Buyers Guide - 1965-1972 108-109 Series: The New Generation 250, 280, and 300 Sedans

When Road & Track called the 108-109 Series "Merely the greatest sedan in the world", Mercedes Heritage recently referred to the cars as the perfect entry-level classic Mercedes

The 108-109 Series
The "New Generation" Sedans

A Brief Buyer's Guide to the 250, 280, and 300 Sedans and Their Engines

by Richard Simonds
with contributions from Mathieu J. Cama and Pierre Hedary
Photography by Bob Doerr and Larry Taylor

"Merely the greatest sedan in the world" said a Mercedes-Benz marketing brochure quoting Tom McCahill in Road & Track regarding the 300SEL 6.3 sedan.

The 250 sedan in the same brochure was called, "The near-perfect mating of suspension, brakes, powerplant and functional design makes it one of the most desirable 'sports sedans' in the world." Following up on the 110 series (finback sedans), the design included unibody construction with "safety zones" designed to crumple on impact, a padded dash, seat belts, headrests, recessed door handles, a collapsible steering column mounted behind the front axle instead of in front of it, and a rearview mirror that was spring-mounted to break away if struck. MercedesHeritage.com recently referred to the cars as: "The 108 chassis: the perfect entry level classic Mercedes."

Mercedes-Benz produced the 108/109 chassis from 1965 to 1972 with nearly 400,000 units shipped worldwide. With most models sharing the same wheelbase of 108.3 inches, the 108 series had coil spring suspension; the 109 series had air suspension. Offering several different engines over the production run, the sedans were available in 250, 300, and 280 versions, with the differences related to engine size. Long wheelbase versions of the 280s and 300s, with four more inches of rear legroom, were also produced, mostly for limousines and taxis. Today, the 108 and 109 series sedans could be called "The Forgotten Generation." Current books emphasize the coupes, cabriolets, and SLs and, with the exception of the 300SEL 6.3s, ignore these magnificent and practical sedans, making them much less expensive than other classic Mercedes automobiles and thus even better for the beginning classic car enthusiast.

Background

The 108/109 series was developed to bring a larger and more contemporary style to the lineup of Mercedes-Benz sedans. Visibility is very good. The styling is still quite pleasant and few people recognize the car as being a 40-year-old design.

The trunks were larger, the wheels were 14 inch (instead of 13 inch), the engines were more powerful, and the driver and passenger amenities were more in line with cars of the 1960s than previous generation Mercedes-Benz sedans. Four-wheel disc brakes were standard.  Air conditioning was mounted under the dash but was not known for being effective in weather over 85F. Seat belts were standard though with Kangol magnetic buckles that seem quirky by today's safety standards. 

Virtually all cars coming to the United States had automatic transmissions, although the 4-speed manual transmissions with column-mounted or floor-mounted shift was an option on all models except the 4.5 liter and 6.3 liter V-8s.  A 5-speed manual transmission with a floor-mounted shift lever was available on the 300SE, 300SEL 3.0 and 2.8, 250SE, 280SE, and 280SEL with the inline six-cylinder engines.

Total production worldwide of the various 108/109 models was 378,285 from 1965 to 1972. It seems they could be considered a success by that criterion alone. It also means that there is a potentially large pool from which to select a pristine example. Remember the adage, "Always buy the best example you can." Full restoration is always more costly than the ultimate value of these vehicles.

Reasons to Buy a 108/109

• Engineering and build quality was excellent.
• Safety features make them an exceptional family car for daily use.
• Styling is contemporary and classic at the same time.
• Able to comfortably haul five people and their “stuff” on trips.
• Parts (new, used, and remanufactured) are generally available for bodies, engines, drive trains, and so forth.
• Air suspension on the 109 series provides a supple ride with great handling and control.
• There were a lot of them built with a variety of engines so you have choices – many choices.

Reasons Not to Buy a 108/109

• Sedans often suffer from neglected servicing and components that need rebuilding or replacement.
• Bosch D-Jetronic fuel injection systems on 3.5 and 4.5 liter V-8 engines are expensive to repair or rebuild.
• Faulty steering boxes and automatic transmissions are expensive to replace.
• Fuel system components often need rebuilding or replacement because of damage from ethanol. They all require premium fuel!
• Automatic transmissions can shift very harshly unless properly serviced.
• Door lock systems and window cranks may need to be replaced or rebuilt. 

Checkpoints

1. Chassis - Although the factory touted its "heavy slathering of plasticized undercoating," rust is always a major issue with front frame rails and bumper supports because of safety.  In addition floor pans, fenders, door rocker panels, and door sills need to be checked. 
2. Engine - These have been just "old cars" for a long time, driven because they were cheap by people who might not have invested time and money in engine maintenance. Engine bearings, camshafts, and other moving parts can suffer from postponed oil changes. Have the engine checked out thoroughly by an experienced Mercedes mechanic with the proper equipment to avoid expensive surprises that can double or triple the price you pay for the car. Pay particular attention to the fuel system, as noted below, and in "The Nitty-gritty" on the next page.
3. Suspension - these cars have lubrication points throughout the suspension and lack of regular maintenance can allow the grease to solidify into concrete-like consistency causing damage to lower control arms, suspension links, kingpins, and dried-out bushings that need to be replaced.  The early cars had a hydraulic compensator on the rear suspension.  If it fails it can also damage axle boots.  Repair can cost ~$1,300.  Air suspension on all 109 models requires regular maintenance and the use of methanol antifreeze to avoid having water in the airlines.  Check for damage to the air valves, airlines, pump, and airbags.  A well-maintained air suspension should hold air without leaking and stay up for two weeks.  The 109 series with air suspension are: 300SEL; 300SEL 3.5; 300SEL 4.5; 300SEL 6.3.  Note: The 280SELs did not have air suspension.
4. Differential - Bearing noise and gear lash adjustments are the most likely culprits here. Bearings may need to be replaced.  The 6.3 models are vulnerable to differential wear and stripped pinion gears because of overly enthusiastic driving.  "But, dad, the 6.3 has so much torque!  I had to test its performance."
5. Interior - Heater blower motors are inaccessible and quite expensive to replace.  Heater control levers can be replaced fairly easily, although the underlying problem of poor access to lubricate the controls and cables is a problem for all M-Bs of this vintage. Power window switches may need to be rebuilt (see my article in The Star, July/August 2008, pp. 76-80).  M-B Tex is nearly indestructible, but back seat upholstery may dry out from sun exposure coming in the back window. Carpeting wears out although complete color-matched kits are available from several sources. The woodwork on the dash is not as finely finished as in other models and may need to be refinished or replaced.
6. Gearbox - Automatic transmissions are fairly durable but often need a rebuild kit for vacuum modulators. These are fairly basic mechanically operated units that are durable if serviced regularly.  For the column-shift, check the cable-driven shift indicator for adjustment or replacement and general wear in the shift linkages to the transmission.
7. Fuel System (carburetors / fuel injection) - Poorly maintained carburetors and fuel-injection system necessitate rebuilding although the basic components are quite durable and don't often need to be replaced.
8. Power Steering - Power steering pumps and reservoirs may need rebuilding and hoses replaced.
9. History - Get as much information as you can from the seller, including a history of maintenance as far back as you can get it. These vehicles are quite well-engineered and durable, but six-cylinder engines will probably need a rebuild around 200,000 miles while V-8 engines are probably good for 300,000 miles.

The Nitty-Gritty

Given the number of engine variations over the life of the 108/109 chassis, there are many points that could be made about the series. In this series, the bodies were for all practical purposes identical. So, the choices come down to engines, acceleration, fuel economy, the condition of the one you are looking at, and price. That said, here are a few observations.

The 300SEL 6.3 is the most desirable from a performance and collectability standpoint. But, the air suspension on the 109 chassis and the thirsty engine could sway a buyer toward another model. Next in line is the 280SE 4.5, 280SEL 4.5, and the European versions with the 3.5 engine (280SE and 280SEL both of which had very low production volume).

After these, the fuel-injected six-cylinder engines provided better performance and equal or slightly better fuel economy than the engines with carburetors. The Bosch D-Jetronic fuel injection on the 3.5 and 4.5-liter V-8 engines should be given special attention; your mechanic will need the Bosch D-Jet Factory test equipment to check the system properly. The risk in a poorly maintained or seldom driven vehicle is that rebuilding a fuel injection pump (approximately $2,500) and replacing injectors (about $300 each) is considerably higher than rebuilding a Zenith 35/40 INAT carburetor.

The Zenith 35/40 INAT carburetors can be warped, especially the upper housing, by over-tightening the bolts, causing air leaks and erratic operation. Rebuilds can cost about $60 each plus labor if the upper housing is not warped. The large compensating diaphragm may need to be replaced if it disintegrates from ethanol in contemporary gasoline and there is a brass vent valve in the exterior carburetor body that occasionally vibrates out and is lost. It, too, may need to be replaced in each carburetor. If maintaining your 250S or 280S in concours condition is not a concern, you can replace the troublesome Zenith 35/40 INAT carburetors with a Weber K 245-38 DGES set for ~$1,000 plus labor.

The Mercedes-Benz 4-speed automatic transmissions during this era always started in second gear, so acceleration is quite leisurely - especially on any upgrade. Moving the shift lever into the "2" position will engage first gear, providing stump-pulling torque and good acceleration off the line with a very firm shift into second. Be sure that your head restraint is in position because the shift from "1" to "2" can nearly roll your head into the back seat. Incidentally, the gear indicator on the dash can be simply adjusted from an access port under the dash to the right side of the steering column if the cable linkage is not broken.

Cooling systems and head gaskets on 2.8-liter six-cylinder engines should be inspected for coolant leakage and possible engine damage. Timing chains and guide rails should be inspected for wear-especially on V-8 engines.

The Kangol front seat belts can be replaced with a factory approved retractable belt assembly, Part #115 860 4285, available from the Mercedes-Benz Classic Center USA, Irvine, CA (866-622-5277, classicparts@mbusa.com, or www.MBClassicCenter.com). The rear seat lap belts can also be replaced to match the front ones if desired. (MBCA members always receive special pricing from the Classic Center.)

As with any classic Mercedes-Benz, a thorough pre-purchase inspection by a qualified technician is your best safety net.

Value Estimates

Values based upon Hagerty's Cars That Matter.
Low estimates are for cars that can be driven safely but may have issues that are too expensive to fix.
Medium values are for cars that could win local car shows.
High values are for exceptional cars that are rarely driven.

References

Mercedes-Benz Production Models Book: 1946 - 1995. Nitske, W. Robert.  Motorbooks International, Osceola, WI. 1995. ISBN 0-7603-0245-6

Illustrated Buyer's Guide: Mercedes-Benz, Second Edition. Barrett, Frank. Motorbooks International, Osceola, WI. 1998. ISBN 0-7603-0451-3

Hagerty's Cars That Matter: Edition 11. Kinney, David H. Published by Hagerty's Cars That Matter, Great Falls, VA. 2010. ISBN 978-1-61584-516-3

A Real-World Example

So why am I so passionate about the 108/109 series sedans? In essence, it is because they are still magnificently engineered, built with passenger safety construction, nicely styled, and very comfortable as touring cars. They had most modern amenities available, including air-conditioning (under-dash and quite effective on moderately warm days, not so much on really hot days), a nice-sized trunk, and an engine compartment that is accessible for the do-it-yourself owner. I remember falling in love with the styling, engineering, and safety features when I first saw them in the 1960s. In the interest of full disclosure, I also have a 1965 230SL (W113) that has many of the same styling and technical features. So, I own today what I could not own then on my teacher's salary.

At StarTech 2007 in Reston, Virginia, I saw a beautiful blue, 1969 280S with a "For Sale" sign and some datasheets on the windshield. After my wife, Laura saw it, and we took a test drive, we negotiated a price of $10,000. A few weeks after StarTech, I flew back to Lancaster, Pennsylvania, with a driving buddy to get the car and drive cross-country to the San Francisco Bay Area. Brave or foolish, we made the trip with no major incidents (although we discovered that the carburetors needed rebuilding and we could only manage 7 to 9 mpg). At one gas station, I could not get a full tank because the credit card limit for a gas purchase was $75. That said, however, we made the full cross-country trip in six comfortable days with all kinds of weather to test that all other systems would work. They did.

The next year was spent in finding lots of little items and a few bigger ones that needed to be repaired or replaced. We spent $20,000, far more than we expected, but we now have a beautiful car that Laura drives and enjoys because it came equipped with those key items she requires, including automatic transmission, power steering, power brakes, power windows, great visibility, classic styling and room for four more family members or friends.

So, our "Blau Belle" (that's German for Blue Belle) now sits proudly in our garage next to her sibling, the 1965 230SL. Blue Belle competed in the Concours d'Elegance at StarFest 2008 and received a second-in-class award among her Show Class peers. Earlier this year I drove from the San Francisco Bay Area to Phoenix, Arizona, so that we could use the car in our oldest grandson's wedding. We cruised along at 65-75 mph and averaged 16.76 mpg. At those speeds, the engine was running at 3400-4000 rpm, but with its "over-square" bore and stroke, the piston speeds were well within limits and we enjoyed the sweet hum of the engine in the background. The air-conditioning fan and radio easily overcome the engine sounds.

The bottom line: we have a car we can enjoy now just as we might have in 1969 and for many years to come. I know that I'm "upside down" financially, but the pleasure of having such a sweet ride overcomes it!   Richard Simonds

By the Numbers