M50 engine R&R

This is a new thread from posting on May 2, to avoid confusion (for me!)...


First guess is the rings on #3 have failed, thus the oil. You didn't mention smoke from the exhaust or anything about coolant, so I can't be more specific. Either way, I'd remove the head. If the rings need replacing, it can be done on #3 without removing more than the head and oil pan (I've done it), i.e. the engine can stay in the car. This will allow for direct inspection of all the cylinders, walls, and the bottom of the head and valves. You'll be able to replace nearly anything you need to at this point. New: head gasket, head bolts, rings #3 (they come as a complete set and I might just do them all to be safe since it's open), valve cover gasket. Check the timing chain guides or belt and tensioner, intake-to-head gaskets if removed. Maybe do the water pump and gasket. No need to replace the engine. They are built pretty well and this should be rebuildable easily. You will see the cause of the problem when the head comes off. Unless the rings gouged the cylinder wall or ruined the piston top (doubtful), this should be basic R and R. You may need the cam holding tool for the head removal. Time consuming but not hard, and uses basic tools. Get access to a Bentley manual first. Oh yeah, what about coolant system?
Bill in Omaha '86 535i
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Please allowo me to add a tidbit here.
The #3 Cylinder's Exhaust Port is a known area where a crack can occur. This crack happens between the valve seat and the adjacent water jacket/galley/passage (chose the term you like best, they are all functional equivelents to me for the purpose of this discussion). (Bill, the OP did mention noticable "white smoke," which is normally steam as opposed to smoke, so there is a very real possibility that there is a crack in the head.)
All I am suggesting is that your only trouble might be a crack in the head and the resulting failure of the gasket in the immediate area of the crack. Whether you need rings or not, I can't tell. But, you have to remove the head as Bill says in order to understand what is happening.
You (the OP) needs to do the stuff that Bill suggests, but while doing it be sure to inspect the head in the area of the exhaust valve seats and the adjacent water galley. I'm not certain if there can be cracks at other locations or not, but the head on my M50 motor definitely was cracked where I talking about.
Having said all of that, I have to wonder if you could have a leak-down result that comes solely from a crack at the exhaust port.
Either way, I'd remove the head. If the rings need replacing, it

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