How can I tell if my head gasket is leaking?

As the title says I need to know what few signs start to show a leaking head gasket. The Jeep is a 97 XJ with the 4.0L auto 4x4. I see quite a bit of relatively fresh oil residue on the passenger side of the block and it doesn't appear to be coming from the valve cover. I replaced the valve cover gasket almost 2 years ago. I am also pretty good about not making a mess when I do oil changes so I'm pretty positive its not from that either. I just changed the oil pan gasket and rear main seal. I took a good hard look at the oil filter housing but it doesn't appear to be leaking and I replaced it about 5 years ago. Oil really starts to show up about two inches back from the front of the block and goes all the way back. I replaced the header recently and got a good look at the driver side of the block and it didn't look bad at all almost no oil residue just the very slight seepage that any motor that old with nearly 200,000 miles on it would show.

Thanks in advance for the help.

I would like to hear some input on this as well. I noticed a small amount of a similar leak of some fluid definitely coming from the head gasket. I have no other leaks with 209,000 because I have managed to patch them all with the valve cover leak being the largest. Does having a slight fluid leak in a head gasket cause your engine to run any differently i.e. erratic idle?

Can anyone help out with this?

Ok, the oil return is on that side of the engine and the headgasket tends to "weep" oil in that area.

No biggee, keep it cleaned up and monitor your oil useage/loss.

My 89 is weeping there as well. Got real bad recently, or so I thought. Replaced the oil filter adapter o-ring again and its back to the slow weep.

As a side note, don't bother getting the Dorman 82560http://wiki.rockauto.com/1989 JEEP ...) OHV_Oil Filter Adapter O-Ring_1181708_11896 OFA o-ring kit. The only o-ring that was the correct size was the big one. I had to scrounge to replace the other smaller ones.

Well if thats the case then I am glad I don't have to worry but it does seem like a lot of oil. I am seeing signs of an oil leak from underneath like the little drop of oil that builds up at that small point at the very bottom of the bellhousing. And since all the other seals and gaskets have been recently replaced or check out just fine that is the only one I could come up with. But I have more to worry about right now like a dead alternator and another cracked header. I guess it is just that time where the Jeep is finally starting to show her age.