30,000 mile services, at 15,000 miles, fluid only would be changed. I know there are some individuals who are rolling their eyes, but in my immediate family there are currently 3 cars with an excess of 300,000 miles, each with the original transmission and engine, and they last because of religious fluid and filter changes. In 35 years of owning various Mercedes, I have never had a transmission or engine failure under 300,000 miles.

Also, coolant should be changed every 2 years. This is so important on older cars because they have developed leaks and people will refill with just water, creating an imbalance in the 50/50 mixture. This will affect everything including the water pump, radiator, thermostat, hoses, etc. The estimated cost is $100.

Brake fluid should be changed every 2 years, estimated cost is $100.

Change the air and cabin filter every 12,000 miles, the fuel filter every 50,000 miles.

The high end models, such as the S, SL, CL, CLS, do have systems (airmatic, ABC-active body control, top operating systems, closing assist, pneumatic locking, and others, which have no preventive maintenance. However, if you want one of the above-mentioned cars, the cost of ownership can be mitigated by due diligence. If possible, buy from a first generation owner, who bought, not leased. Get all previous repair orders – obviously you want a nice dossier of repairs. And finally, get a comprehensive pre-purchase inspection. Finding a car that meets these criteria will be difficult, but you can reduce your time and effort by talking to the individual before you visit the prospective purchase. Be specific in your questions concerning service and repairs. Finally, find a good independent mechanic and put your trust in him. Trust this mechanic until he (or she) gives you a reason not to trust. A good technician will explain to you in detail what he is going to do.

In the early 1980's, a thriving grey market existed for the importation of foreign cars. There are a variety of reasons for this market, but first we have to define "grey market". The grey market is a method of distribution other than through the manufacturers channels.  Normally, vehicles brought into the U.S. have to comply with those standards set forth by the E.P.A. and the D.O.T. However, a law, or provision, was passed in consideration of military personnel stationed abroad. This law allowed those individuals to buy a vehicle while stationed abroad and then bring it to the U.S. once their tour was completed. This provision did not, however, specify that the individual needed to be military. In other words, any U.S. Citizen would have a one-time E.P.A. exemption. However, the individual did have to meet the D.O.T. requirements. This really opened up a Pandora's Box to abuses in the process by which cars were brought in, as well as to the D.O.T. certification process. Abuses prevailed as to the individuals who brought the cars in, in the sense that importers would import cars in the name of friends, family members, and whomever else had an existing E.P.A. exemption. The grey market existed for Mercedes for a variety of reasons, but I believe the foremost reason was financial. One could simply buy a European spec Mercedes and pay for shipping and federalization (remember, the E.P.A. specs did not have to be met) at a considerable discount to what one could buy a Mercedes with similar specs off the showroom floor in the U.S. There were pros and cons to buying a Euro spec Mercedes. In 1975, Mercedes, as well as other U.S. auto manufacturers, started an aggressive emission campaign in the U.S. that did not exist in Germany. U.S. versions were detuned and smothered with emission requirements - which greatly reduced the performance of the U.S. version Mercedes sold through the dealership network in the U.S. The difference in performance in the European spec MB and the U.S. spec MB was the difference in night and day. We had both a price and performance difference, which was enough incentive to enter the grey market. O.K., the pros were performance and price, but the cons were considerable. U.S. spec Mercedes distributed through MBNA would generally have all of the creature comforts such as climate controls, electric seats, power windows, cruise control, electric sunroof, central locks, and more. Most people, however, purchased used Mercedes that would have only a fraction of the components the U.S. Mercedes would have. For example, a 1979 450SEL would have an automatic transmission but no sunroof, electric windows, air conditioning or cruise control, cloth seats instead of leather seats, and so on. Many times, a German Mercedes would fail the German Federal Inspection but was sold to an unsuspecting U.S. client. German taxi cabs with over 300,000 miles were also sold through the grey market process. Once the grey market cars reached the U.S., the cars had to meet the Department of Transportation requirements to become certified for road use in the U.S. This check list included: 1.) Strengthening the doors, to protect from a side impact, with a steel bar which ran the length of the door. The cars Mercedes exported to the U.S. came with this heavy duty bar, the European versions did not. 2.) The bumpers were to be strengthened to meet the 5mph crash requirement that was federally mandated. The importer could replace the Euro bumpers with U.S. bumpers (no one did this - it was too expensive!) or strengthen the bumpers by welding an additional iron support on them. 3.) The headlights needed to be exchanged from the vastly superior halogen lights to the sealed-beam set up mandated by the DOT. 4.) The tail lights needed to be changed so that a side marker light was included and this light needed to be red. 5.) The speedometer had to be converted from kilometers per hour to miles per hour. 6.) Warning buzzers, such as seat belt, lights on, key related, needed to be altered to comply with DOT standards. Remember, no EPA requirements needed to be met on the European versions. This meant that catalytic converters, egr valves or secondary air injection systems were not needed. This, in turn, meant that the European version would "haul ass" and the U.S. version could not get out of its own way! As with any government mandated and run system, abuses and loopholes quickly arose. Originally, all modifications and repairs needed to be inspected, but as the importation of grey market automobiles escalated, the bureaucracy became bloated and began inspecting cars from photos and this included the checklist of modifications that were needed to be completed in compliance. Importers and shops that handled this process for the individual, for a fee, would keep one book of pictures and items completed per model and certify the cars, with little, if any, of the work actually being done. Some import shops would take pictures of U.S. headlights in the car, and then reinstall the European lights. The reinforcement bar in the door, in many instances became an expandable clothing hanger mounted in the door. Like all good things, the grey market passed on for various reasons: 1. The Feds eventually caught on and made the inspections stricter. 2. The dollar/mark exchange rate turned so the the dollar was worth less vis-a-vis the mark. 3. Mercedes began to develop a "world car" that would have more U.S. emissions (the Black Forest in Bavaria was dying) and the difference in performance was not as great. 4. Insurance companies found that to repair clients' cars was expensive because of the difference in parts and would refuse to insure grey market cars. Today, we do not see many grey market cars because the majority were of the 1980-1985 years. But if I could find a rust free car that still operated, I would seriously consider buying it.

For me, the selection of a model has always been influenced by the cost of operation, the cost of maintenance, the cost of repair, depreciation, and taxes. Of course, if everybody followed my criteria this would be a very boring world.

The more creature comforts, the more gadgets, combined with technology and styling, are making the Mercedes very expensive to own and operate.

The following is an evaluation of the various classes of Mercedes. These thoughts are a result of 35 years of experience and repair of Mercedes. As with any subjective evaluation, one may have a different point of view and we certainly welcome any input into our evaluation.

I know you have plenty of friends, but this is one of a different nature. If you own a car that is out of warranty, you have to establish a relationship with a fair, honest, competent, and efficient independent repair facility. That being said, finding one my be a tough task.

There are several ways to find a repair facility. Asking other Mercedes-Benz owners is one source, and online reviews is another (though not always reliable). But sometimes you just have to resort to trial and error. You will want to look for a tech or service writer who will communicate with you, giving you a fair estimate of repairs, and completing the repairs close to these estimates.

If you find such a facility, love, cherish, and let them know how much you appreciate the business, because they truly are a dying breed.

Ken