3-Series (E46, E90)Chat relating to the BMW 3-Series from 1999 to Current. Models include: BMW 316i, BMW 318i, BMW 318Ci, BMW 320i, BMW 323i, BMW 325i, BMW 330i, BMW 328 Ci, BMW 328i, BMW 325i/xi, BMW 330Ci, BMW 320d, BMW 330d, BMW 335d.
The previous owner replaced the engine in my 2000 323i because it was cracked after running hot. The "new engine" was said to have 84000 miles on it. Hoses were replaced. After installation the cooling system was flushed a couple of times. This was just before I got my beamer about a month ago. I just discovered that there is still a lot of oil in the form of brown sludge in there. Much of it floats on top in the filler neck of the expansion tank and also clinging to its walls. I have removed some of this stuff by adding coolant to make the sludge float up so that I can siphon it out.
The question is:Can that oil cause any harm. It is probably clinging to the hoses even after the flushes and is inside the expansion tank but I am thinking of replacing the tank as recommended in other posts. Maybe also the water pump.
I do not have any problem of over-heating. Never over the needle straight up.
I do not think the oil comes from the "new" engine. It runs great and the oil looked normal at a recent oil-change.
You need to get that system flushed again. You can do it yourself by draining all the coolant then filling it back up, drain, fill, drain, fill. Do this until all the water coming out of the car is clear. Then fill it half way with distilled water and half way with coolant. Run the car for a few days and hope it stays clean. If it doesn't, you may have a head gasket issue.
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