Yesterday I checked out an '87 300D that a local small dealer had gotten in, both for someone else on the forum and a friend down in TX.
Coolant tank had what appeared to be something black in it when viewed from the outside, along with the same color material splattered on the inside.
Pulled the cap off to check, and the cap came off in pieces, so old it had literally fallen apart. Looked inside the tank, it had what looked to be reddish brown slime inside it, and what appeared to be dirty brown oil floating on top. Some of the slime was coating the bottom part of the radiator cap.
Car has the original 14 head on it, 136K miles. While the radiator hose didn't have any pressure on it, the shape the radiator cap was in makes me wonder if any pressure could even build up in the system. Glad I didn't have time to drive it!
Engine did start right up, idled smooth and quiet, quieter than mine. But aside from a brand new vacuum pump and new fluid in the master cylinder reservoir, from the appearance of the engine bay this car has seen very little maintenance. Carfax doesn't pick up until '92 and 56K miles, been thru at least 3 owners since then.
There was also fresh black oil underneath on the drivers side, most likely from the oil filter I'd guess. Underbody panels were long since gone, some good rust starting in the rocker panels. guy is asking $5K for it.
The status of the cooling system tank threw a red flag for me, some major potential problems indicated with what I saw. That right there made me want to shy away from this vehicle.
Does this sound like a cracked head or leaking head gasket, or at the least, the potential buyer looking at some expensive rework right off the bat?