Advice on '87 300D

[warmblood58]

Found a nice low mile diesel for my gf, an '87 300d but do not know much about this generation of MB's as I drive early eighties 123 and 126 diesels. Anything I need to look out for? For a short time, I owned a '98 e300, amazing car but waaay too much technology so I sold quickly and made a few bucks -there was a "seat sensor" that required roughly 1,200 bucks to fix. Will I enjoy working on this car as much as my older MB's? Any weaknesses? Thanks!

[Jeremy5848]

There are many threads here on this specific subject. The search function is your best friend for a question like yours.

The W124 was the first "modern" mid-size Mercedes and as such lacks the "classic" look of the older cars that you are used to. OTOH, it has more conveniences and looks much newer than it really is -- the smooth design was copied by almost everyone. The OM603 engine is quieter, smoother, and more powerful than the OM617 while getting better fuel economy. The W124 chassis, while of almost identical wheelbase and overall length, has many improvements resulting in improved handling and smooth ride.

More goodies means, of course, more things to break and need repair. Fortunately, most things on the W124 are at least as reliable as the analogous parts on the W123. Note that a W124 can be very expensive to maintain if you have to pay someone to do maintenance for you. If you can do your own work, not so bad.

The OM603 engine (offered in the 1987 model only plus the 1986-87 SDL) was the first diesel Mercedes to have an alloy head and it is sensitive to being overheated. This is perhaps the one big negative difference between the OM603 and the OM617. A harmless loss of coolant accident in a 617 could result in a cracked head in a 603. The temptation to try to "make it home" must be avoided. Keeping the cooling system in good repair (radiator, water pump, hoses, correct coolant, etc.), while important in any engine, is more important in a 603. Early versions of the OM603 head (#14 especially) have a reputation for gasket failure but this does not always happen -- mine, for example, has been trouble-free. Later versions of the head (#17, #22, etc.) were redesigned to eliminate this risk.

Later W124s had the five-cylinder OM602 turbodiesel. Almost as powerful and boasting even better fuel economy, the OM602 was offered in the early 1990s. Its alloy head is similar to a late 603 head but can also be damaged through overheating.

The last W124 in 1995 got an early version of the OM606 engine with twin overhead cams but not turbocharged. This engine was carried over to the 1996-97 W210 cars and, as you know, was turbocharged in 1998-99.

In general, over the ten year span of the W124, the cars became more complex and more electronic. The 1987 300D Turbo has the advantage for me in that it is only slightly more complicated than a late W123 while being in many ways superior. I enjoy working on it as much as I did my '85 300D-T. YMMV.

As always, a car with complete service records is always better than one without and watch for rust in the usual places.

Jeremy

[warmblood58]

Thanks Jeremy! Good information! We have to get together in SR/or Napa soon and compare notes. Just replaced my injector nozzles in my '82 300sd and love the difference -Gus at Pacific Fuel Injection balanced and adjusted nozzles before I installed, love my 123 and 126 cars, hopefully I will enjoy working on my gf's 124 if she buys it.

[Jeremy5848]

We can meet for coffee some place mid-way and I can go over my '87 for you -- point out hings to watch for, etc.

Jeremy

[warmblood58]

Originally Posted by Jeremy5848

We can meet for coffee some place mid-way and I can go over my '87 for you -- point out hings to watch for, etc.

Jeremy

Great, I will most likely have Dave Ball, Apex Motorwerks check out car for me as he is an amazing guy (in Novato) At one point, I wanted to organize a clinic at his shop for Bay Area diesel folk as he knows how to adjust./diagnose our sometimes picky transmissions among other things -