Drove the model a last weekend for about 80 miles. When I got home I noticed oil leaking out the r side header. Pulled the header off, rr passenger side exhaust port full of oil, so I'm thinking, a broken ring? So I pull the piston, rings/piston appear ok. Then after thinking/talking to a few mechanics, I pull the exhaust/intake valve out of this same cylinder, thinking a damaged guide. Both guides/valves look ok. Back to when I pulled cylinder head off, this piston had excesive amount of oil sitting on bottom of piston in cylinder. Cylinder bore checks out/looks ok. Now what? 1946 Flathead.
Are you sure the bore all the way down is straight? Did you check ring end gap at 3 points down where the rings slide? Say, you move the ring end gap to 6 o'clock looking down, then move the ring gap to say 10 and 2 o'clock for the triangle bore check. Then move the ring down the center of the bore and measure again. Kind of mickey mouse way of measuring. Feeler gauge between the piston skirt and the clean untouched bore area for the piston would tell how loose everything is. Being a flat head, where is the trickle down oil from the rockers? So, I would assume it is a ring sealing problem? Can't be a crankcase pressure problem or the other cylinders would pack up with oil. What about wrist pin rock? Was the engine kind of noisy?
Cylinder does not measure more than .003 out of round. Motor has no piston knock, and carries 30 to 35 pounds of oil pressure at idle. Piston lands all look ok. Thanks, Dan
How does the guide fit in the block? One or two peice guide and did you put o rings on the exhaust along with the intake guides?
Guide fits in block tight/normal. One piece guides. I've been running this motor for a year. I've never ran o rings on exhaust guides, never had a problem.... till now.
Since the intake side sees vacum and the exhaust sees presure, if I was looking for a bad valve guide leaking oil, I would look at the intake valve. Or a vacum leak in the intake manifold gasket between an intake port and the lifter valley could suck in oil. Did it smoke?
No excessive smoke, valves in this cylinder were not covered in oil, normal carbon build up on top of valves. But the piston top was oily, and the combustion chamber on head in this cylinder are clean/oily, with no carbon buildup. Other three piston tops have no sign of having oil on top of pistons/normal carbon on piston tops. The intake gasket had soaked up oil in it toward the rear of motor, more so than the frt. The intake gasket appears to be dry, except toward the rear of gasket. I am running a electric fuel pump., with a welsh plug in oilpump shaft. Thanks, Dan
Can't be a fouled plug/wire(?) and there is you wet cylinder? It could have been firing but the fuel started to build up, wash the cylinders with oil, mixed with the gas, puddled in the piston you are looking at? Short of reassembling, the cylinder calls for a leak down to determine which is causing compression loss... gasket, cracked block, cracked head, porous head, ring integrity?
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