PeachParts Mercedes-Benz Forum - View Single Post - Considering purchase of a 1987 300D, what to look for?

Jeremy5848 · #5 07-21-2009, 11:10 PM

The '87 300D is a joy to drive. More powerful and better handling than the older W123 cars with their less-powerful OM617 engines, more fuel-efficient and aerodynamic, the '87 300D (W124, OM603) was the first "modern" Mercedes diesel. The body style was copied by almost everyone and still looks "new" today. A typical car will get 25 MPG around town and 30 MPG on the road. YMMV.

Mercedes started selling 124 gassers in Germany in 1985 and brought them to the USA in 1986. For 1987 the OM603 diesel engine was introduced. The engine came with an alloy head that was (and still is) more susceptible to cracking if the engine is overheated than are the older iron-head engines. Improvements were made to both the head and the head gasket and the later versions were sturdier but it is still wise to keep an eye on the coolant temp gauge and not "try to make it home" if it starts to climb above 110C or thereabouts.

The oldest head has a part number with a "14" in it, later models were "17" and "20" and the last one had a "22." I would not necessarily avoid a car with a #14 head but given a choice, take the later version. You might consider using as a bargaining tool the possession of a #14 head. My car has a #14 head and I have no problems with it. However, the cooling system is in good condition and I keep an eye on it.

I have never heard why Mercedes dropped the 603 engine after the 1987 model year. It may have been because of the head problems or because of tightening smog regulations. In about 1990 they came out with a version that had a 5-cylinder turbodiesel, the OM602. The last W124, in 1995, had the OM606 6-cylinder normally-aspirated engine. As the years passed, the W124 got more and more electronics. The earlier models are therefore simpler and easier to care for.

There are a number of things that are easy to overlook but very expensive to repair in this car. They are: cracked head or blown gasket, suspension (under the car, problems are easy to hide), climate control system (sellers always say "it just needs to be recharged"), sunroof (the W124 came with the first slide/tilt sunroof and there were some design problems). These items can amount to thousands of dollars. Each. The cruise control is another common failure point but is less expensive to repair. You can get a rebuilt "brain" for about $300.

On the other hand, there are parts of these systems that you can fix yourself. With your own labor and also saving money by buying from FastLane, you can fix some parts of the suspension and the climate control yourself. The sunroof is a bigger challenge, not a DIY job for most of us, but you can live without it. You can change the oil and the fuel filters and the glow plugs yourself. You can replace light bulbs and patch broken wires.

I am seeing many W124 gassers (300E) in the junkyards now. Since the body of the gassers is the same as the diesels, this means lots of inexpensive body, interior, and trim parts are available.

The W124 chassis has far more in the way of creature comforts than the older cars; this also means more to repair. The '87 300D has ABS and a driver's air bag. It has power seats (with driver's seat memory) and retractable rear headrests.

Some people are good at repairs, others avoid them like the plague. This is a personal choice that you will have to make for yourself. If you have to hire someone to do repairs for you and pay full list price for all the parts, you will quickly learn why we say that there is no such thing as a "cheap" Mercedes. You can save at least half by learning to do the work yourself.

The '87 300D has the 722.4 4-speed mechanical automatic transmission first introduced in the last W123 cars. It is a good transmission and is generally very reliable. Lifetime is usually 200,000 miles or more. It is about as expensive to overhaul as most other automatic transmissions and is not a DIY job for most of us.

Much more information is available here via the search function. Good luck with your shopping. Have a professional inspect anything you're seriously thinking of buying. A hundred bucks will save you thousands of dollars of grief (ask me how I know).

Jeremy