Problem spots on an 86 300e are bad valve guide seals (oil smoke on starting, excess oil consumption), worn timing chain, leaking head gasket, leaking top chain cover, and rear suspension links. You will need new flex disks every 60,000 miles or so as well. ACC can be a problem, but acutally less so than for the W123 chassis (cheaper to fix most times), except for the evaporator.

The evaporator can be a deal buster, it's about $2000 to replace (requires about 16 hr labor!), so if the AC doesn't work, take a pass or a big reduction in price. If it works OK and HAS NOT BEEN COVERTED TO R134a, take the car. If it's been converted, check to see if the evaporator has been replaced. If it has, the car will be fine. If not, it can go at any time.

Check for excess noise in the rear and for a 'loose" rear end on turns. If these conditions exist, you will have to replace some of the rear suspension links (not terribly expensive or difficult) and probably rear subframe and differential mounts. Very common on these cars by this age, but not a deal breaker unless completely shot, in which case I would not drive the car until replaced, they get VERY unstable on wet or icy roads.

Everything can be replaced at reasonable cost on these cars, so unless there is something seriously wrong (horrible oil consumption for instance), they are a good buy. A bit more performance than is good for a new driver, but very safe and predictable. Check for signs of oil leaking past the filler cap if it has a history of oil consumption, too -- the seal goes bad and a new one is a couple bucks!

Take it to a good independent shop and do a Pre Purchanse Inspection, they can tell you what, if anything, is wrong with it. Most likely, since the owners are likely the first ones, it has been maintained well, but needs things like AC work, suspension links, etc all at once. The mechanic can tell you!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!