Having somewhat recently "studied" the B20 pressurized oil path (due to a problem engine that was exchanging oil and water internally), I can give you a fairly detailed description of how oil gets from the block to the head and eventually to the rocker assembly. I'm fairly certain this would apply to all versions of the B18/B20.

The center bearing of the camshaft is pressurized from below, via an oil galley in the block from the oil pump. This center cam bearing shell has a slot cut in the center of it that allows pressurized oil to also flow out of the bearing area to another small oil galley in the block, this one running upwards, parallel to and about 1/2 inch to the left of, the left center head bolt. This galley can be seen when the head is removed. What you will NOT see however, is a matching oil galley in the head. Instead, due to an oval opening that is cut in the head gasket between the galley and the nearby headbolt bore, oil flows from the block galley, across the gap between the galley and the headbolt, and fills the headbolt bore (that portion of it that is not occupied by the headbolt itself) in the block and the head. The block portion of this bore is a dead end, but the matching bore in the head has an oil galley bored at an angle (aftwards and upwards) from the bolt bore towards the #3 rocker assembly tower bolt. It is through this galley that the oil from the head finally enters the rocker shaft assembly. You can actually see a casting "bubble" in the top of the head that allows for this galley, when you have the rocker cover removed. You will also see a relief cut in the head at the #3 rocker tower bolt bore to allow for oil flow, if you have the rocker assembly removed.

So... if you have oil to NONE of the rockers, you have a block and/or head supply galley problem, or a blockage in the #3 tower of the rocker assembly. Obviously, if you have oil to some of the rockers, but not others, it is a problem in the rocker assembly itself.

As for the oil leak from between the head and block on the left side of the engine, this almost has to be a separate issue, most likely a head gasket problem in that particular area.

WRT to oil in the cylinder(s), if you have a "break" in the head gasket in just the right place, I suppose it's possible you could pump a little oil to a cylinder under the right conditions. But I would definitely expect you would also be pumping combustion products the other direction through that break, so you would see highly reduced power on that cylinder due to bad compression.


Gary L.
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1971 142E ITB racer, 1973 1800ES, 2002 S60 T5