Unexplained Oil Leak
I am looking for some thoughts about the source of an oil leak on my 86 street/drag hatchback with a 351W. The engine is setup a little loose with ring gaps of .027", .018" and .030" top to bottom, since I race it. Two piece rear mail seal, FelPro one piece oil pan gasket and metal oil rails under the pan bolts. Cam has LSA of 110 degrees. Old school Holley carb and no computer. Rear gears are 4.10s.
Using 30W conventional oil for break in. Oil leak appeared towards the back of the engine, so I thought I might have spun the rear main seal loose. Here's what I found when I got it up on the lift:
Entire bottom of oil pan has a light coating of oil, including the front and back of the pan up to the pan seals. No oil on the sides of the pan, except a little near where the dipstick tube bolts to the side of the pan. All pan bolts are dry, except the last 7/16" bolt from the rear on the passenger side and the rear 1/2" bolt on the driver side which were each holding a drop (neither bolt moved when I tried to re-torque to spec). The bottom of the mechanical fuel pump is lightly coated with oil, but no oil anywhere on the oil filter. Engine block and heads are completely dry. The bottom of the K-member is oily from the center of the engine to the driver side control arm, but dry on the passenger side K-member and control arm. Heavier oil coating on the outside of the C4 inspection plate, the bottom of the engine separator-plate, bottom half of the bellhousing, and transmission pan. Light coating of oil downwind from there. Virtually no oil inside the bellhousing, and no oil on the engine side of the flexplate. PCV valve is full of oil.
Doesn't look like the rear main seal is faulty, since there's virtually no oil inside the bellhousing. Is this just excessive blow-by? Any thoughts as to the source of my leak?
Failure is only the opportunity to begin again more intelligently. H. Ford
1966 A code 4sp Fastback
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1986 351 C4 Hatchback
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