1980 Mercedes-Benz 300-Series

Coupe

5.6L Mercedes-Benz M117 Normally Aspirated Gas V-8

Automatic

12315012005170

Clear

Diesel

1980 Mercedes-Benz 300CD5.6L M117 V-8NO RESERVE - BID TO WINThe Mercedes W123 coupe is a timeless, elegant car most commonly equipped with the legendary OM617 diesel engine. In 1992, the long-term third owner of this coupe had the original diesel engine and three-speed automatic transmission professionally swapped for a 4.2L Mercedes M116 gas V-8 backed by a four-speed 560SL automatic in an effort to create a car that Mercedes never did from the factory – a V-8 W123 coupe. When the first 4.2L engine dropped a valve in 1996, a 5.6L M117 from a 1989 R107 chassis 560SL was sourced and installed. Needless to say, this is an interesting car and one of the only W123 coupes around running a 5.6L Mercedes V-8. I have over $30k of maintenance and repair records on the car dating back to the late 1980’s and am happy to email a summary spreadsheet. The previous owner purchased the car in 1984. It appears that it has been a Texas car since at least 1982. History and Documentation of the Engine Swap In January 1992, the first V-8 swap was completed with a 4.2L M116. A shop in Dallas called European Precision Service (now closed) completed the work to the tune of $11,600. I have all of the records of the work done. Throughout 1992, the then-owner sorted the swap, adding a true dual exhaust with H-pipe and Flowmaster mufflers. The first 4.2L engine apparently dropped a valve in 1996, necessitating the replacement of the engine. A 5.6L M117.967 was installed in late 1996 along with a custom aluminum radiator. The M117 is a tall motor and required the use of a M116 oil pan and a low profile air filter assembly to fit properly. This engine box stock makes 170 horsepower and 380 lb-ft of torque, doubling the horsepower and tripling the torque of the original diesel. It’s quite a bit quicker than the original version. The receipts for the second engine swap totaled $8,500. All told, the previous owner spent over $20k on the engine swap(s) and attendant modifications to make it all work well. The replacement engine had 51,000 miles on it when it was installed. The chassis had 110,231 miles at the time of install and now shows 130,821. The previous owner claimed that the odometer stopped about a year ago at its current mileage reading of 130,821 when he mistakenly hit the trip odometer reset button while driving. The car has been driven very little in the past few years, and I have records to support the mileage being not too far off of the current odometer reading. Assume that the 5.6L engine has somewhere between 70-80k miles. This is not a backyard swap done with a small-block Chevy and a crowbar. The swap work was done by professionals, sorted by professionals, and has several years and miles now of working out the bugs. It’s a running, driving car. The engine runs a standard distributor and does not have the computer controls from the donor SL installed. It all works well. Specifications/Options Exterior color – Code 473 Champagne (champagnermetallic)Interior color – Code 237A “Nappa” Red LeatherSunroofElectronic locking rear differentialCruise controlBecker Europa II AM/FM stereo with power antenna Mechanical/Electrical Condition Engine/Transmission/Driveline​Starts easily and idles smoothly, however the starter occasionally hangs. Not sure what’s up there.Transmission shifts firmly.Rear end is quiet with no whine. CV boots are fair – older but not torn. Climate ControlBelt is off of the a/c compressor, but it and the clutch spin freely. The a/c system was fully rebuilt in 1995. A new compressor, expansion valve and drier were then installed in 2003 and the car has only been driven a few thousand miles since. I’d assume that it needs a full service, but at least many of the under-hood parts have seen limited use.The dreaded Chrysler-sourced ACC climate control module does not appear to work. I have not investigated much farther than checking fuses and seeing if there are any obvious wiring issues under the dash. Steering/Suspension/BrakesGoes down the road smoothly.No significant wear on any front end components, although the steering stabilizer seems like it is worn out.Plenty of brake pad all the way around. Car stops straight with no pull to either side.Good tires with plenty of tread – fronts match, rears match, but they don’t match each other.Nice set of 14”x6.5” bundt alloys from a W126. ElectricsThe sunroof is in-op. The electric motor runs, but the sunroof panel doesn’t move.Windows all go up and down, but the rears are a little slow in both directions.Dash lights are a bit finicky – the rheostat probably needs to be removed and cleaned.The original Becker Europa II stereo is in place, works well, and sounds good. Power antenna goes up and down.Lights all work. The car has a current Texas state safety inspection. Cosmetic Condition Paint/BodyThe car was repainted in 1998 in its original Champagne color. It was a budget glass-in repaint, but shows well with good shine. There are a few prep and masking issues, but the paint has good shine and presents very well.There is some rust forming in the windshield channel and cowl. That’s the worst part of the car. There is some random bubbling in the front quarters and a bit in the trunk. There is also a bit of corrosion on the inside of the trunk lid. I think it was stored outside for some period of time and the trunk gasket leaked. There is evidence of prior moisture issues, as the trunk is missing part of the lining and the Masonite floor is warped. The body is straight with no significant dents, dings or rock ships. All of the anodized trim is dull. Older Mercedes trim is quite difficult to polish properly, but there are kits available to polish it to new.The backlight has the common delamination on the lower edge that is creeping up the glass. All of the window glass is Sekurit and appears to be original. The windshield is an aftermarket replacement. InteriorThe red leather interior is unique and something you don’t see too often in a W123. It’s in excellent condition for the age, and only shows some cracks on the top of the rear seat back. The driver’s seat has some mild scuffs on the outside bolster, but no cracks, tears or other issues. The wood surround for the ACC is in the glove box as it doesn’t stay on.Some mild lacquer cracking on the console wood, but the veneers appear to be in good shape.A few thin cracks on the top of the dash.Headliner is in excellent condition.Carpets are in very good condition.The passenger side under dash panel and kick panel are in the trunk. They are in good condition but don’t fit well. I did not want to risk cracking the plastic by reinstalling. All-in-all, this is a unique car with a definite sleeper vibe. The diesel badging is intact and the car looks stock from the outside. Only a Mercedes W123 enthusiast would pick up on the fact that the mufflers hang a little lower than on a stock car. Firing it up and hearing the V-8 rumble through the Flowmasters will definitely have people scratching their heads. You can take it in a bunch of different directions – keep it as is and enjoy a stylish pillarless coupe with some grunt, build a highly unexpected drag car, lay it out and have a bonkers drift car to embarrass all of the backwards-hat-wearing Nissan 240SX drivers. Your call. It’s a cool vintage Mercedes in interesting period colors regardless of how you use it. I’m thinning out my collection/hoard of vintage Mercedes due to certain members of my household feeling as though I have too many cars. Bid to win, this is a no reserve auction and your winning bid buys the car. I’m happy to answer any questions to the best of my ability and take any additional detail pictures in order to help you make an informed purchasing decision. Good luck!