I'm currently looking at an '84 300SD being sold privately. The car is immaculate, and seems a good buy, but having owned a '76 300D and lived with it through a cold Saskatchewan winter (down to -50) I'm wondering if there is anything I should know about the 300SD that might deter me. Are there any major problems anyone knows of that occur with this model? So far I've found nothing but good about it, but in my experience, there has to be at least one thing wrong with every car. Thanks for any help.
If in doubt about the engine have its compression tested by a M-B shop. That will prove its condition - good or bad.
These SDs are among the best; the engine is tough and among the most reliable diesels. Their valves ought to be adjusted before winter and perhaps you should consider installing new glow plugs due to the extreme cold. A block heater is available; it installs above the starter - if the old plug can be removed.
In bitter cold preglow it two or three times before cranking the engine.
I bought an '84 300SD privately last fall and I love it. It's my favourite car. I won't drive it in the winter, so I can't comment on how well she'll start in Sask on a February morning, but I would expect the experience to be similar to your old 300D.
I'm not a mechanic, but I find things reasonably simple and easy to get at, under the hood of the 300SD. I ran across a website,
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that sell a variety of guidebooks for maintaining these cars as well as specialized tools and parts. Among other things, I purchased a book on how to tune your diesel engine and a pair of wrenches for adjusting the valves. It turned out to be an easy and rewarding job.
It's been said many times on this forum that if you start with a good car, you're laughing. If the car is a fixer-upper--it's a money pit. Perhaps the best thing to do is to assess (or have a competent person assess) the condition of the car. In the case of my car, the A/C leaked all the refrigerant, the cruise control is flaky and the MB dealer told me there was some free play in the differential.
In terms of work done to the car (in the 10 months I've owned it and
6,000 km I've put on it), I've set the valves, run a can of "diesel purge" through the fuel injectors, changed all the fuses (in case the original ones were corroded) and changed the oil. It gets a reliable
30 mpg in mixed driving, highway cruising at 120 km/hr. Someday, I'll have the A/C investigated and find out more about the differential - perhaps it can be shimmed.
I hope this helps, or at least gives you something to compare.
You definitely need the engine heater... like everyone said... have it checked out before you buy it... Once everything is okay, then have fun... W126 is very reliable car and very easy to fix. I owned one myself...
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