As a new guy to this forum, but long time jeeper I hate to start off with another 4.0 oil leak question, but I’m stumped, and I apologize for the lengthy backstory and completely understand the TL/DR aspect of these things.
But I’ve replaced the usual suspects, some twice (oil filters, distributor gaskets, oil pressure sensor, rear main, oil pan, valve cover, etc.). It doesn’t seem to leak or mark its spot on short trips (12 miles to work) below 55mph. Somewhere between 55-60 after a few minutes, it’s almost as if pressure builds up somewhere and forces oil out of a magical spot. Not a lot of oil, but enough to leave a light film on the bottom of the Jeep, burn some off on the exhaust and leave a small couple of drops after it’s parked. The next time it’s driven to work on my below 55mph route and no leak. This is extremely consistent and repeatable. I’ve gotten the leak to happen once in the driveway when idling for an extended time (30+ minutes). With a drop of oil from the lip of the oil pan below the rear main, onto the flex plate and flung onto starter/exhaust. (inspection cover removed for, well inspection in the driveway/was installed during all the road tests). Rechecked all oil pan/valve cover bolts, wiped all the oil off everything, ran the Jeep for what seemed like forever with no leak, thought all was well. Came out the next morning to what I can only explain as being evidence of a small oil explosion, (again not much oil, maybe not even a 1/4 cup) but the oil covered the backside of the oil pan, and pooled inside the bellhousing with a small drip forming on both the drain plug bolt and the bottom of the bell housing. Almost as if there was pressure built up in the oil pan that finally released sometime during the night.
The ccv system appears to operate (vacuum present and functioning check valve thingy) and the inside of the valve cover appears extremely clean.
The Jeep has 135k but nothing is as it should be, with unknown history… the block is a 96 with 93 heads/intake in a 93 yj. It seems to run fine, starts right up, haven't noticed any other signs or issues, radiator fluid is still green and full, I wouldn’t really care except it keeps getting all over the exhaust and I hate that smell.
Any thoughts, ideas, anything? This has me stumped and a little frustrated!! Thanks in advance for any and all help!!
But I’ve replaced the usual suspects, some twice (oil filters, distributor gaskets, oil pressure sensor, rear main, oil pan, valve cover, etc.). It doesn’t seem to leak or mark its spot on short trips (12 miles to work) below 55mph. Somewhere between 55-60 after a few minutes, it’s almost as if pressure builds up somewhere and forces oil out of a magical spot. Not a lot of oil, but enough to leave a light film on the bottom of the Jeep, burn some off on the exhaust and leave a small couple of drops after it’s parked. The next time it’s driven to work on my below 55mph route and no leak. This is extremely consistent and repeatable. I’ve gotten the leak to happen once in the driveway when idling for an extended time (30+ minutes). With a drop of oil from the lip of the oil pan below the rear main, onto the flex plate and flung onto starter/exhaust. (inspection cover removed for, well inspection in the driveway/was installed during all the road tests). Rechecked all oil pan/valve cover bolts, wiped all the oil off everything, ran the Jeep for what seemed like forever with no leak, thought all was well. Came out the next morning to what I can only explain as being evidence of a small oil explosion, (again not much oil, maybe not even a 1/4 cup) but the oil covered the backside of the oil pan, and pooled inside the bellhousing with a small drip forming on both the drain plug bolt and the bottom of the bell housing. Almost as if there was pressure built up in the oil pan that finally released sometime during the night.
The ccv system appears to operate (vacuum present and functioning check valve thingy) and the inside of the valve cover appears extremely clean.
The Jeep has 135k but nothing is as it should be, with unknown history… the block is a 96 with 93 heads/intake in a 93 yj. It seems to run fine, starts right up, haven't noticed any other signs or issues, radiator fluid is still green and full, I wouldn’t really care except it keeps getting all over the exhaust and I hate that smell.
Any thoughts, ideas, anything? This has me stumped and a little frustrated!! Thanks in advance for any and all help!!
