Hello atf,
This oil leak location is vexing me. I have a '96 F-150 I-6. On parking the vechicle I get about 100 drips of engine oil. Last September I changed out the oil pan gasket. Right now I can't localize the location of the oil leak.
Only the left side (looking foward) of the block has oil coating. Nothing is leaking out of the tailpipe. The inside of the exhaust pipe is pristine. And I do not see any oil coating or leaking on the right side of the block. The oil drips down off the saddle shaped cross member that spans between the motor mounts and is ahead of the deep draw portion of the oil pan sump. The pan is rusty, and I could believe a hole in the pan would provide a leak. Furthermore, the gasket is damp with oil and this is the case *after* I changed out the old, cracked oil pan gasket, which I thought was the source of the oil leakage.
I could guess that the oil leak is from the front and rear main seals. But this engine has 90K miles. The oil leak started rather suddenly; I noticed it this past July and it has stayed the same or gotton a bit worse. As I have mentioned, I changed out the oil pan gasket this past September. However, I can't believe my guess that the main crank seal is leaking because I have oil dampness on the entire left side of the block, front to back and up to the elevation of the head gasket but not above the head gasket. The motor mount on the left side shows dampness from the oil. One more thing, a bit over a year ago I changed out the oil plug and o-ring gasket as that was a source of some leakage, and things were fine from that point until this past June-July.
Right now my oil consumption from the leak is about a quart on every third gas fill up. Before this leak started I had about 1/2 quart to add every 3 thousand miles, ie every oil change.
One more thing. The side of the engine block that has complete oil dampness has a long rectangular cover that is attatched to the engine block. What is under this cover? Push-rods? I could guess that this is the problem, but the dampness from the oil is both above, ahead, below, and aft of this narrow-long rectangular cover.
Given how quickly the oil drops off and pools under the engine after parking, 100 drips/15 minutes then it stops dripping, this suggests to me that I have a leak from the pressure side of the oil system. I could guess the oil pressure sender, but the dampness is extensive in area. The oil pan gasket is not on the pressure side of the oil system; or am I wrong? What about a plugged PCV? I don't know where the PCV is located, on top of the valve cover? Again, I don't have any oil dampness from the head gasket on up topside.
Finally, a loose oil filter. No. It is tight. And I change the filter every 3000 miles on the oil change. And the oil dampness is above and in front of the oil filter, but the dampness is on the same side of the engine block as the filter. And the other side of the engine block shows no oil dampness.
Boy, I purchased this 1996 F-150 with 40K miles four plus years ago thinking I was getting something sturdy and a good runner. (Very soon the clutch slave cyl. had to be changed out! Arrgh!) And now this oil leakage problem. But it is not piston blow by. No blue smoke. No sooty exhaust pipe.
Thanks for any suggestions.
Rob Mohr