OK, here's the deal. The engine in my '74 240D runs great. I've done work to it in terms of normal maintenance items (fuel filters, oil/filter change, replaced primer pump, fuel hoses, valve adjustment, new GPs, etc). It starts pretty well but when cold can be just a little rough and does have blue/grey smoke when idling cold which goes away when warm and hot. It always starts after just 1-2 revs after pre-glowing when cold and the same way when hot without any pre-glow needed.

I just did a warm/dry compression test "by the book" method and these are the results:

#1 24 bar
#2 24 bar
#3 24-25 bar
#4 22 bar

Spec is 22-24 bar with no more than 3 bar difference between two cylinders. Basically it passes the compression test fine, but I could probably have predicted that since it sounds super when it runs, smooth and the normal "sewing machine" sounds when running (I don't say it is quiet but what OM616 is).

It was running cool when I bought it due to a stuck thermostat so I replaced it and it now comes right up to 175± on the gauge and stays there when runnning. It was also nailing like mad when I got it but a set of rebuilt injectors took care of that 100%. Also, I checked the vacuum pump hose and it appears to be intact and not leaking oil through the line to the intake. Blowby is not bad, you can loosen the fill cap and it does not dance or even really lift, but if you remove it you will see a reasonable steam plume. Certainly not what I call excessive.

So, its only fault now is the blue/grey smoke and an appetite for motor oil that is puzzling (as the title says, one quart every 100-200 miles). Oh yeah, and it has no real leaks. I mean it will have a single drop or two on the floor after shutdown and sitting overnight, that's all and none while running.

I have no experience with faulty valve stem seals and am wondering from others here if it is possible that oil consumption at that rate could be caused simply by bad seals or do I need to look elsewhere? and if so where?

I also know from experience these early 616's do consume some more oil than the later ones for a variety of reasons, but I would expect the rate to be closer to a quart every 500-1000 miles on such an engine rather than 1quart /100-200 miles. I owned a 240D before that used a quart about every 300 miles and did so for years without a problem but this one is even worse than that!

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz