Engine Knock

So lately I have noticed that my engine has a slight knock in it. It happens both hot and cold, and seems to be coming from directly above the oilpan. Thats where you can hear it the best. I thought i needed a quart or so of oil, because my rear main seal does leak, but after checking my oil is full. And CLEAN at that. I use only Mobil1 fully synthetic, and do all P.M. on time. Anybody have any opinions? I also seafomed it about a month ago, and absolutely nothing came out. A little white cloud of smoke and that was it. I'm clueless...

does it knock with increased rpms?
how is the oil pressure.
my 89 has been knocking at idle for about 15 years now.

It might knock at higher rpm's, but I can't tell becuase the engine becomes louder than the knock. So the knock isn't getting any louder. The oil pressure is fine. If I let it idle for like 5-10 straight it will drop, but perks right back up if I rev it. It's a 97 too...

Just out of curiousity, can you get ahold of a stethescope and check around your distributor? I had various hard to trace knocking sounds from my '88 before I put in my rebuilt 4-oh. While pulling the old engine apart, I noticed the distributor's shaft has a lot of up and down play. If I hold the dist in one hand and push up and down on the drive gear, I get a knocking sound that is very much like the sound we heard when the engine was running. I haven't been able to find any specs on how much play is allowable, but it just has me wondering...
Wouldn't it be nice if that's all your problem was?

My '97 had a similair symptom. Replaced the lifters. Still there. Ended up being a cracked piston that eventually broke and put a rod through the side of the block. I've heard that after '96 those silly NVH 'improvements' caused problems like this.

It's hard to tell without hearing it though, but good luck.

If its an AT check your flexplate bolts and flexplate for cracks.

Yea it is an auto, I'm gonna get ahold of a stethoscope and see if I can't get it pinned down to one location.